DE2754974C2 - - Google Patents

Description

The invention relates to an electronic device according to the preamble of the claim.

Such a device is from US-Z: Hewlett-Packart Journal, Hewlett-Packart Company, 1975, pages 2 to 23 of the "Installation and Service Manual, Model 2640A, Interactive Display Terminal "known from May 1975. This known electric Device contains electronic assemblies before delivery of the device to the end users. Ge Usually a separate test setup is used for this purpose own control unit nacheinan nacheinan to the modules the test signals applied, which make it possible the Funktionsfä ability of the assemblies to check. Also other electrical Appliances such as microwave ovens, washing machines, CB radios, remote Visual aids, vehicle ignition control devices and the like the delivery to the customer are tested, including at These devices are used for their own test setups via the directed special control signals into the devices under test which are usually supplied by a test computer become.  

From DE-OS 26 35 463 a test method for measuring units be who issued with electronic display devices are equipped. This ensures that the displayed Measured value not by an error in the display device is distorted, the display elements become a computerge controlled test cycle subjected to the currents and voltages on the display elements by means of a current comparator or a voltage comparator are measured. If normal value deviating values occur, the display device recognized as faulty. This test method is specially designed for limits checking of elements of a display device, which are too clearly defined in the functional state Current and voltage conditions lead.

The invention is based on the object, a device of a gangs specified type, in which the individual construction groups can be tested automatically without a External control from the outside and own external measuring devices and gauges are needed.

This object is achieved according to the invention with the in the license plate of the claim specified characteristics. At Anwen The feature of the invention automatically becomes a property Test carried out as soon as the existing in the device microprocessor a particular signal, namely a trigger signal, on a its inputs when the device is switched on. This self-test allows both the maintenance personnel as well as a user of the device, at any time its functioning efficiency very quickly and without any effort.

An embodiment of the invention will now be described with reference to the Drawing explained by way of example. Show it:

Fig. 1 is a perspective view of a microwave oven, which is controlled by a microprocessor and which is adapted for performing the self-test,

Fig. 2 is an enlarged view of the control panel of the microwave oven of FIG. 1,

Fig. 3 is a block diagram of the electronic circuit of the microwave oven of Fig. 1 and

Fig. 4 is a block diagram of the microprocessor of the scarf tion of Fig. 3rd

In Fig. 1, a device 1 in the form of a microwave oven is shown, which is controlled by a microprocessor, and in which the self-test can be applied according to the invention. The device 1 includes a housing having a door which allows access to the cooking chamber in the usual way. An operating and display panel 3 , 4 , 5 contains a serving as an input device keypad 3 , the capacitive Be can serve buttons, although switches with mechansichen contacts can be used. As a display unit 4 , a field of indicator lights is provided, which may contain, for example, LEDs 9 , which teach the operator, which process or cycle takes place in the microwave oven 1 . A four-digit further display unit 5 shows the remaining time in a cooking cycle, the time of day or any other numerical information useful to the operator. By means of an on / off switch 6 , the supply energy can be switched on or off. In the cooking chamber, a temperature probe 7 can be used, which is inserted into a mounted in the side wall container.

An enlarged view of the control and display panel 3 , 4 , 5 is shown in Fig. 2. The keypad 3 consists of a glass front plate on which 21 rectangular conductive zones 8 are mounted. When touched by the operator, the capacitance of an area changes, which can be detected by an input circuit. The testing of such a keypad 3 and the associated impaired detector circuit is difficult because the parts are unreachable and would be influenced by test probes. The light emitting diodes 9 of the display unit 4 are covered with a glass plate on which a label is printed for each light emitting diode 9 . The further display unit 5 consists of a conventional four-digit 7-segment light-emitting diode Anzeigevor direction in which all segments that are in the same position, are connected together. The Be operating sequence of this microwave oven control can be configured according to the following explanations.

