Cooking Computer

There has been for a long time a need for a device to control precisely cooking of comestibles and deep fat fryers precisely and easily. A number of approaches have been developed in the prior art.

U.S. Pat. No. 3,979,056 to Barnes for a Multi-Product Cooking Computer discloses an electronic circuit having a timer controlled in part by a temperature probe submerged within heated oil or shortening in a deep fat fryer well. The temperature probe controls the rate of oscillation of an oscillator 22. Oscillator 22 drives a counter 24. When counter 24 counts a predetermined number of oscillations of oscillator 22, an output signal is provided indicating that cooking has been completed. In other words, Barnes employs a temperature adjusted oscillator to perform a type of time-temperature cooking integration. Barnes also provides a plurality of product selection switches which connect different resistances in series with a capacitor 68 to control the period of the oscillator. However, should it become necessary to adjust the time for which a particular product selection switch conditions the oscillator internal adjustments of a mechanical or electronic nature would have to be made to the circuit.

Another approach was taken in U.S. Pat. No. 4,197,581 to Watrous et al, for a Control System for and Method of Controlling a Cooking Appliance. Watrous teaches the use of a combination microcomputer controller having associated circuitry for controlling a deep fat fryer. Watrous, preloads timing counters from diode matrices. Watrous, like Barnes, employs a temperature variable frequency oscillator but uses it to actuate microcomputer counters. The variable frequency oscillator of Watrous is controlled by a cooking control probe R801 so that as the probe, which is submerged in heated oil, becomes warmer, the oscillator runs faster. There is no provision in Watrous for altering the preload cooking counter without rewiring a circuit board.

There appears to be no prior art on a precise apparatus and method for controlling a deep fat fryer and having the facility for reprogramming. The reprogramming facility should be usable by persons in authority without the problems associated with tampering of controlled information by unauthorized persons.

A cooking computer is disclosed herein which employs a reprogrammable microprocessor control. The cooking computer is adapted for use with a deep fat fryer wherein more than two food products, possibly of different types, are to be cooked simultaneously in the same shortening.

The controller has a temperature sensing probe which supplies analog temperature information to an analog-to-digital converter. The analog-to-digital converter supplies binary temperature information to a microprocessor. The microprocessor is controlled by a stored program and by recipe constants stored in keyboard alterable permanent memory. Cooking time loaded into alterable memory is modified during a cooking operation to adjust for changes in the rate of cooking due to temperature fluctuations in the oil bath.

The contents of part of the alterable permanent memory may be changed by authorized users having knowledge of an access code of the alterable memory of microprocessor control. Unauthorized users are prevented from making program changes. Up to twelve recipes can be stored in alterable memory. Each recipe includes cooking time and a time-temperature adjustment factor referred to hereinafter as a sensitivity factor. Each of the recipes can have a different cooking time and sensitivity factor.

It is an object of the present invention to provide a reprogrammable cooking computer with a deep fat fryer. It is another object of the present invention to provide a cooking computer for a deep fat fryer which adjusts cooking time as a function of the temperature conditions of a shortening bath.

It is still another object of the instant invention to provide a cooking computer for a deep fat fryer having seven segment displays to display cooking oil temperature, remaining adjusted cooking time and/or hold time for previously cooked products.

Other objects of the present invention will become obvious to one skilled in the art upon a period of the following specification and claims in light of the accompanying drawings.

FIG. 1A is a portion of the schematic diagram of the instant cooking computer showing details of a power supply and basket lift control circuits;

FIG. 1B is a portion of a schematic diagram of a cooking computer showing details of an analog-to-digital converter and a central processing unit;

FIG. 1C is a schematic diagram of a portion of a cooking computer showing details of various memory devices and an input/output port;

FIG. 1D is a schematic diagram of a portion of a cooking computer showing electrical connections to a left hand 7-segment display and details of a display controlled and associated circuitry;

FIG. 1E is a portion of a schematic diagram of a cooking computer showing electrical connection details to a right hand 7-segment display, a light emitting diode display control and a keyboard and keyboard encoder;

FIG. 2A is a sectional view of a deep fat fryer having a frying basket, the position of which is controlled by the cooking computer;

FIG. 2B is a schematic diagram of the fryer heater shown in FIG. 2A and heater controlled thermostat;

FIG. 3 is a flow diagram of the initialization routine stored in the cooking computer ROM;

FIGS. 4 and 4A are flow diagrams of the supervisory section of the program stored in ROM;

