Planter population monitor
BACKGROUND OF THE INVENTION 
     The present invention relates generally to novel monitoring apparatus, and more specifically to a novel monitoring apparatus for monitoring a plurality of functions of a machine. While the features of this invention are useful with different machines, the disclosure will be facilitated by addressing the specific problem of monitoring the planting of seeds by a multi-row seed planting machine. 
     As is well known, a farmer engaged in mechanized planting of seeds generally utilizes a planting machine pulled behind a tractor. One form of planting machine commonly used includes a plurality of seed planting units carried on a single frame for simultaneously planting a plurality of rows of seeds. With such multi-row planting equipment, it is often difficult for the farmer to monitor operation of all the planting units with any degree of accuracy. In this regard, it is also important to ascertain that all planting units are operating to achieve a desired seed population per acre, at least within reasonable limits. In order to determine seed population planted by each planting unit, as well as by the planting machine as a whole, it is necessary to determine the number of seeds planted by each planting unit of the planting machine, the ground speed of the planting machine, the number of rows being planted, and the row width or spacing between rows. 
     A number of prior monitoring systems have been proposed for monitoring seed population planted by a multi-row planting machine. Representative of these prior art systems are those described in the following U.S. Pat. Nos.: Fathauer et al 3,855,953; Steffen 3,912,121; Knepler 3,927,400; Fatheuer 3,928,751; and Steffen 4,085,862. While these prior art systems have proven particularly useful for the purposes and functions described therein, none is capable of simultaneously monitoring and storing information from all rows of a multi-row planting machine, while at the same time monitoring the distance travelled. It will be appreciated that such capability is particularly advantageous, in that the farmer can immediately ascertain the population currently being planted in any row, or, by the machine as a whole. In contrast, in the prior art system, to ascertain seed population for a given row, it was necessary for the farmer to first select the row (i.e., planting unit), and then wait for the apparatus to accumulate a seed count over a given distance for that row. Consequently, for a large planter, e.g. one having 12 or 16 planting units, the farmer would have to wait a corresponding number of distance intervals to ascertain the seed population being planted in all rows and only thereafter could he determine the population being planted by the machine as a whole. Collaterally, should one or more rows be malfunctioning or failing to achieve the desired seed population, the farmer might not become aware of the situation until a considerable amount of ground had been covered by the planting machine. 
     The advent of advanced electronic components, including such elements as microprocessor components and including electronic memory elements, has made possible rapid gathering, storage and retrieval of relatively large quantities of data. The present invention advantageously provides a programmed, special purpose microprocessor for simultaneously monitoring a plurality of functions of a machine such as a multi-row seed planter, and storing data corresponding thereto. 
     As will be more further detailed herein below, the use of a programmed, special purpose microprocessor also makes possible the storage of a plurality of data samples or data points taken of the various functions to be monitored at predetermined intervals. Such a plurality of data samples or data points are manipulated by the programmed microprocessor, to provide heretofore unavailable information to the operator. For example, the average of a plurality of data points or samples of a function being monitored may be displayed upon command. In a multi-row seed planting machine, such average values are obtained for a particular row, or for all of the rows being planted by the machine. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Accordingly, it is a general object of the present invention to provide a new and improved monitoring apparatus for simultaneously monitoring a plurality of functions of a machine. 
     A more specific object of the invention is to provide a new and improved monitoring apparatus especially adapted to monitor the seed population planted by a multi-row seed planting machine. 
     Another object is to provide a new and improved monitoring apparatus of the type described adapted to simultaneously receive and store seed population planted in all rows of a multi-row seed planting machine, and to provide therefrom useful output data in the form of observable displays or other indications, to assure the operator of proper functioning of the seed planting machine. 
     Briefly, in accordance with the foregoing, a monitoring apparatus in accordance with one aspect of the invention includes a special purpose computer operating in accordance with a predetermined program for simultaneously and continuously monitoring the seed population planted by all rows of a multi-row seed planting machine, and for producing observable indications of seed planting to an operator of said multi-row seed planting machine. 
     In accordance with another aspect of the invention, a monitoring apparatus is provided for simultaneously monitoring a plurality of functions of a machine. The monitoring apparatus includes a microprocessor operating in accordance with a predetermined program for simultaneously continuously receiving and storing data from a plurality of sensor means which detect the machine functions being monitored. User accessible control means including observable indicator or display means are coupled with the microprocessor, the microprocessor operating in accordance with the program and in response to commands from the control means to produce observable indications of the machine functions being monitored. 
     In another aspect of the invention, a monitoring apparatus is provided for use with a multi-row seed planting machine, which includes electronic circuit means for simultaneously continuously detecting the planting of seeds in all rows of the multi-row planting machine and storing a plurality of samples of this data, taken at predetermined intervals. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, advantages and features of the present invention are described in more detail in the following description of the illustrated embodiment, taken together with the drawings, wherein: 
     FIG. 1 is a plan view of a seed planting machine, partially in diagrammatic form, wherein the apparatus of this invention is advantageously incorporated; 
     FIG. 2 is a block diagram of the monitoring apparatus of the present invention in conjunction with a plurality of sensors associated with the seed planting machine of FIG. 1; 
     FIG. 3 is a front elevation of a control and display panel advantageously mountable for viewing by an operator of the seed planting machine of FIG. 1; 
     FIG. 4 is a diagram, in tabular form, illustrating one mode of operation of the monitoring apparatus, in accordance with advantageous features of the present invention; 
     FIG. 5 is a schematic circuit diagram illustrating in additional detail, a portion of the monitoring apparatus of FIG. 2; 
     FIGS. 6A and 6B, taken together, form a schematic circuit diagram of a further portion of the monitoring apparatus of FIG. 2; and 
     FIGS. 7A and 7B, taken together, form a schematic circuit diagram illustrating a portion of the circuit of FIG. 5 in additional detail. 
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT 
     Referring to the drawings, the present invention will be described in conjunction with a multi-row planting machine. However, no limitation is intended, the invention being useful in other applications as well. 
     FIG. 1 illustrates a mobile, multi-row seed planting machine 10, transported by a tractor 12, over a field to be planted. The planting machine or planter 10 may be of various known constructions and need not be described in detail. It suffices to state that the planter 10 includes a plurality of seed planting units or chutes 14, through which seeds are delivered to be planted in the ground. In the particular embodiment illustrated, the seed planting units or chutes 14 are eight in number. It will be understood, however, that the monitoring apparatus of the invention may be readily adapted for association with planters having any desired number of planting units or chutes 14. The planting units 14 may be of various known constructions and need not be described in detail. 