In Fig. 3, the electrical circuit diagram of the device according to FIGS. 1 and 2 is shown. Of course, the main cooking element of a microwave oven is a magnetron that generates microwave energy. With the magnetron, not shown, a magnetron transformer 10 is connected, which confirms it, when its primary winding is supplied from an AC voltage network 11 with energy. A conventional electrical heating element (resistance heating element) 12 in the oven allows tanning. This heating element 12 is also supplied from the AC mains 11 . A blower motor 13 with associated control lamp is turned on in the oven when the door is closed sen and the on / off switch 6 is turned on. A buzzer 14 outputs a signal when one cycle is completed. The main component of the circuit is a microprocessor 15 in the form of a MOS / LSI semiconductor chip.

The microprocessor 15 receives input data from the keypad 3 or from other input devices, for example from the temperature probe 7 , via four K lines 16 whose inputs are labeled K 1 , K 2 , K 4 and K 8 . There are two different ver, independent output line groups from the microprocessor 15 is provided. One group consists of S- lines 17 whose outputs are labeled S 1 , S 2 , S 3 and S 4 (in fact, the microprocessor 15 could have seven or eight segment outputs, as is typical for computers or other seven segment display devices and one Decimal point are used). The other output line group is formed by D- lines 18 , in which case eleven lines are present whose outputs are denoted by D 0 to D 10 (the chip has in a housing with 40 terminal donate 16 possible D- lines 18 ; less is provided in a conventional 28 pin package). Suitable (not shown) components, such as bipolar transistors, opto-couplers or the like, may connect the various output pins to the display device or to controlled devices when different voltage or current levels are needed, as is conventional. On a Vdd pin is the supply voltage of the microprocessor 15 a Vss pin is grounded. An oscillator input pin Φ forms a frequency control input, if in the microprocessor 15, an internal clock generator is present. For example, in series with the magnetron transformer 10 , the resistance heating element 12 and the blower motor 13 with associated control lamp in series thyristors 19 can be switched by means of couplers 20 . A segment decoder 21 converts a 4-bit BCD code or other code on the S lines 17 (outputs S 1 to S 4 ) into signals on seven lines for driving the segments of the further display unit 5 . The signals generated by the keypad 3 are converted into a code on three lines for input to the microprocessor 15 on the K lines 16 by means of an interface unit 22 .

An embodiment of the microprocessor 15 will now be described. Depending on the complexity of the functions to be executed, the size of the command word memory required for the microprocessor 15 may be 1K or 2K, for example. For example, the microprocessor 15 has the memory capacity 1K.

A block diagram of the microprocessor 15 is shown in FIG . The circuit is grouped around a read only memory 24 (ROM) and a random access memory 25 (RAM). The ROM 24 contains 1024 instruction words of eight bits each; it is used to the memory of the program that actuates the arrangement. The random access memory 25 includes 256 memory cells, software organized as four 16-digit groups of four bits per digit. The random access memory 25 may store information entered via the keypad, intermediate and final results of calculations, state information, flags, and other work data. The random access memory 25 operates as the working register of the circuit, although it is not organized in separate registers from the hardware standpoint, as would be the case if shift registers or the like were used for this purpose. The random access memory 25 is addressed by a word address on lines 26 by a combined address decoder (ROM / RAM word address decoder) 27 , that is, one of 16 word lines in the random access memory 25 is selected. One of four "pages" of the random access memory 25 is selected from an address signal on two lines 28 which is applied to a RAM page address decoder 29 in the random access memory 25 . With a given word address on lines 26 and a page address on lines 28 , access is made to four specific bits output to RAM input / output lines 30 via an input / output circuit 31 to RAM read lines 32 . On the other hand, data is written into the random access memory 25 through the input / output circuit 31 and the input / output lines 30 . The same sixteen lines 26 used as RAM word address lines are also used to generate the display and keypad strobe signals over the D lines 18 . For this purpose, the lines 26 pass through the random access memory 25 and are connected to output registers and to buffers.