FIGS. 5A-D are flow charts of the PROGOP or reprogramming routines stored in ROM;

FIG. 6 is a flow diagram of the EAROM factory burn only routine stored in ROM;

FIG. 7 is a flow diagram of the temperature computation routine stored in ROM;

FIGS. 8A-F are flow diagrams of the cooking cycle control routines stored in ROM;

FIGS. 9A-D are flow diagrams of alarm, hold, analog-to-digital converter, and LED flashing utility routines stored in ROM;

FIG. 10 is a flow diagram of the interrupt routine stored in ROM;

FIG. 11 is a flow diagram of the call subroutine stored in ROM;

FIG. 12 is a flow diagram of the return subroutine stored in ROM;

FIG. 13 is a flow diagram of an input/output actuated for control of the fryer basket lifts stored in ROM;

FIG. 14 is a flow diagram of the hold time comparison subroutine stored in ROM;

FIG. 15 is a flow diagram of a display blinking subroutine stored in ROM;

FIG. 16 is a flow diagram of a command word incrementing routine stored in ROM;

FIG. 17 is a flow diagram of a display buffer subroutine stored in ROM;

FIG. 18 is a flow diagram of a buffer restored subroutine stored in ROM;

FIG. 19 is a flow diagram of a clear buffer subroutine stored in ROM;

FIG. 20 is a flow diagram of a buffer restore subroutine stored in ROM;

FIG. 21 is a flow diagram of a BCD to binary numerical conversion routine stored in ROM;

FIG. 22 is a flow diagram of a binary to BCD in numeric conversion routine stored in ROM;

FIG. 23 is a flow diagram of a routine to erase select storage locations in EAROM and subsequently rewrite new information to the storage locations;

FIG. 24 is a flow diagram of a subroutine which initiates a display controller;

FIG. 25 is a flow diagram of a subroutine which transfers information to a display controller;

FIG. 26 is a flow diagram of a routine which sends information to a display controller which controls a plurality of LED indicators;

FIG. 27 is a flow diagram of a routine which reads select contents of the EAROM;

FIG. 28 is a flow diagram of a subroutine which sends messages to a display controller which controls 7-segment displays;

FIG. 29 is a flow diagram of a subroutine which sends messages to a display controller to control the 7-segment displays;

FIG. 30 is a flow diagram of a subroutine which sends alpha numeric to a display controller to control 7-segment displays;

FIG. 31 is a flow diagram of a subroutine which blinks the 7-segment displays;

FIG. 32 is a flow diagram of a subroutine which processes information received from the keyboard;

FIG. 33A is a flow diagram of a routine which displays time elapsed in a cook cycle or during a fryer recovery routine;

FIG. 33B is a flow diagram of a subroutine which tests for keyboard switch closings to determine which if any cooking recipes have been selected;

FIGS. 34A-B are flow diagrams of an integration subroutine which partially adjusts cooking timers in response to the difference between the shortening temperature and a temperature set point;

FIG. 35 is a flow diagram of a timer diagram routine;

FIG. 36 is a flow diagram of a routine which converts degrees Celsius to degrees Fahrenheit;

FIG. 37 is a flow diagram of a multiple subroutine;

FIG. 38 is a flow diagram of a division subroutine;

FIG. 39 is a flow diagram of a degrees Fahrenheit to degrees Celsius conversion routine, and;

FIGS. 40A-B are flow diagrams of a fryer recovery routine.

A cooking computer 10 for use with a deep fat fryer 12 having an electric heater 12a and a thermostat 12b is generally disclosed herein. Cooking computer 10 has a thermal probe 14 located in a deep fat fryer well 16 for submersion in heated oil to sense the temperature thereof as does thermostat 12b. As will be explained in greater detail hereinafter, the temperature probe 14 is connected to an analog-to-digital converter which supplies digital signals to a microprocessor, indicative of the temperature of the oil in the deep fat fryer. The microprocessor processes the digital temperature signals using a program and data stored in a Read Only Memory and other data stored in an Electrically Alterable Read Only Memory (EAROM). A timing counter has its periodic updating facility conditioned in response to the temperature of the oil to reflect accurately the amount of cooking completion of a particular foodstuff placed in a basket 18 lowered within the well 16. After a predetermined time, as adjusted for temperature variations in the oil, the microprocessor gives a command to a motor control circuit to cause a motor 19 drivingly connected to the basket 18 to raise the basket 18 from the well 16 to terminate cooking of the foodstuff.