     The seed planting units 14 each have associated therewith a seed sensor 16, which is adapted to provide an output signal in response to the passage of a seed through the associated seed planting unit or chute 14. The sensor 16 forms no part of the present invention and will not be described in further detail. Suitable sensors for this purpose are described, for example, in U.S. Pat. Nos. 3,723,989 and 3,928,751 to Fathauer, and 3,974,377 to Steffen, all owned by the present assignee. The planter 10 also incorporates a distance or ground speed sensor 18, conveniently mounted adjacent to a wheel such as a press wheel 20 of the seed planter 10. This distance or ground speed sensor 18 also forms no part of the present invention and may comprise a tachometer or the like of known construction. The sensor 18 produces a given number of output pulses in response to a given number of rotations of, or to a given distance travelled by the wheel 20. Suitable cables, designated generally 22, electrically join the seed sensors 16 and ground speed or distance sensor 18 with a housing 23 mounted on the planter 10, which contains components of the monitoring apparatus of the invention. These components in the housing 23 in turn feed a control and display console 24 mounted on the tractor, via a cable 25. The console 24 is conveniently mounted on the tractor for viewing by the operator. This console 24 contains the remainder of the monitoring apparatus of the invention, and may be provided with suitable electrical operating power via a suitable cable or cables 26 from the tractor battery 28. 
     Reference is now invited to FIG. 2, wherein the major components forming the invention are illustrated in block diagrammatic form. The seed sensors 16 and the ground speed or distance sensor 18 feed the monitoring components in the housing 23, which in turn feed the monitoring components of the console 24. 
     The components in the housing 23 and console 24 include a microprocessor, which will be described in detail herein below. Briefly, the microprocessor includes an input interface or input/output section 30 which receives the inputs from the sensors 16 and 18, and is joined by a bi-directional data transfer line or cable 32 with a main microprocessor section 34. Miscellaneous additional functions of the seed planting machine 10 may also be monitored at additional inputs or sensors 36, joined by bi-directional data transfer line 38 with the main microprocessor section 34. The main microprocessor section 34 is bi-directionally joined by lines 40 and 42, which form the cable 25 of FIG. 1, with elements of the console 24. These elements include display interfacing components 44 and an operator accessible display and control panel 46, bi-directionally joined by a line 47. 
     With reference to FIG. 3, the console 24 is illustrated in front elevation, revealing the display and control panel 46, as viewed by the operator of the tractor 12. Referring to the control and display panel 46 of FIG. 3, together with the block diagram of FIG. 2 the operation of the invention will now be described. The structural details of the components comprising the functional blocks of FIG. 2 will be described in detail later. 
     The main microprocessor 34 operates in accordance with a predetermined, stored program to continuously monitor and store the signals from all of the seed sensors 16 and from the distance or ground speed sensor 18. These signals are simultaneously received at the input interface 30 and fed to the main microprocessor 34, which calculates seed populations for each row therefrom. Advantageously, the main microprocessor is capable of storing in memory components, which will be described later, a plurality of these seed population calculations or seed counts from each sensor 16. These seed population calculations or seed counts are made, in accordance with the program, over successive, predetermined increments of distance travelled by the seed planter, as determined by the microprocessor from the input signals of the ground speed or distance sensor 18. The microprocessor is further responsive to operator input from the control panel 46, as will be described in detail later, for storing data or information corresponding to the configuration of the particular seed planting machine 10 with which the monitoring apparatus is being utilized. Thus, the monitoring apparatus of the invention may be customized for use with a particular seed planting machine such as the seed planter 10 of FIG. 1. For example, the microprocessor 34 is programmed to receive information or data corresponding to the number of rows, that is, the number of seed planting units or chutes 14 of the planter 10, and to the spacing therebetween. This data is also used by the microprocessor in calculating the seed population planted. 
     The display and control panel 46 includes a left-hand display portion or window 48, a right-hand display portion or window 50 and a center display portion or window 52. Function select (FUNC SEL) push-button control switches 54, 56 and 58 are associated with the left-hand display window 48, the right-hand display window 50 and the center display window 52, respectively. Additional controls include an on/off (ON/OFF) push-button switch 60, a digit advance (DIGIT ADV) push-button switch 62, a digit select (DIGIT SEL) push-button switch 64 and an operate/set up (OPR/SET UP) switch 66. The center display window 52 includes a plurality of words or symbols, designated generally 68, which are selectively back-lighted by operation of the function select control switch 58, to indicate selection of a particular function to be performed by the microprocessor. A four-digit display 70, in the middle display window 52, comprises four conventional 7-segment digit liquid crystal display characters, and is utilized to provide a display of the value of the currently selected planting machine function. The left-hand display window 48 includes a plurality of words or symbols, designated generally 72, selectively back-lighted by the operation of the function select control 54 to indicate selection of additional functions performed by the microprocessor. A two-digit display 74, also in the left-hand window 48, comprises a pair of conventional 7-segment liquid-crystal display characters, which together with a back-lighted word &#34;ROW&#34; adjacent thereto, are selectively lighted to indicate the row number for which a reading is being given in the display characters 70 of the center display window 52. The right-hand display window 50 also includes a plurality of back-lighted words or symbols, designated generally 76, similarly selectable by function select control 56 to indicate further microprocessor functions and to give malfunction indications to the operator. A similar two-digit display 78 together with a back-lighted word &#34;ROW&#34;, is provided in the right-hand display window 50 to indicate the row number of the multi-row planter to which any energized display symbol 76 applies. 