The ROM 24 generates, during each instruction cycle on ROM output lines 33, an eight-bit instruction word, with the bits of the instruction word designated R 0 to R 7 . The command is selected from the 8192-bit memory locations in ROM 24 organized in 1024 eight-bit words. The words are divided into sixteen groups or 64-word pages. To address the instruction in ROM 24 , a 1-out-of-64 RAM word address on lines 34 and a 1-out of 16 RAM page address on lines 35 are needed. The ROM word address on lines 34 is generated by the same RAM / ROM address decoder 27 which is also used to generate the RAM word address on lines 26 . The ROM word address is a 6-bit address and is generated in a program counter 36 which consists of a six-stage shift register which can be updated after each instruction cycle and into which via lines 37 from the ROM output lines 33 to perform a Call or branch operation, a 6-bit address can be loaded. The address decoder 27 receives a coded 6-bit address on lines 38 from a decode data selector 39 having two inputs. The decode data selector 39 may receive a 4-bit address from a RAM-Y register 40 via lines 41 or a 6-bit address from the program counter 36 via lines 42 . The program counter 36 is a 6-bit sub-program register 43 is assigned so that it serves as an intermediate memory for the return address word in the course of subroutine operations. In the 6-bit subroutine register 43 , a 6-bit address is stored via lines 44 when a call command is triggered, so that this same address can be reloaded via lines 45 back to the program counter 36 when the subroutine, the the call memory location begins, has been terminated. This preserves the command words and makes programming more flexible. The ROM page address on lines 35 is generated in a page address register ROM page register buffer 46 which is assigned a buffer register 47 for subroutine purposes. The page address register 46 always contains the current page address for the ROM 24 and provides direct access to the ROM page decoder. The buffer register (ROM page register buffer) 47 is a multi-function buffer and buffer register whose contents may be the current ROM page address, another ROM page address, or the return page address during subroutine operations. The program counter 36 , the subroutine register and the ROM page addressing are driven by the control circuit 48 , which receives input signals from the ROM output lines 33 via lines 49 . The control circuit 48 determines whether branches and calls are made to "state" operations or subroutine operations, causes the loading of a command word into the program counter 36 and / or the page address register 46 , controls the transfer of bits to the subroutine or buffer registers and back again, it controls the updating of the program counter 36 , etc.

Numerical data and other information are processed in the circuit by an adder 50 , which is a bit-parallel binary adder equipped with a precharged transfer circuit, that operates in binary and performs software-obtained BCD correction. The input to the adder 50 is determined by an input selector 51 which receives 4-bit parallel inputs from multiple sources and selects from them which inputs are applied to the adder 50 . One of the alternatives is the RAM read lines 32 from the random access memory 25 . Two registers 40 , 52 receive the output signals from the adder 50 . These registers 40 , 52 are the RAM-Y register 40 and an accumulator 52 , each of these registers 40 , 52 having output lines 53 , 54 which are separately closed to the input selector 51 on. A fourth input line 55 receives an output signal from a "constant keypad bit" logic 56 (CKB logic), as will be explained. The adder input is thus selected from the following sources: random access memory 25 via RAM read lines 32 , accumulator 52 via input lines 53 , RAM Y register 40 via input lines 54 and the constant, keypad or bit Information from the CKB logic 56 via the input lines 55 . Positive and negative inputs to adder 50 on lines 57 and 58 are generated by input selector 51 .

The output data of the adder 50 are supplied via lines 59 either the RAM-Y register 40 or the accumulator 52 leads, or they are these two together supplied. All operations of the adder 50 and its input selector 51 and so on are controlled by a control logic field (PLA) data path controller 60 which operates on the ROM 24 depending on the instruction word on the ROM output lines 33 . Control outputs 61 of the data path controller 60 are indicated by dashed lines. The 4-bit output data of the accumulator 52 can be applied via lines 53 to an accumulator buffer register 62 and thus to a segment decoder 63 for output from the circuit. The segment decoder 63 is a programmable logic array which generates on lines 64 up to 8 segment output signals which are applied to a group of 8 output buffers 65 . The output unit includes a memory in the accumulator buffer register 62 so that an output location can be held for more than the duration of a machine cycle. The output is under the control of the data path controller 60 , which operates from the ROM 24 depending on the instruction word on the ROM output lines 33 .