The instant cooking computer includes a power supply generally referred to by the numeral 30 and shown in FIG. 1A. Power supply 30 includes a power supply plug 32 which is connected to a transformer 34 at a primary winding 36. Power transformer 34 also has a pair of secondary windings 38 and 40. A first full-wave rectifier bridge 42 is connected across secondary winding 38. A second full wave rectifier bridge 44 is connected across secondary winding 40. A filter capacitor 46 is connected between a lead 48, which is connected to bridge 44, and a ground lead 50, which is connected to a ground terminal 52 of plug 32. A reverse poled diode 54 is connected to bridge 42 at its junction with a lead 56. Lead 56 supplies filtered DC current to a voltage regulator 58, in this instance, an LM337MP regulator configured as a clamp. The regulator 58 has a resistor 60 connected across its adjustment lead 62 and its output lead 64. A filter capacitor 66 is connected between regulator output lead 64 and ground lead 50. Regulator output lead 64 provides a source of electric power to the basket lifts.

A second LM337MP voltage regulator 68 also configured as a clamp is connected to diode 54 and to a capacitor 70. Again, an adjustment lead 72 and an output lead 74 are connected together by a resistor 76. Resistor 76 comprises a portion of a voltage divider which includes a resistor 78 connected to ground lead 50. The output of voltage regulator 68 is fed through lead 74 and is filtered by a capacitor 80 connected between lead 74 and ground lead 50. An audible alarm device, such as a buzzer 82, is connected to the junction of capacitor 80 and lead 74 and is also connected to other portions of the circuit to provide an output indication on certain specified conditions such as cooking completion hold time expiration or data entry. Alarm 82 is connected through a lead 84 to a pair of buffers 86 connected to a pair of NAND gates 87 comprised of a 74C908 integrated circuit. All of the NAND gate input leads 87a are tied together and connected to a lead 88. Furthermore, the outputs of buffers 86 connected to the NAND gates 87 are connected in parallel to buzzer lead 84.

A resistor 90 is connected to bridge 44 and secondary winding 40 of power transformer 34 to receive alternating current at line frequency and feed it to a diode 92 connected thereto. A tap lead 94 is connected to diode 92 and receives essentially have wave rectified voltage therefrom. The half wave rectified voltage is partially filtered by a capacitor 98 connected between lead 94 and ground lead 50. Lead 94 is also connected to an inverter 96 which drives a capacitor 98 and a resistor 100 to provide a triggering edge to a second inverter 102. Inverter 102 is connected to an RCA CDP 1802 microprocessor configured as a central processor unit 104 at its interrupt pin 106, thereby causing interrupt signals to be generated in central processor unit 104 in synchronism with the alternating current line frequency feeding the power supply 30.

Voltage regulator 110, in this case, an MC7805CT has an input terminal 112 connected to capacitor 46, a ground terminal 114 connected to ground lead 50 and an output terminal 116 connected to diode 92. In addition, a capacitor 118 is connected between diode 92 and ground lead 50 and has a regulated power supply or VCC lead 120 connected thereto. VCC lead 120 provides a 5 volt power supply potential to buffers 86, NAND gates 87 and other portions of the circuit. VCC lead 120 is also connected to a VCC terminal 122 of CPU 104 and a VDD terminal 124 of CPU 104. A ground terminal 126 of CPU 124 is connected to ground.

CPU 104 also has a clear terminal 128 which is supplied with signals by a pair of series connected inverters respectively numbered 130 and 132 connected to a resistor 134 and a capacitor 136, which are series connected between ground and a source of intermittent voltage supplied to reset or clear CPU 104. A quartz crystal having a resonant frequency of 2 MHz is connected in parallel with a resistor 140, the parallel combination being connected across a clock pin 142 and an XTAL pin 144 of CPU 104. CPU 104 is an 8 bit microprocessor and has 8 data or data bus pins which are identified herein by the numerals 150 through 157, each of which are connected to a resistor collectively identified by numeral 158 which are all connected to VCC lead 120. Data bus leads 150 through 157 are collectively referred to herein as data bus 160. A wait pin 162 is also connected to one of the pull up resistors 158.