     Initially, the microcomputer system is turned on by depressing the ON/OFF switch 60. In accordance with a feature of the invention, the microprocessor may be customized or programmed for use with a given planter 10 by depressing the OPR/SET UP control 66 to back-light a symbol &#34;SET-UP&#34; in the right-hand display window 50. Next, the FUNC SEL control 54 is depressed to back-light a symbol &#34;LO FAIL SET&#34;, in the left-hand display window 48. In this mode of operation, the microprocessor will accept operator input for the lowest acceptable seed population or &#34;low limit&#34; of seed population to be planted. The display digits 70 of the middle window will be energized at this point, all reading zero. The operator may then actuate the DIGIT SEL control 64 to energize the digits 70 individually, depressing the DIGIT ADV control 62 to advance each energized digit to the desired number. Repeating this process with the DIGIT SEL and DIGIT ADV controls 64 and 62, the operator may then set in a number in the digital display 70 indicating the low limit seed population to be planted, in thousands. For example, a setting of 22.5 indicates a low limit seed population of 22,500 seeds per acre. Depressing the FUNC SEL control 54 will then light the symbol &#34;HI FAIL SET&#34; in the left-hand display window 48, whereupon the high limit of acceptable seed population may be set in, in the same fashion as for the low limit. For example, setting in a figure of 27.5 would indicate a high limit of acceptable population of 27,500 seeds per acre. 
     The microprocessor is provided with two memory compartments or registers for accumulating a count of area planted by the seed planting machine. The operator may utilize these two area counters or registers in any convenient fashion. For example, one register might be utilized to keep a count of the field area planted by the machine on a single day, or in a single field to be planted, while the other is utilized to accumulate a count of the total area planted by the seed planter over a planting season. In this regard, the function select push-button 54 may be depressed to selectively back-light symbols &#34;FIELD AREA&#34; and &#34;TOTAL AREA&#34; in the display window 48, thereby selecting the respective registers. The cumulative count in the selected register will then be displayed in the middle display digits 70, and the operator may use the digit select and digit advance controls 64 and 62 to set these counts to any desired starting point, in acres. 
     In accordance with another feature of the invention, the microprocessor is also programmed to selectively activate or de-activate any of the seed sensors 16. For example, when planting end rows of a field, the farmer may wish to use less than all of the seed planting units 14 of the planter 10. Alternatively, should a particular planting unit 14 or its sensor 16 be non-operational, the farmer would wish to exclude that particular unit or seed sensor from the monitor. Accordingly, the FUNC SEL 54 control may be depressed to light a symbol &#34;ROW ON/OFF&#34; in the right-hand display window 48. In this mode, a &#34;ROW ON/OFF&#34; symbol will also appear in the right-hand display window 50, and the symbol &#34;ROW&#34; and digits 74 of left-hand display 48 will be energized. By depressing the DIGIT ADV control 62, the row indicating digits 74 may be advanced sequentially from one up to the total number of rows or seed planting units 14 on the planter 10. As each row number is displayed, the operator may then depress the FUNC SEL control 56 to light either the &#34;ON&#34; or &#34;OFF&#34; symbol in the display window 50 thereby indicating that that particular row is either on or off for purposes of monitoring by the microprocessor. 
     The microprocessor may now be customized or programmed for the planter configuration by depressing the FUNC SEL push-button 54 to light a &#34;NO. ROWS&#34; symbol in the display window 48. This will also energize the &#34;ROW&#34; symbol and digits 74. The DIGIT ADV control 62 is then depressed to advance the digits 74 until the number of rows or seed planting units 14 of the planter 10 is indicated. The next depression of the FUNC SEL control 54 lights a &#34;ROW SPACE&#34; symbol in the left-hand display window 48 and energizes the digits 70 of the center display 52. The operator now utilizes the DIGIT SEL and DIGIT ADV controls 64 and 62, in similar fashion to that described above for setting the low and high limits, to set the display digits 70 to read, in inches, the spacing between rows as planted by the seed planting units 14, which number is set into the microprocessor. 
     In accordance with another feature of the invention, the microprocessor may be customized or programmed for giving an indication of the weight of seeds planted by the planter 10. This information is calculated from the seed count, and therefore the number of seeds per unit weight must be programmed into the monitor. This is done by again depressing the FUNC SEL control 54 whereupon a symbol &#34;SEED/WT&#34; is lighted in the display window 48, and the digits 70 of the display window 52 are energized. The operator then may utilize the digit select and digit advance controls 64 and 62 to set in the number of seeds per unit of weight. For example, if soybean seeds are being planted, the number of soybean seeds per one/tenth pound is set in. 
     In accordance with yet another feature of the invention, the microprocessor is programmed or customized in accordance with the particular type of distance or ground speed sensor 18 being utilized with the planting machine 14. This is done by further depression of the FUNC SEL control 54, which lights a symbol &#34;DIST CAL&#34; in the display window 48 and also symbols &#34;SET&#34; and &#34;CALIBRATE&#34; in window 52. Two methods are available for setting a suitable number in the digits 70. In the first method, the operator may determine by reference to a manual or the like provided with the distance sensing device, to ascertain how many pulses are produced by the sensor 18 per given distance of travel. From this information the operator must calculate the number of pulses per 200 feet of travel, and set this number by use of the DIGIT SEL, and DIGIT ADV push-buttons 64 and 62 in the same manner as for the previously described settings. In the second method, the operator measures off a 200 foot course and drives the planting machine 10 over this measured course. At the starting point of the measured 200 feet, the FUNC SEL control 58 is depressed, whereupon the CALIBRATE symbol will be energized and the display characters 70 will be reset to zero and begin accumulating the pulse count from the sensor 18. At the end of the measured 200 foot course, the operator again depresses the FUNC SEL control 58, which then energizes the SET indication and holds the number of pulses accumulated at that point on the display characters 70. This completes the customizing programming of the microprocessor for the particular seed planting apparatus 10 with which the monitor of the invention is being utilized. 
     Depression of the OPR/SET-UP control 66 will now display the symbol OPERATE in the display window 50, whereby the microprocessor is ready to begin monitoring of the planting operation. Depressing the FUNC SEL control 58 will cause display of the functions being monitored, as indicated by the lighting of appropriate ones of the symbols 68 in the center display window 52. In the illustrated embodiment, these available functions are designated as follows: SEEDS/AREA, wherein the display digits 70 indicate the number of seeds per unit area or seed population being planted, in thousands; DIST/SEED an SEEDS/DIST, wherein the display digits 70 indicate the seed spacing being planted in terms of inches per seed or its inverse, the number of seeds planted per foot; SPEED wherein the display digits 70 indicate the speed of the seed planting machine in miles per hour; AREA, wherein the digits 70 display the cumulative or total area planted, in acres; WT/AREA, wherein the display digits 70 indicate the weight of seeds planted per unit area, in pounds per acre. 