State logic 66 performs the function of checking for carry or equality at adder 50 . It determines whether a branch or a call has to take place. For this purpose, inputs are made from the adder 50 via lines 67 and from the data path controller 60 via lines 61 . The state logic 66 includes a latch that generates outputs on lines 69 to the accumulator buffer register 62 . These output signals can be decoded via the segment decoder 63 in a variety of ways. They can be used to display the decimal point DPT and to select two-digit code groups, such as 7-segment or BCD code groups, from the same programmable logic array. For the decimal point DPT, a BCD code group of the desired decimal point location would be stored in a memory location in the random access memory 25 and compared in the adder 50 with the currently operated D line 18 defined in the RAM Y register 40 . If coincident, the state hold circuit is set and the decimal point DPT is displayed on the display unit for that digit place. In addition, the state hold circuit can be used to demarcate BCD data output signals at certain S- lines 17 and control outputs at other S- lines 17 .

A RAM write controller 70 determines what data will be written or stored in the random access memory 25 via the input / output circuit 31 and the RAM / ROM output lines 30 . This RAM write controller 70 receives input data either via lines 53 from accumulator 52 or via input lines 55 from CKB logic 56 . It generates output data on lines 71 leading to the RAM input / output circuit 31 . The selection of what is written to the random access memory 25 is done by means of the command word on the ROM output lines 33 via the data path controller 60 and the control outputs 61 . An important feature of the arrangement is that constant or keypad information from the CKB logic 56 as well as output data from the adder 50 can be written via the accumulator 52 into the random access memory 25 via the RAM write controller 70 , and further the CKB logic 56 can be used to control the setting and resetting of bits in the random access memory 25 via the RAM write controller 70 .

The RAM page address into which the data is written is determined by two bits of the command word on the ROM output lines 33 which are supplied via lines 72 to a RAM page address register 73 and thus to the RAM side selecting lines 28. *** " Of course, the RAM word or the Y address is selected from the contents of the RAM-Y register 40 , the decode data selector 39, and the ROM / RAM address decoder 27 .

The keypad input data on the four K lines 16 appear on lines 75 , from which an input to the CKB logic 56 is provided. In normal operation, a keypad input signal passes through the CKB logic 56 to the accumulator 52 or the RAM-Y register 40 , from where it is checked by software or ROM programming. In the manufacture of the semiconductor chips, a test operation is possible in which keypad inputs on the lines 75 can be directly input to the ROM page address register 46 . Also, during hardware erasure using the KC input, the signals on the K lines 16 may be input to the RAM page address register 73 . In cases where the device is not used as a computer, a signal on a K line 16 may be used as an interrupt signal.

The microprocessor 15 also includes a clock generator 80 which internally generates a basic clock frequency of about 500 kHz or less and from these five clock signals φ 1 to φ 5 , which are applied throughout the circuit. A power-on cancellation circuit 82 generates control signals which clear the microprocessor 15 when the power is turned on. This can also be supplemented via the KC input with an external capacitor.

The signals used to scan the keypad and display unit on the D lines 18 of the microprocessor 15 are generated from the RAM word address on the lines 26 by means of an output register 84 which is loaded under the control of signals at the control outputs 61 as shown is addressed by the lines 26 . The output data from the output register 84 is supplied via lines 85 to a group of output buffers 86 . While sixteen outputs are possible, in a typical microprocessor 15 implementation only nine to thirteen outputs may be provided, for example eight digits for mantissas, two for exponents and two for digits such as the minus sign for mantissa and exponent.

It is important that the output register 84 be a random access register in which all bits can be addressed individually, independently and mutually exclusively. In the present embodiment, only thirteen stages are provided in the output register 84 , so that only the first thirteen of the sixteen lines 26 are used. When one of the twelve bits in the output register 84 is addressed by the ROM / RAM address decoder 27 , that bit can either be set or reset according to the control signals at the control outputs 61 from the data path controller 60 , ie from the current instruction word. The bit remains set or reset until it is specifically addressed and changed again. Between times, one or all other bits in each order can be addressed and set or reset. It is therefore possible to set or reset any combination of D register bits, giving code combinations on D lines 18 2 13 or 8192. During power up or hardware erase, all bits in output register 84 are unconditionally reset.