In addition, a pair of Direct Memory Access pins 164 and 166 are connected in parallel to one of a plurality of resistors 168. Resistors 168 are connected to VCC lead 120 to provide voltage pull up to the CPU 104 pins. CPU 104 also has eight memory address pins, respectively identified by numerals 170 through 177, numeral 170 representing the lowest order bit, and numeral 177 representing the highest order bit. Each of pins 170 through 177 are connected through a respective pull up resistor of plurality 168 to VCC lead 120. Address leads 170 through 177 together comprise an 8 bit address bus 180.

CPU 104 also has a memory read pin 182 to which is connected to a memory read line 184. A Q flip-flop pin 185 is connected to buzzer control lead 88. A memory write pin 186 has a memory write line 188 connected thereto. A TPA or timing pulse A pin 190 has a TPA line 192 connected thereto. CPU 104 also has a TPB pin 194 together with a plurality of N lines; an N0 line 196, an N1 line 198, and an N2 prior line 200. TPB line 194, N0 line 196, and N1 line 198 are shown herein for simplicity sake as comprising a timing and control bus 202. N2 pin 200 is connected to an N2 line 204.

CPU 104 also includes a plurality of input flag terminals hereinafter identified in the manufacturer's scheme as terminals EF1 through EF4 having the corresponding identifying numerals 206, 208, 210 and 212. Terminal 212 is connected to ground by a jumper only during manufacturing burn-in and diagnostic routines. Terminal 210 is connected to ground to place controller 10 in its multiproduct mode. When terminals 210 and 212 are not connected to ground they are held at VCC by a pair of resistors 214 and 216 connected to lead 120 at a point 218.

Referring to the lower left portion of FIG. 1B, there is shown a constant current generator 220 which includes an operational amplifier 222 having an inverting terminal 224 connected to a variable resistor 226, a fixed resistor 228 and another fixed resistor 230, which is connected to an output terminal 232. A fixed resistor 240 is connected between a power supply lead and inverting terminal 224. A noninverting terminal 242 is directly connected to output terminal 232. The constant current output supplied by constant current generator 220 is fed through a lead 224 to the RTD thermal probe 14 and back to ground. Lead 244 is also connected to an analog to digital converter 250, in this embodiment, a Model ADC0803LCD. Analog to digital converter 250 is powered from line 120 at a VCC pin 252. A ready pin 254 is connected to flag pin EF1 or pin 206 of CPU 104. A read pin 256 is connected to memory read pin 182 of CPU 104 to provide a processing completion signal to CPU 104. A chip select or CS pin 258 is connected through an inverter 260 to line 204 for receipt of control signals from N2 line 200 of CPU 104. A write pin 262 is connected to lead 188.

A first voltage reference generator 270 comprised of an operational amplifier 272 and voltage divider network 274 is connected to a pin 276, in this instance, the V minus pin of analog to digital converter 250 to provide zero offset to analog to digital converter 250. A second substantially identical voltage reference supply 280 having an operational amplifier 282 and a voltage divider 284 is connected at its output to a pin 286 in this case the reference divide by 2 pin of analog to digital converter 250. A V plus pin 288 is connected to lead 244 for receipt of the voltage signal across the RTD probe 14 which is indicative of the temperature of the fryer shortening. An AG pin 290 is connected to the opposite side of the RTD probe 14 and a CC and CR pin, respectively numbered 292 and 294 are connected together by a resistor 296 which is connected to ground through a capacitor 298. A plurality of data bus pins 297 from analog to digital converter 250 are connected to the data bus 160 of CPU 104 to supply an 8 binary digital signal to CPU 104 representative of the voltage drop across the RTD probe, which is indicative of the temperature of the shortening bath.

Volatile memory for information processing by the CPU 104 is provided by a Random Access Memory or RAM 310. In the instant embodiment RAM 310 is an RCA CDP1823 128 byte random access memory. Other random access memories could also be used by one skilled in the art. RAM 310 is connected to VCC lead 120 at a VCC pin 312 and a chip select or CS pin 314. Furthermore, a plurality of data bus pins respectively numbered 320 through 327 with pin 320 being the lowest order pin and 327 being the highest order pin. Data bus pins 320 through 327 are connected to data bus 160. A memory read pin 330 and a memory write pin 331 are respectively connected to memory read pin 182 and memory write 186 of CPU 104. A plurality of three chip select pins respectively numbered 334, 336 and 338 together with a VSS pin 340 are all connected to ground. A pin 342 commonly known as the A12 pin or address 12 pin on RAM 310 is hereinafter used as a chip select pin and is connected to a lead 344. A plurality of address pins respectively numbered 350 through 356 is connected to address bus 180. RAM 310 is used to store variables frequently changed and used by CPU 104 during computations. RAM 310 is unable to store information when power is not being supplied.