     Three additional functions are available in conjunction with the distance per seed, seed per distance, seeds per area and weight per area functions. These functions are selected by operation of the FUNC SEL control 54, to light the appropriate symbols in the display window 48. These functions are as follows: SCAN, wherein the collected and stored data for the seed planting units 14 are scanned, in a predetermined sequence, for display of the calculated figure (distance per seed, seeds per distance, seeds per area or weight per area, as selected) for each row in sequence; ROW SELECT, wherein the operator selects a particular row for display of the selected function, for as long as desired, by operation of the DIGIT ADV push-button 62 to indicate the number of the desired row for display in the row indicating digits 74 of the window 48; and AVG. ALL ROWS, wherein the selected function (distance per seed, seeds per distance, seeds per area or weight per area) has its value displayed for the cumulative average of all rows of the planting machine 10 as calculated by the microprocessor. In conjunction with the choice of the area function in the middle display window 52, the previously mentioned FIELD AREA or TOTAL AREA register contents may be displayed as selected by the FUNC SEL control 54. 
     The microprocessor is also programmed in accordance with a further feature of the invention to provide a number of failure or warning indications in the left-hand display window 50. These failure or warning signals will be displayed whenever the corresponding condition is detected in the seed planter 10, without regard for the function which has been selected for display in the center display window 52. Specifically, for every one/two hundredth of an acre travelled, any row or rows failing to fall within the present high and low limits will be displayed by row number in the digits 78 of the window 50, together with an appropriate symbol &#34;HI&#34; or &#34;LOW&#34;, to indicate whether the detected population is above or below the preset limits. If more than one row fails to fall within the preset limits, the number of each such row will be shown for a predetermined time, consecutively followed by each other such row. At the same time, a symbol &#34;WARNING&#34; will also be energized in the display window 50. If any row or rows fall below a predetermined rate, which in the illustrated embodiment is two seeds per second, that row number will be displayed in the digits 78, together with a symbol &#34;FAILED&#34; in the display window 50. An audible alarm will also be sounded for this condition. In the same fashion as for the high and low limit warnings, if more than one row has failed in this latter fashion, the display will sequence through to show each failed row by number in the digits 78. Similarly, should the distance or ground sensor 18 fail to provide input pulses, a symbol &#34;DIST INPUT FAILED&#34;, will be energized in the display window 50. 
     In accordance with an important feature of the invention, the microprocessor 34 is programmed to provide an averaging or smoothing function for the population data calculated for each row of the seed planting machine 10. This operation is illustrated in tabular form in FIG. 4. In accordance with the program, the microprocessor operates to &#34;update&#34; or calculate a new seed population figure for all rows, for each 1/200 of an acre travelled by the planting machine 10, as determined from the distance or ground speed sensor 18 input. Referring to the horizontal lines of boxes of FIG. 4, in the illustrated embodiment, the memory or storage capacity of the microprocessor 34 includes storage space for four such successive population readings or calculations. In the table, the column headed &#34;NO. 1/200 ACRES&#34; gives the sequential number designation of the successive reading; the column headed &#34;NEXT 1/200 ACRE CALC&#34;, gives an exemplary population calculation for the acreage increment indicated in the first column. The four storage positions or registers are shown in the columns headed &#34;BEFORE TRANSFER&#34; with their contents before the &#34;NEXT 1/200 ACRE&#34; calculation is entered, and in the columns headed &#34;AFTER TRANSFER&#34; after the &#34;NEXT 1/200 ACRE&#34; calculation has been entered. Finally, the column headed &#34;DISPLAY&#34; shows the value which the microprocessor displays in the digits 70 on the display panel 46. In the illustrated embodiment, the first horizontal line of FIG. 4 shows the first population calculation being taken, at initial start-up of the planter 10. The table of FIG. 4 illustrates the process for a single planting row or planting unit 14, it being recognized that the process is the same for each of the other planting units 14 of the planting machine 10. 
     Referring now to the first horizontal row of FIG. 4, in the first 1/200 of an acre the microprocessor has calculated a population figure of 25.0. In the illustrated embodiment, the population figures are calculated and displayed in thousands, whereby 25.0 corresponds to a population of 25,000 seeds per acre. Accordingly, the &#34;BEFORE TRANSFER&#34; column in the first horizontal row shows all zeros (0) in the storage positions, or registers (&#34;REG. 1,&#34; &#34;REG. 2,&#34; etc.). Referring to the &#34;AFTER TRANSFER&#34; column, the microprocessor has entered the value 25.0 in the first storage position or register (&#34;REG. 1&#34;), and, in accordance with the program, the population figure displayed is 25.0, corresponding to the first calculated population measurement. For purposes of illustration, it will be assumed that in this example the high and low limits preset into the microprocessor, as described above, are 22.5 and 27.5 respectively. These figures correspond to 22,500 and 27,500 seeds per acre population. 
     Referring to the second horizontal row, the microprocessor has calculated the population planted in the second 1/200 of an acre as 18.2 (18,200 seeds per acre). As indicated by the arrows, each number currently in the storage positions or registers is shifted over to the next storage position or register to the right, whereby the registers now contain, as shown in the &#34;AFTER TRANSFER&#34; column, 18.2, 25.0, 0 and 0, reading from left to right. In this case, the display digits 70 will show a population reading of 18.2, the microprocessor being programmed to display any calculation made which is outside of the preset high and low limits. It will be remembered that the right hand display window 50 will also be activated at this time to show the number of this row, and to display symbols indicating that the row is below the preset limit. 
     Referring now to the third horizontal row of FIG. 4, the third 1/200 of an acre calculation is 24.6. In similar fashion, as indicated by the arrows in the &#34;BEFORE TRANSFER&#34; column, the numbers in the storage positions or registers are all shifted one position to the right, whereby the zero in the right hand column is discarded, resulting, as shown in the &#34;AFTER TRANSFER&#34; column, in stored figures of 24.6, 18.2, 25.0 and 0. In accordance with its stored program, the microprocessor will now display, in the digits 70, the average of all readings thus far taken which are within the high and low preset limits, resulting in an average reading of 24.8, as indicated in the &#34;DISPLAY&#34; column. 