Like the output register 84 , the accumulator buffer register 62 is also static in that its contents remain unchanged after input to a deliberate change. The accumulator buffer register 62 operates as an output data buffer while the accumulator 52 and state logic 66 are driven to form the next output data. The output register 84 is just such a buffer for outputting the contents of the RAM-Y register 40 , but has the additional feature of full random accessibility. The following data sources are available to the RAM-Y register 40 : A 4-bit constant stored in the ROM 24 as part of a command word, the contents of the accumulator 52 being input to the RAM Y via the input selector 51 and the adder 50. Register 40 and data directly from the random access memory 25 . Once data is stored in the RAM-Y register 40 , it can be manipulated by additional commands such as "increase" or "decrease".

By means of instructions stored in ROM 24 , each or each combination of S and D output lines 17 and 18 can be actuated independently of any one or a group of K input lines 16 . Thereby, the various segments of the other display unit 5 , the LEDs 9 , the thyristors 19 , the buzzer 14 , etc., can be operated on demand, and the K lines 16 can also be checked as needed. The cycle time of micro-processor 15 for executing an instruction is about 12 to 15 μs, so that hundreds of instructions are executed in a time shorter than that perceived by the operator.

Now, the normal operation of the system described so far will be explained. When the microwave oven is not operating, the microprocessor 15 operates as a clock, storing the time of day in the random access memory 25 by counting the 60 Hz signal. The time of day is given to the further display unit 5 in hours and minutes. To reset the clock, the clock key on the keypad 3 is touched, and the current time is entered as a four-digit hour and minute number by touching the numerical surfaces on the keypad 3 . During this process, the LED associated with the clock 9 lights up in the display unit 4 . Subsequently, the labeled "Start" zone of the keypad 3 is touched, after which the clock works and continuously displays the time of day on the other display unit 5 . The LED 9 lights up when this zone is touched. Subsequently, the time is displayed on the further display unit, unless a cooking process is programmed or is currently running.

Irrespective of all other operations, an alarm timer can be used by touching the zone marked "Alarm" and then entering numbers from 0 to 9 up to a maximum value of 99: 59. By touching the zone "Start" starts a countdown process, the other display unit 5 indicates the remaining time. When the selected period of time has elapsed, the microprocessor 15 actuates the line 17 to the output S 7 , so that the buzzer 14 is driven at a frequency of about 3 kHz for a period of 3 seconds, whereupon the further display unit 5 again to playback the Time of day returns.

Of course, timed cooking is the first Line main interest. The microwave oven is equipped with five sequential programs, each of which is assigned a timer. The Gar programs run in a fixed order:

• (1) thawing,
• (2) automatic temperature adjustment,
• (3) cooking cycle 1,
• (4) cooking cycle 2,
• (5) tan.

However, the cooking commands can be in any order be entered.

When the temperature probe 7 is released from its socket, all five cooking timers are available. Each function is programmed by touching the desired zone 8 of the keypad 3 and by subsequently entering data. Touching another zone 8 or the "Start" zone causes the time data to be stored. For all functions programmed in a sequence, an associated light-emitting diode 9 lights up and remains switched on.

When the door lock is closed, the "Start" zone triggers a given sequence. The timer performing a countdown operation is connected to the further display unit 5 , only its LED being turned on. If the door is opened at any time, the cooking process is interrupted. After closing the door and touching the "Start" zone, the sequence will start again. To terminate a sequence, all of the programming is cleared by touching the "Start" zone and the supply power to the magnetron and heating element 12 is turned off. Subsequently, the reprogramming of the timers is enabled. As soon as a sequence finishes cooking, the buzzer emits 14 tones at a frequency of 3 kHz, lasting 1 second each in a time period of 5 seconds, for a total of 5 minutes. The stop command ends the buzzer signal.