The program to operate CPU 104 is stored in a permanent memory, in this instance, a Texas Instruments TMS2532 Erasable Programmable Read Only Memory or EPROM, hereinafter identified by numeral 360. EPROM 360 is powered by VCC lead 120 at its VCC pin 362 and pin 364, its VDD pin. EPROM 360 is also connected to ground at a pin 366. EPROM 360 also has a plurality of data bus terminals, respectively, 370 through 377, with terminal 370 identifying the lowest order bit and terminal 377 identifying the highest order bit. Data bus pins 370 through 377 are connected to data bus 160 for communication with CPU 104. Furthermore, EPROM 360 receives address signals through a plurality of memory address pins 380 through 391. Pin 380 is the lowest order pin and pin 391 is the highest order pin. Pins 380 through 387 are connected directly to address bus 180. Pins 388 through 391 are respectively connected to a local decoder bus 392. A chip select pin 393 is connected to lead 344.

Since CPU 104 can access over 65,000 bytes of memory which requires memory addressing with a 16 bit number and since CPU 104 only has an 8 bit memory address bus, it is necessary for CPU 104 to supply the address of the information to be accessed from the EPROM 360 in two fetch cycles. Thus, as is well known in the art, it is necessary for a portion of the address bits to be latched with an address decoder 400 a National Semiconductor 74C174 Hex D Flip-Flop is used. Address decoder 400 has a power supply pin 402 connected to line 120. An inverter 404 connects TPA line 192 from CPU 104 with a flip-flop clock terminal 406. A latch request terminal 408 is connected to CPU 104. A plurality of flip-flop memory address pins respectively numbered 410 through 414 is connected to address bus 180 to receive information therefrom. In this instance, memory address pin 410 is the lowest order pin, memory address pin 414 is the highest order pin. A plurality of address output pins, respectively numbered 418 through 422, is connected to local bus 392 to feed the highest order bits of the address output by the CPU in two cycles to EPROM 360.

Certain specific program information such as recipe constants which include sensitivity factors and recipe times in minutes and seconds is stored in an Electrically Alterable Read Only Memory 430, in this embodiment, a Nitron ER 7055 EAROM, having 64 bytes of storage. EAROM 430 has a VCC pin 432 which is connected to receive power from VCC line 120. A CS2 or chip select 2 pin 434 is connected in parallel VCC pin 432 to lead 120. A power supply filter capacitor 436 is connected in parallel with pins 432 and 434 and to ground. A VGG pin 438 is connected to a lead 440 and to a grounded filtered capacitor 442. Lead 440 is connected to lead 74 of the power supply 30. EAROM 430 has a ground terminal 442 connected to ground and has a plurality of data bus terminals 450 through 457 connected to a local bus data 458. Similarly, a plurality of EAROM address terminals 460 through 467 are connected to another portion of local bus 458 which in this instance provides address information to address pins 460 through 467. In addition, control information is provided by a local bus 458 to a chip select pin 470 and a clock pin 472 of EAROM 430.

A programmable two port input/output device hereinafter referred to as PIO 500 and which is in this embodiment an RCA CDP 1851, is connected to receive information from and transfer information to data bus 160, control bus 202 and local data bus 458, as will be explained in more detail hereinafter. PIO 500 is connected to VDD lead 120 at a VCC pin 502 and a chip select 504. A filter capacitor 506 is connected to pins 502 and 504 and to ground. CPU data bus 160 is connected to a plurality of PIO bus pins 510 through 517 for the transfer of information to and from the CPU 104. Control bus 202 is connected to a memory read pin 520, a TPA pin 521, a TPB pin 522 and NO pin 523 and N1 pin 524 and a clear pin 525. PIO 500 has a pair of input/output ports, the first one, identified as Port A, is comprised of a plurality of Port A IO pins 530 through 537. Port A includes a Port A strobe pin 538 and a Port A ready pin 539. In a similar fashion, the second Port is identified as Port B and includes a plurality of Port B I/O pins 540 through 547. Port B also includes a Port B strobe pin 548 and a Port B ready pin 549. All communication with displays, LEDs, the keyboard and the basket lifts is through PIO 500. In addition, all communication with EAROM 430 is through PIO 500. The only external information which is supplied to controller 10 without being processed by PIO 500 are the temperature signal provided by the RTD probe and the interrupt timing signals.