     Referring now to the fourth horizontal row, headed by the numeral 4 in the &#34;NO. 1/200 ACRES&#34; column, the next 1/200 of an Acre calculation is 25.4, and is entered into the storage positions or registers in similar fashion. Accordingly, the &#34;AFTER TRANSFER&#34; column now shows that all four of the storage positions, or registers, are filled, and the &#34;DISPLAY&#34; column shows the average figure 25.0, which is displayed on the digital characters 70 of the central display window 52. It will be remembered that this figure 25.0 is the average of all of the figures in the storage register which are within the high and low preset limits. Consequently, the figure 18.2, which is below the preset low limit (22.5) is disregarded for purposes of this average calculation. 
     Referring now to the next horizontal column, headed by the numeral 5, in the &#34;NO. 1/200 ACRES&#34; column, the next 1/200 of an acre calculation is 28.4. This figure is entered into the storage positions or registers, and the other figures move forward as previously described. It will be noted that the first taken calculation of 25.0 is now discarded from the last or right-hand most storage position, since the four storage positions, or registers, were filled on the previous reading. Since the population figure just calculated, 28.4, is above the preset high limit (27.5) this figure will now be displayed in the digits 70 of the central display window 52, together with the row number and symbol indicating a row exceeding the preset high limit, in the right-hand display window 50. 
     Referring finally to the last horizontal row, preceded by the numeral 6 in the &#34;NO. 1/200 ACRES&#34; column, the next 1/200 of an acre population calculation is 24.7. This figure is transferred to the first storage register, the other storage figures moving to the right by one position, and the oldest or right-most figure 18.2 being discarded, in the same fashion as described above. Accordingly, the &#34;AFTER TRANSFER COLUMN&#34; shows the contents of the four registers or storage positions as being 24.7, 28.4, 25.4 and 24.6. Accordingly, the average 24.9 is displayed in the digit 70. It will be remembered that this figure 24.9 is the average of the three figures currently stored which are within the preset high and low limits. From the foregoing it will be appreciated that the population displayed will be the average of those figures in the storage positions or registers which are within the high and low preset limits. However, in the case where a new 1/200 of an acre population figure is calculated which is outside of the preset high and low limits, that figure will be displayed for so long as it remains in the first storage position or register. 
     It will be appreciated that the calculation, storage and averaging process carried out with reference to FIG. 4 is simultaneously carried out for all of the planting units 14 of the multi-row seed planting machine 10. Accordingly, the display figures for all rows are available upon command from the operator control panel 46, selecting a particular row to be displayed, or calling for the microprocessor 34 to automatically scan through the rows, as described above. 
     Referring now to FIGS. 5 through 7, the structural details of the functional blocks of FIG. 2 will now be illustrated and described. 
     Referring first to FIG. 5, the input interface circuitry 30 is shown in additional detail, together with the main microprocessor 34, which is again illustrated in block form. The lines 22 from the seed sensors 16 terminate in a plurality of terminals 100, each of which is provided with a pull-up resistor 102 to a positive voltage supply and a series resistor 104 feeding the input of a buffer 106. In the illustrated embodiment there are 16 such inputs 100 for accommodating planting machines of up to 16 row capacity. To facilitate clarity of illustration only the first and last circuit points 100 and associated components 102, 104 and 106 are illustrated, it being understood that one such set of components is joined with each sensor 16, via its associated line 22. Each of the buffers 106 feeds an input of a flip-flop integrated circuit 108, one such flip-flop integrated circuit 108 being provided for each seed sensor 16. The outputs of the buffers 106 also feed the respective inputs of an analog multiplexer/demultiplexer integrated circuit 110. In the illustrated embodiment the buffers 106 comprise integrated circuits of the type generally designated CD4050, the flip-flops 108 comprise integrated circuits of the type generally designated 74L74, and the analog multiplexer/demultiplexer 110 comprises an integrated circuit of the type generally designated CD4067. The Q outputs of the flip-flops 108 feed respective inputs of a circuit block designated generally 112, the first eight flip-flops 108 feeding the inputs of a port designated 114, and the last eight feeding the inputs of a port designated 116. Circuit Block 112 will be illustrated and described in detail hereinbelow. The Q outputs of the flip-flops 108 are tied back to their D terminals by respective lines 118. 
     The distance or ground speed sensor 18 feeds an input terminal 120, illustrated immediately below the circuit block 112. This input 120 feeds a circuit substantially identical to that associated with the seed sensor inputs 100, and comprising a pullup resistor 122, a series resistor 124 feeding a buffer 126 whose output drives a flip-flop 128. The Q output of the flip-flop 128 feeds one input terminal of a port 130 in the circuit block 112. A pair of similar input circuits emanating from circuit points 132 and 134 are provided with pullup resistors 133 to a positive voltage supply and series resistors 135 feeding buffers 136, whose outputs feed additional inputs of the port 130. These auxiliary inputs may be utilized to accommodate sensors for other functions associated with the seed planter 10. 
     The analog multiplexer/demultiplexer 110 is controlled by four control lines designated generally 138, which are driven from four terminals of a port 128, in the circuit block 34. The output terminal 142 of analog multiplexer/demultiplexer 110 feeds a buffer 144 which in turn feeds one terminal of a further port 146 in the microprocessor 34. A final port 148 in the microprocessor 34 has eight terminals, which are joined by data transfer lines designated generally 150 to eight terminals making up the port 140 of the circuit block 112. The first four of these eight data lines are those feeding the control lines 138 of the analog multiplexer/demultiplexer 110. The eight data lines 150 comprise bi-directional data lines, which both feed data to and receive data from eight terminals designated generally 152, at the lower right hand portion of FIG. 5. Each of the terminals 152 is fed from one of a plurality of series connected resistors 154, each of which in turn is fed from the output of one of a plurality of buffers 156. Each of the buffers 156 is provided with a pullup resistor 158 at its output to a positive voltage supply. Similarly, each of the terminals 152 feeds one of a plurality of resistors designated generally 160, each resistor 160 in turn feeding one of a plurality of buffers designated generally 162. The input of each buffer 162 is provided with a suitable capacitor 164 to ground. The buffers 162 each feed a one of a further plurality of buffers, designated generally 166, the buffers 166 feeding the port 148. 
     In the illustrated embodiment, the buffers 156 comprise components of integrated circuit packages of the type generally designated 7416, the buffers 162 are components of integrated circuit packages designated generally CD4050, and the buffers 166 comprise Tri-State buffers and are components integrated circuit packages of the type generally designated 74LS125. A common control line 170 feeds the control inputs of all of these latter buffers 166. 