The cook may select a defrost period with a subsequent automatic temperature adjustment period. The defrost timer allows a maximum cooking period of 60: 00 minutes with alternate power cycles and power off cycles, each lasting 15 seconds. This is the first function selected after touching the "Start" zone. If the defrost cycle is not selected, both thawing and temperature setting will be skipped. During the temperature adjustment period, no power is supplied to the magnetron for a period of time consistent with the thawing time. During the setting of the temperature, a light emitting diode 9 is turned on. To use the temperature setting option, the cooking cycle 1 must be programmed.

Two cooking time cycles can be programmed namely the cooking cycle 1 and the cooking cycle 2. The Cooking cycle 1 counts, starting with a maximum of 60: 00 minutes, backward. The cooking cycle 2 counts, starting with maximum 30: 00 minutes, backwards. Optionally, the user can the cooking speed in working cycles of 10% one Select 30-second basic time period (ie. that a duty cycle of 10% the magnetron for the duration of 3 seconds for a total of 30 seconds would). If this option is not selected, becomes a working time for the on-time of the magnetron cycle of 100%.

A typical sequence using the cooking cycle 1 and the cooking cycle 2 is programmed by first touching the "thawing" zone, followed by a period of time, for example, 2-3-0 or 2 minutes and 30 seconds. Subsequently, the zone for the cooking cycle 1 is touched on the keypad 3 , and a time period of, for example, 5-0-0-0, so 50 minutes, is entered. Then, the zone for the cooking cycle 2 is touched, and another period of time is entered by means of the keypad 3 , for example, the time period 1-5-3-0, that is, 15 minutes and 30 seconds. At this time, the actuated LEDs 9 on the display unit 4 are the LEDs for the cooking cycle 1, for the cooking cycle 2 and for thawing. When the "Start" zone is touched, the start and thaw LEDs 9 light up and the display unit displays 2:30. The thawing cycle starts counting backwards from the time of 2:30. After 5 seconds, the start LED goes out. This is followed by a set time of 2 minutes and 30 seconds. The cooking cycles 1 and 2 are standard with an employment ratio of 100%. At the end of the cooking cycle the ready signal sounds and the display unit 4 shows the time of day.

In the presence of the programming just described, the magnetron is switched on with a duty cycle of 100%. In order to change this, the cooking speed button is touched after a cooking time and then a number from 1 to 9 for 10% to 90% have been entered. When this is done, lit on the display unit 4, the LED 9 for the cooking speed. During the cooking cycle, the percentage at the two left places of the further display unit 5 is reproduced every 10 seconds.

In order to obtain a crust on the food, the resistance heating element 12 is controlled by the browning timer. After touching the "tanning" zone on the keypad 3 , a time period of up to 30: 00 minutes can be entered. Following the cooking cycle 2, an associated output, namely the output D 9 , turns on the heating element 12 for the specified period of time.

In many cases, the user may wish to have the cooking takes place at a certain time. The system calculates the time for starting the cooking process, by making all the entered cooking times of the desired Subtracted end time. After touching the zone  for the delayed start, the cook chooses with the help of the digits input assigned zones an end time. Then the Rest of the sequence is set, whereupon the calculation process with an input via the "Start" zone starts. When the time and start time match the cooking process starts automatically. The zone for the delayed start associated LED goes out, and the first cooking timer and associated LED be released. The delayed start he allows a timely finished cooking independently from the cook's presence.

The delayed start also eliminates errors when subtracting minutes and seconds from up to 5 timers. It would be wrong to try to end an hourly episode at 12:30 pm if it were already 12 o'clock. When the desired end time is entered and a sequence of threads is released, the user touches the "Start" zone. The LED for the delayed start then lights up as well as the start LED. The blower motor 13 and associated pilot lamp are turned off. When the start time arrives, the fan motor 13 and associated pilot light are turned on, the delayed start LED goes out, and the selected cooking sequence begins, as indicated in the previous cooking description. When the temperature cooking is enabled, cooking begins 30 minutes before the desired end time.