An input/output latch 560 is connected to bus 458 and more specifically, to pins 540, 541 and the Port B strobe pin 548 at a plurality of pins 562, 564 and 566. I/O latch 560 is powered from lead 120 at a power supply pin or VCC pin 568. A pin 570 is connected to control bus 202 and to the clear pin on the CPU. A first latch output pin 572 is connected to a lead 574 which supplies latched signals to basket lift controllers. A second output pin 576 is connected to a lead 578 to supply other output signals to basket lift controllers. In the present embodiment I/O latch 560 is a National Semiconductor 74C175 Quad D Flip-Flop. Lead 576 connects to parallel input terminals of a NAND gate 580 which is in turn connected to a buffer 582 and supplies an electrical signal through a resistor 584 to an optical coupler 586 having a light emitting diode 588. Light emitting diode 588 controls a silicon controlled rectifier 590 which is connected to power supply lead 64 and a left basket relay lead 592. A diode 594 is connected to ground for surge current protection.

In a similar fashion, a NAND gate 600 is connected as an inverter to lead 578 and supplies its output to a buffer 602 which drives an optical coupler 604 through a resistor 606. Current flowing through resistor 606 is supplied to a light emitting diode 608 of optical coupler 604 which controls a silicon controlled rectifier 610. Silicon controlled rectifier 610 is also connected to lead 64 and to a right lift basket relay lead 612. A protective diode 614 is connected between 612 and ground. Lead 612 is connected to a basket lift control motor for a right hand basket of the deep fat fryer. Lead 592 is connected to the left hand basket of a deep fat fryer. Signals on lead 592 and 612 control the raising and lowering of the respective baskets in the heated oil of the deep fat fryer. Thus, CPU 104 controls the position of the baskets in a deep fat fryer through PIO 500, latch 560 and NAND gates 580 and 600.

Referring to FIG. 1D, PIO bus 458 is connected to a display controller 650 for driving a digital display 652. Display controller 650 is, in this embodiment, an Intersil ICM 7218AIJI display controller. Display controller 650 is energized from VDD line 120 at a VCC pin 654. A write pin 656 is connected to a clock lead 658 which is driven from Port A strobe terminal 538 of PIO 500. A local Port A bus 660 which is connected to bus 458 and carries the signals from Port A terminals 530 through 537 is connected to display controller 650 at a plurality of pins which are numbered 670 through 677 and correspond to pins 7, 5, 6, 10, 14, 13, 11 and 12 in the manufacturer's numbering scheme. In addition, display controller 650 has a plurality of output lines 680a, 680b, 680c, 680d, 680e, 680f, 680g and 681 which correspond respectively to pins 426, 24, 2, 25, 1, 3 and 27 in the Intersil numbering scheme.

Pins 680a through g are connected to a plurality of LED seven segment numeric displays 690, 691, 692, 693, 694, 695, 696 and 697 in conventional fashion as is well known to those skilled in the art. The individual displays are sequentially enabled by signals from a plurality of pins 700, 701, 702, 703, 704, 705, 706 and 707 which correspond to pins 15, 16, 23, 20, 17, 22, 21 and 18 in the Intersil numbering scheme. A mode pin 710 is connected to a lead 712 for receipt of signals from a latch 714 to which it is connected. Latch 714 is a 74C175 Quad D Flip-Flop powered from lead 120 by supplies voltage received at pins 716 and 718 which respectively correspond to pins 16 and 8 in the National Semiconductor numbering scheme. Latch 714 also has a plurality of input pins specifically numbered 720, 722, 724 and 726 which are respectively connected to pin 547, 546, 545 and 543 of PIO 500 through local bus 458. A pin 728 is connected to Port B ready pin 549. Pins 720, 722, 724, 726 and 728 correspond to pins 4, 5, 13, 12 and 9 in the National Semiconductor numbering scheme. Lead 712 is connected to a pin 730 of latch 714. Latch 714 also has output pins 732 and 734. Pins 730, 732 and 734 correspond to pins 15, 2 and 11 in the National Semiconductor numbering scheme.