     Referring again to the microprocessor 34, it will be remembered that the port 146 has eight input/output terminals. A first of these terminals is fed from a strobe output line 172 of the circuit block 112, via a circuit comprising a resistor 174 in series with a buffer 175. A diode 176 is connected in parallel with the resistor 174, its cathode being joined with the line 172 and it is anode with the input of the buffer 175, which input is also joined with a capacitor 178 running to ground. A second input/output terminal of the port 146 is joined by a line 180 to a control terminal of the circuit block 112. The last four input/output terminals of the port 146 feed four data inputs, designated generally 182, of a four-bit latch/four-to-sixteen line decoder 184, which in the illustrated embodiment comprises integrated circuit of the type generally designated CD4514. Four outputs of the integrated circuit 184 terminate, respectively, at four substantially identical voltage supply circuits. Only one such voltage supply circuit need be described in detail. The positive twelve volts obtained from the tractor battery, as will be detailed later, is fed to an input terminal 186, which feeds a positive five volt regulator 188, of the type generally designated 7805. The output of the circuit with regulator 188 provides a regulated positive eight volt supply at an output terminal 190. This output terminal 190 is also provided with a suitable smoothing capacitor 191 to ground. The output terminal 190 is also joined via a resistor 192 to the non-inverting input of an operational amplifier (op amp) 194, which in the illustrated embodiment is of the type generally designated 324. The inverting input of the amp 194 is joined with its output, which in turn is joined with a control terminal of the voltage regulator integrated circuit 188. The non-inverting terminal of the op amp 194 is also joined by a series resistor 196 to ground, and is fed from an output of a bilateral switch integrated circuit 198. An input terminal of the bilateral switch 198 is the point in the circuit fed from one of the above-mentioned output lines of the integrated circuit 184. The four regulated positive voltage supply output terminals 190 are fed to the cathodes of four diodes 200, as indicated by the repeated reference numeral 190, immediately below the integrated circuit 184. The anodes of these diodes 200 are joined together and feed the non-inverting input of an operational amplifier (op amp) 202, whose inverting input is fed by a series resistor 204 to a further positive voltage supply. A series resistor 206 also feeds the same positive voltage supply to the common anode terminals of the diodes 200. A resistor 208 joins the inverting input of the op amp 202 to the ground. In the illustrated embodiment, the op amp 202 is of the type generally designated 324. The output of the op amp 202 feeds a buffer 210, whose output feeds a line 212 which is connected to the third of the eight input/output terminals of the port 146 in the microprocessor 34. 
     Two of the remaining output lines of the integrated circuit 184 feed a buffer 214 and an inverter 216, respectively. The buffer 214 is provided with a pullup resistor to a positive voltage supply at its output and feeds an inhibit terminal 218 via a series resistor. The inverter 216 feeds a buffer 220 which has a similar pullup resistor to a positive voltage supply at its output and feeds a strobe terminal 222 via a series resistor. The remaining outputs of the integrated circuit 184 feed three inverters 224, 226, and 228. The inverter 224 feeds the control line 170 to the buffers 166. The inverters 226 and 228 feed a pair of terminals which are connected to the &#34;clear&#34; and &#34;preset&#34; terminals of the flip-flops 108. 
     Referring now to FIGS. 6A and 6B, the display interface circuitry is illustrated. The terminals 152 of FIG. 5 are joined in the same order illustrated, top-to-bottom as indicated generally by reference numeral 152 in FIG. 6A. For clarity, only the first two and the last two of these terminals 152 and their associated components are illustrated, it being understood that the remaining terminals and associated components are substantially identical. The inhibit and strobe terminals 218 and 222 of FIG. 5 join the like-numbered terminals of FIG. 6A. Each of the terminals 152, 218 and 222 feeds one of a plurality of inverter buffers, designated generally 250, via one of a plurality of series connected resistors designated generally 252. Each of the resistors 252 has a capacitor at either side thereof running to ground. Additionally, each of the terminals 152 feeds the anode of one of a plurality of diodes, designated generally 254, whose cathodes each feed one terminal of one of a plurality of push-button switches, designated generally 256. The opposite sides or terminals of the push button switches 256 are joined in common with a line 258. It will be noted that the seventh one of the eight terminals 152, designated 152-7 is an exception to the above, in that it is not provided with a diode 254 and push-button switch 256. The first three of the push-button switches 256 comprises the push-button control switches 54, 58, and 56 respectively, of the control panel 46 of FIG. 3. The next three of the push-button switches 256 (not illustrated in FIG. 6A) comprise the digit advance, digit select and operate/setup push-button controls 62, 64 and 66 respectively, of the control panel 46 of FIG. 3. The last push-button switch 256, designated in FIG. 6A as 256 L comprises a rear panel control switch on the console 24 actuation of which causes the microprocessor 34, in accordance with the program, to convert all measurements taken from English to Metric system or vice versa. 
     The first four of the inverters 250 feed four inputs of a four-bit latch/four line-to-sixteen line decoder integrated circuit 260, which in the illustrated embodiment comprises the integrated circuit of the type generally designated 4514. Inhibit and strobe inputs of the integrated circuit 260 are fed from the last two of the inverters 250, which, it will be remembered, receive the inhibit and strobe inputs 218 and 222. The first eight of the inverters 250, which receive the terminals 152 from FIG. 5, also feed respective control lines designated generally 262. Twelve of the sixteen outputs of the integrated circuit 260 are utilized and are designated generally 264. Two of the remaining outputs of the integrated circuit 260 feed lines 266 and 268. The tractor battery positive 12 volt terminal is connected at a circuit point 270 which feeds a fuse 272. A suitable diode 274 has its cathode connected to the opposite side of the fuse 272 and its anode to ground. This opposite side of the fuse 272 so feeds the movable contactor of a relay 276, which relay is energized to feed two positive twelve volt output terminals 278 and 279, in response to actuation of the power on/off switch 60. The positive twelve volt terminal 278 feeds the terminals 186 of the voltage regulators 188 of FIG. 5. A &#34;power up&#34; logic system, designated generally 280, is provided in conjunction with the positive battery input terminal 270 and the power on/off switch 60. Remaining inputs to this logic circuit include the lines 266 and 268 from the integrated circuit 260, the line 258 from the switches 256, and a line 282 from the terminal 152-7. This circuit is illustrated in detail in FIG. 6A, and as it does not contribute to understanding of the invention, will not be described in detail herein. 