Referring now to FIG. 1E, a keyboard 750 is shown therein in schematic fashion. Keyboard 750 includes 16 membrane switches respectively numbered 751, 752, 753, 754, 755, 756, 757, 758, 759, 760, 761, 762, 763, 764, 765 and 766 which correspond respectively to key numbers 0 through F as encoded in hexadecimal notation. Keys 751 through 756 are the left basket product keys. Keys 757 through 762 are the right basket product keys. Keys 763 through 766 are control keys. All keys are located on a face portion of the control 10 immediately beneath displays 690 through 697. The keys are connected to a keyboard encoder 770, in this instance, a National Semiconductor 75C922 16-key encoder, through a plurality of pins 771 through 778, inclusive, which correspond respectively to terminals X1, X2, X3, X4, Y1, Y2, Y3 and Y4 in the National Semiconductor numbering scheme. Keyboard 770 is powered from lead 120 at a pin 780 which corresponds to pin 16 in the National Semiconductor numbering system. Four pins, 781 through 784, are connected to Port A bus 660 to provide a 4-digit number to the four lowest order Port A pins. The four digit binary number being indicative of switch closure of one of the key switches 751 through 766. The keyboard encoder 770 has an output enable pin 786 connected to lead 734 from latch 714. A data available pin 788 is connected to a lead 790 which is connected to pin 206 of CPU 104. The EF4 flag pin, an oscillator pin 792, a ground pin 794 and a key bounce in 796 are connected through capacitors to ground.

A second display controller 800, in this instance, also an ICM 7218 AIJI, is powered at its VCC pin 802 by current from line 120 for which filtering is provided by capacitor 804, a mode pin 806 is connected to lead 733 to receive signals from the pin 732 output terminal of latch 714. A plurality of input pins 810 through 817 corresponding respectively to pins 7, 5, 6, 10, 14, 13, 11 and 12 in the Intersil numbering scheme are connected to Port A bus 660 for communication herewith. A plurality of output terminals respectively 820 through 823 are connected in parallel as are a plurality of output pins 824 through 827. Pins 820 through 827 correspond to pins 15, 16, 20, 17, 22, 21 and 18 in the Intersil numbering scheme. Pins 820 through 823 are connected to a common lead 828. Pins 824 through 827 are connected to a common lead 829. A plurality of individual output pins respectively numbered 830a through g correspond to pins 27, 3, 1, 25, 2, 24 and 26 in the Intersil numbering scheme.

A first plurality of light emitting diodes 850, 851, 852, 853, 854, 855, 856 and 857 are connected in parallel to lead 828 and respectively to pins 830a through 830h and correspond to and are located adjacent to keys 757 through 764. A second plurality of light emitting diodes 860, 861, 862, 863, 864, 865, 866 and 867 are connected in parallel to lead 829 and respectively to pins 830a through 830h to be energized thereby. Light emitting diodes 860 through 867 correspond to keys 751 through 756, 765 and 766 and are located immediately adjacent thereto.

When controller 10 is initially switched on the program stored in EPROM 360 begins in CPU 104. Details of the program are set forth in a program listing and associated comments which is attached hereto and is made a part of this disclosure. In addition, FIGS. 3 through 40 comprise flow charts which describe the specific functions of the program which forms a part of this disclosure.

Execution of the program begins with initialization of all of CPU 104's scratchpad registers, followed by zeroing all of the RAM 310 locations for later receipt of data. The display comprising seven segment LEDs 690 through 697 is also blanked. A test is performed to determine whether the cooking computer is configured for a single product or for multiple products. As disclosed herein the cooking computer is a multiple product computer. The temperature to which the fryer is to be set, as previously stored in EAROM 430, is fetched to RAM 310 along with information establishing a plus or minus 15.degree. Fahrenheit temperature window about the program temperature. In addition, information from the EAROM specifying a fryer high limit temperaure of 390.degree. F. is also loaded into RAM 310 where it is available for processing.

An additional feature of the initialization routine sets controller commands to insure that the basket lifts are raised. The initialization routine also operates an interrupt driven timer which is first interrupted by signals supplied through lead 94 to start a timer running and is then interrupted by the next positive going zero crossing potential supplied through lead 94 to stop the timer from operating in order to determine the frequency of the line voltage of the power supply.

A supervisory routine is next entered which tests a command word to determine which of several states the controller should be operating in. One of the states is a cooking state wherein at least one of the baskets is immersed in the oil and cooking counters are running. Another state is a fryer recovery state wherein a timer is initiated when the oil temperature sensed by the RTD probe reaches 275.degree. and the timer is shut off when the RTD probe temperature reaches 325.degree. thereby giving the user an indication of the amount of time required for the fryer to return to an operating temperature. The fryer recovery state also provides a running indication of elasped time in a display. A temperature display state may be entered to display the temperature of the RTD probe. A program state allows certain of the variables stored in EAROM, such as sensitivity and cooking time to be changed.

When the computer is first switched on, the user receives a visual signal caused by LED 857 blinking. Should the user then press membrane switch 757 the controller 10 enters the programming mode wherein the product temperature may be reset as stored in the EAROM by punching the new temperature in through the keyboard 750. Once the temperature has been set individual program recipes may be altered by pressing the appropriate membrane switch which first interrogates the user as to whether a sensitivity factor was identified as the CFAC variable should be changed. The sensitivity factor in effect determines the magnitude of time temperature correction to be performed by the integration routine stored at addresses OB96 through OC53. In addition, the minutes and seconds information stored in EAROM for the particular membrane switch depressed may also be changed by entering new information through the keyboard.

In order to obtain access to the memory in EAROM for purposes of re-programming, it is necessary that the operator enter a four-digit code when the microcomputer interrogates him with the cooking code on the display. The routine which controls the interrogation and code checking is located at addresses 0173 through 0181 and is identified as PROG81. This program also interrogates the user as to whether temperature information is to be displayed and set in terms of the Celsius scale or the Fahrenheit scale. The user selects the Fahrenheit scale or Celsius scale by depressing membrane switch 750 to respond to the Celsius prompt in the left hand display or by depressing switch 757 to respond to the Fahrenheit prompt in the right hand display. PROG84 located at address 026E through 02A4 performs the actual storage of the programmed temperature data. It should be apparent that since two baskets are being used in a single oil bath only one temperature set point is required for the instant controller. Once processing of PROG84 is complete, PROG85 prompts the user with the signals SELP in the display which requires the user to press a product key (one of keys 750 through 752). Once the product recipe has been selected, PROG86, located at address 02BC and 02EE, takes over and interrogates the user and receives new user information regarding the sensitivity factor for the program as well as the cooking time in minutes and seconds.

In addition, the user can program the amount of hold time to be displayed by the microcomputer. Hold time is defined as the amount of time following cooking of the last batch of product for which a vendor wishes to retain the product before disposing of it. Certain well-known fast-food chains, for instance, require that french fried potatoes, which had been cooked more than seven minutes before selling to a user, be disposed of. The hold time may be programmed through reentries similar to the cooking time when PROG88 at addresses 0351 through 0374 is entered.

The programming mode may be exited by pressing command key 755 following entry of a particular recipe data.

A cooking operator routine which is stored between addresses 0451 and 061E tests keyboard inputs to determine if a cook key 750 has been depressed. In the event that a cook key has been depressed a cook cycle is initiated wherein the appropriate basket lift is lowered and a cooking timer begins running within the microcomputer. Since the temperature sensed by RTD probe 14 varies during the course of foodstuff cooking, it is necessary to adjust the cook time for temperature variations. An integration routine beginning at address OB96 and ending at address OC53 compares the actual temperature as received from the analog to digital converter 250 to the set point temperature and computes the difference as a delta factor. The delta factor is divided by two and multiplied by the integer stored as the sensitivity constant for the particular recipe. This number is then added to a number previously stored in an accumulator register. The program tests the contents of the accumulator and when the total stored in the accumulator is greater than the set point temperature stored in EAROM 430 the seconds timer of the cooking out program is adjusted by one count. If the fryer temperature is higher than the set point temperature the cooking time is decremented by one. The temperature dependent decrement takes place independently of the periodic one second decrementing of the cooking counter which occurs on a regular basis. Thus, the cooking timer is adjusted to compensate for temperature differences above or below the set point fryer temperature.

All timers running in the program are updated on a regular basis in synchronism with interrupts generated by positive zero voltage crossings of the line frequency.

Following is an assembly language listing program of 63 pages in length stored in Read Only Memory 360: ##SPC1## ##SPC2## ##SPC3## ##SPC4## ##SPC5## ##SPC6##

Therefore, it is apparent that the cooking computer 10 provides a higher accurate temperature compensated timer which can be re-programmed in the field with ease by users quite rapidly. Although a specific embodiment of the cooking computer 10 has been disclosed in detail above, it may be appropriate that various modifications and changes may be made in the instant invention without departing from the spirit and scope. It is to be explicitly understood that the instant invention is limited solely by the appended claims.