     Referring now to FIG. 6B, the lines designated generally 262 and 264 are the same as the like-numbered lines of FIG. 6A. These lines are connected with a plurality of liquid crystal display drivers, designated generally 316 and 318. The display drivers 316 comprise integrated circuit liquid-crystal display drivers of the type generally designated CD4056, and each drives one of the seven-segment digital display characters of the display panel 46 of FIG. 3. Specifically, the display drivers designated 320 and 322 drive the digits designated 74 in FIG. 3, the drivers 324, 326, 328, and 330 drive the digits designated 70 in FIG. 3, and the drivers 332 and 334 drive the digits designated generally 78 in FIG. 3. Accordingly, in the illustrated embodiment, the digital display characters 70, 74 and 78 all comprise seven-segment liquid crystal display components. The remaining drivers 318 comprise liquid-crystal display driver integrated circuits of the type generally designated CD4054, and are utilized to drive liquid crystal lighting panels for selectively back-lighting the function or mode indicating symbols described with reference to the display panel 46 of FIG. 3. Specifically, the display drivers 336 and 338 drive liquid crystal back-lighting units for the symbols in the left hand window 48, and for the symbols for operate and set-up modes in the left-hand window 50 of FIG. 3. With respect to the operate and set-up symbols, the last (right-hand) output terminal of the driver 338 drives the operate symbol back-light directly, and drives the set-up symbol via a circuit comprising a transistor 340 whose base terminal is joined to terminal 338 via a series resistor 342. The collector electrode of transistor 340 drives the set-up liquid crystal back-light. Transistor 340 is also provided with a collector resistor 344 to a positive voltage supply VDD and its emitter is connected to a suitable biasing voltage VEE. Further in this regard, the display drivers 344 and 346 selectively energize the liquid crystal back-lights for the symbols located in the display window 52 of the display panel 46 in FIG. 3. In similar fashion, the display drivers 348 and 350 selectively energize the liquid crystal back-lights for the symbols located in the display window 50. Further similar display drivers 352 and 354 selectively energize the remaining ones of the liquid crystal back-lights for the symbols in the display window 48. The remaining display drivers 318 are for energizing additional liquid crystal back-lights for remaining ones of the symbols in the three display windows 48,50 and 52, and extra drivers 318 provide a capacity for driving additional such liquid crystal backlights, for purposes of adding additional symbols and/or functions to the monitoring apparatus of the invention, if desired. 
     The circuit point 281, also labeled VDD in FIG. 6A, together with the circuit point labeled VEE of FIG. 6B provide suitable operating potentials for the display driver components designated generally 316 and 318 A circuit designated generally 360 provides a suitable potential at the circuit point VEE and suitable &#34;display frequency&#34; input signals (BP and BPDIS) at circuit points designated 362 and 364, for the display driver circuits 316 and 318 and for the seven-segment digital display elements. These signals and their derivation are known in the art for such display and driver components and need not be further described herein. The terminal 362 of the circuit 360 also provides one input to a two-input exclusive NOR gate 366, whose other input is received from one terminal of the display driver circuit 348, via a diode 368 and is held at suitable potential by a resistor 370. The exclusive NOR gate 366 feeds the base electrode of a transistor 372 via a series connected resistor 374, the base electrode also being provided with a suitable capacitor 376 to ground. The emitter electrode of transistor 372 is tied to ground, and the collector electrode thereof is connected via a variable resistor 378 to one terminal of an audible alarm 380, whose opposite terminal is connected with a suitable positive voltage supply. Accordingly, transistor 372 acts as a switch, in response to a suitable logic signal from the display driver 348, for energizing the audible alarm 380. The variable resistor 378 acts as a volume control. This audible alarm 380 is sounded in response to detection of a row failure, as described above, in addition to the energizing of the row failure symbol in the display window 50 of FIG. 3. 
     Referring now to FIGS. 7A and 7B, the structural details of the circuit block 112 and microprocessor 34 of FIG. 5 are shown. In the illustrated embodiment, the microprocessor 34 and the circuit block 112 of FIG. 5 are realized in a microprocessor system of the type generally designated F8 and manufactured by the Fairchild Corporation. The components utilized will be described briefly herein with reference to FIGS. 7A and 7B. Reference is also directed to the publications entitled &#34;F8 Users Guide&#34;, and &#34;Guide to Programming&#34;, Publications Nos. 67,095,665 and 67,095,664, copyright Fairchild Camera and Instrument Corporation 1976, both published by the Fairchild Micro Systems Division, 1725 Technology Drive, San Jose, California, 95110. These publications are hereby incorporated by reference. 
     Referring now specifically to FIG. 7A, the terminals of the ports designated 114 and 148, and the terminals of the ports designated 116 and 146, in FIG. 5, form input/output ports of a central processing unit (CPU) 400. In the illustrated embodiment, the CPU 400 comprises a central processing unit of the type generally designated 3850 and manufactured by the Fairchild Corporation, as described in the above-referenced publications. In similar fashion, the terminals of the ports designated 130 and 140 in FIG. 5 are connected as shown to form input/output ports of a peripheral input/output unit (PI/O) 402. In the illustrated embodiment, this PI/O 402 is of the type generally designated MK3871 and manufactured by the Mostek Co. Publications describing this component 402 are also generally available to the public. A static memory interface (SMI) 404 comprises a static memory interface integrated circuit component of the type generally designated 3853, manufactured by the Fairchild Corporation, and also described in the above-referenced Fairchild Publications. 
     Briefly, the microprocessor system of FIG. 7A includes eight bi-directional data transfer or data bus lines, designated generally 406, which are interconnected between the components 400, 402 and 404 as illustrated, for the bidirectional transfer of data therebetween. A group of five control lines, designated in the literature as ROMC lines are designated generally by reference numeral 408, and are interconnected between components 400, 402 and 404 as illustrated. Remaining control lines of the microprocessor components 400, 402, and 404 are designated in accordance with the terms utilized therefor in the above-referenced Publications. It will be understood that like-designated terminals are interconnected as illustrated among the three microprocessor components 400, 402 and 404. 
     The SMI 404 is also provided with a plurality of output address lines, designated generally 410. These address lines 410 are joined via suitable logic to a plurality of electronic memory devices, 412, 414, 416, 418, 420 and 422, for addressing the contents thereof in accordance with commands from the central processing unit 400. These memory devices 412, 414, 416, 418, 420 and 422 also comprise a part of the microprocessor system of the invention. The memory devices 412 and 414 comprise programmable read-only memories (PROM&#39;s) of the type generally designated 2708 or 2716, and manufactured by Intel. These memories are utilized for storing the microprocessor program. The remaining memory components 416, 418, 420 and 422 comprise random access memories (RAM) of the type generally designated 5101 and manufactured by Intel. 
     The bi-directional data bus lines 406 are interconnected with the memory component data lines to facilitate bi-directional transfer of data between the memories and the microprocessor components 400, 402 and 404. This transfer of data accomplishes the execution of the program, in the case of the memories 412 and 414, and the receiving and storage data from the sensors, the performing of required calculations, and the providing of data to the display, in accordance with the operation of the invention as described above. Suitable positive and negative voltage supplied are provided for the microprocessor and memory components. Suitable logic components are interconnected with the address lines 410 and the memories to facilitate the described transfer of data. Specifically, a &#34;CPU READ&#34; output of the SMI 404 feeds one input of a three-input NAND gate 424 whose output feeds a &#34;CS/WE&#34; control input of the PROM 414. The uppermost one of the address lines 410 feeds both inputs of a two input NAND gate 426 whose output feeds a second input of the NAND gate 424 and a first input of another three-input NAND gate 428, whose output feeds a &#34;CS/WE&#34; control input of the PROM 412. A three-input NAND gate 430 has its three inputs tied together at the third input of the NAND gate 424 and feeds a third input of the NAND gate 428. The &#34;CPU READ&#34; output of the SMI 404 also feeds the remaining input of the three-input NAND gate 428. The NAND gates 424, 428 and 430 comprise the components of a triple three-input NAND gate integrated circuit package of the type generally designated 74LS10. The output of the NAND gate 426 also feeds one input of a BCD-to-decimal decoder integrated circuit 432, which has two of its remaining inputs fed from the fourth and fifth address lines 410 of the SMI 404. The first two outputs of the decoder 432 are fed to a &#34;CE1&#34; input of the RAM 416, and to &#34;CE1&#34; inputs of the RAM&#39;s 420 and 422, respectively. The &#34;CPU READ&#34; line of the SMI 404 also feeds both inputs of a two input NAND gate 434 whose output feeds &#34;OD&#34; inputs of all four RAM&#39;s 416, 418, 420 and 422. 
     Referring now to the power supplies for the circuits of FIG. 7A and 7B, illustrated in FIG. 7B, it will be seen that two positive voltage supplies, and one negative voltage supply and ground are interconnected with suitable capacitors designated generally 436, and feed three power supply lines which provide all of the power supply inputs of the components of FIG. 7A and 7B, in a fashion known to those skilled in the art. Additionally, the twelve volt positive tractor battery is joined with a circuit point 438, which feeds positive voltage terminals of the RAM&#39;s 416, 418, 420 and 422 via suitable current limiting resistors. A second, regulated DC voltage supply at a circuit point 440, feeds the same power supply inputs via a resistor 442 and a diode 444, and, via a diode 446, also feeds both inputs of a two-input NAND gate 448. The NAND gate 448 also has a suitable resistor 450 to ground from its inputs, which inputs are also joined with a suitable positive supply voltage from the supplies 435. The NAND gate 448 feeds both inputs of a two-input NAND gate 452 whose output feeds the &#34;CE 2  &#34;  inputs of the four RAM&#39;s 416, 418, 420 and 422. 
     In the case where the PROM&#39;s 412 and 414 are of the type generally designated 2708, circuit points in FIG. 7A adjacent the NAND gates 424, 428 and 430, are jumpered as follows: 512 to 514, 515 to 516. Similarly, when the PROM&#39;s 412 and 414 are chosen as integrated circuits of the type designated 2708 the circuit points 520 and 522 adjacent the power supply inputs 435 in FIG. 7 B are jumpered. When the PROM&#39;s 412 and 414 comprise integrated circuits of the type designated 2716, the foregoing points are jumpered or joined as follows: 512 to 513, 514 to 516, 520 to 521. 
     Referring again to FIG. 7 A the external timer components for the CPU 400 include a resistor 454, a pair of capacitors 456 and 458 and a crystal element 460. Three modes of external timing are available, as known in the art, by different interconnections of circuit points as follows: In the &#34;crystal mode&#34;, circuit points 518 and 519 are jumpered and capacitors 456 and 458 and crystal element 460 are connected as illustrated; in the &#34;external mode&#34; circuit points 518 and 519 are jumpered and the resistor 454, capacitors 456 and 458 and crystal element 460 are eliminated; in the &#34;RC&#34; mode, circuit points 517 and 518 are jumpered, resistor 454 and capacitor 456 are connected as shown, while capacitor 458 and crystal element 460 are eliminated. The &#34;external interrupt&#34; (EXT INT) control lines of the SMI 404 and PI/O 402 may be alternatively enabled, with different circuit point interconnections established as follows. With neither external interrupt line enabled the following circuit points are jumpered or interconnected: 501 to 502 and 506 to 507. With the external interrupt line of the PI/O 402 only enabled, the following circuit points are interconnected or jumpered: 501 to 502 and 506 to 508. With the external interrupt control line of the SMI 404 only enabled, the following circuit points are interconnected or jumpered: 501 to 503 and 506 to 507. With the external interrupts of the SMI 404 and the PI/O 402 both enabled, the connections are as follows: 501 to 504 and 506 to 508. 
     For purpose of fully describing a specific embodiment of the invention, the following pages include an exemplary program for the microprocessor of this invention. This program is reproduced as a source statement including Mnemonic, Operand and comments as appropriate. ##SPC1## ##SPC2## ##SPC3## ##SPC4## ##SPC5## ##SPC6## ##SPC7## ##SPC8## 
     While a specific embodiment of the present invention has been illustrated and described herein, the invention is not limited thereto. On the contrary, the invention includes such changes, alternatives and modifications as may become apparent to those skilled in the art, insofar as such changes, alternatives and modifications fall within the spirit and scope of the appended claims.