By using a thermistor in the temperature probe 7 and an analog-to-digital conversion by stepwise approach using multiple, of the S- lines with the outputs S 1 , S 2 , S 3 and S 4 actuated resistors a temperature-controlled cooking is enabled First a check carried out by means of a safety operation in order to ensure that the temperature probe 7 is in its socket. Otherwise, a temperature cooking process could be started while the attachment of the temperature probe 7 in the oven was forgotten. To reach the desired temperature, a maximum time limit of 90 minutes is provided for the temperature probe 7 before the oven automatically stops the cooking process.

When the temperature probe 7 is properly connected and mounted inside the food, the cook closes the door and enters a cooking sequence such as "cook over temperature", then "4", then "cooking speed" etc. or "start".

The programmed temperature is based on a scale from 1 (lowest value) to 9 (highest value). The sensed temperature is displayed on the right side on a scale from 0 to 9. The temperature display is updated once per second. The actual sensed temperature changes with the selection of the probe and the external resistors in the analog-to-digital converter 98 . Every 10 seconds, the cooking speed-related percentage is displayed on the two left-most digits of the display, unless the standard 100% duty cycle option is used. The input to the microprocessor 15 from the analog-to-digital converter 98 via the K line 16 to the input K 2 in binary form. The microprocessor 15 actuates in this way the S- lines 17 with the outputs S 1 to S 4 in various combinations until the signal on the K-line 16 to the input K 2 changes so that a temperature indication is produced.

The described microprocessor 15 is programmed to test the arrangement shown in Figs. 1-3 and also itself while working. This ability can be exploited in multiple ways. The microprocessor 15 can perform an input function test on itself by providing a temporary oven assembly at the test site and plugging each microprocessor as obtained from the oven manufacturer so that it can perform a test sequence without a complicated test setup. Another application is the "burn-in" during oven production. Often, a device is "burned in" after manufacture to ensure that parts that fail after a short turn-on period are found. The Selbsttesteigenschaft can of course also be used for the final test of the furnaces before shipping or retail trade in receipt or sale of the furnace. In addition, the Eigenesteigen shaft can be exploited on the spot by a repair mechanic at home or in a repair shop. It is also possible to guide a customer to check his device at home before calling a repair mechanic.

Two separate Selbsttestmöglichkeiten are provided which can be operated independently. The application of one or both abilities is also possible. The first test routine can be executed without a keypad. It is relatively fast, so it is well suited for initial inspection. The second test route is suitable for the final test and for on-site testing. This test routine uses the keypad 3 , the interface unit 22 , the display units 4 , 5 and all the output devices via the microprocessor 15 .

The first test routine is actuated by connecting the D line 18 to the output D 0 via a line 100 , a diode 101 and a switch 102 to the K line 16 to the input K 4 . The switch 102 is closed before the power supply is applied to the device. If the microprocessor 15 determines that the K line 16 is actuated with the input K 2 , when the D line 18 is actuated with the output D 0 , the test routine begins and the switch 102 can be opened. This means that only one key contact is required. The first test routine consists of these tests, which are performed automatically. The first test operation causes first switching each one of the light emitting diodes 9 for a short period of time, for example, 0.2 seconds. The sequence is "Browning", "Cooking cycle 2", "Cooking cycle 1", "Thawing", Cooking speed, Temperature cooking, "Empty" (S 2 - D 5 overlap), "Temperature setting", "Delayed start", " Clock "," Alarm "and" Start ". Subsequently, starting with the most significant digit, each digit of the other display unit 5 is counted from 0 to 9 at a count rate of about 0.2 seconds. Subsequently, all D and all S lines (with the exception of the S line 17 with the output S 7 , which actuates the buzzer 14 ) are switched on simultaneously. During these three operations, all the LEDs 9 are used in the display unit 4 , all segments at all points of the other display unit 5 and all control outputs (except the buzzer 14 , which is only left out, so that the noise at the test is herabge sets). The system remains in the final state, in which all the control outputs, all light-emitting diodes 9 and display segments are switched on until the supply energy is switched off. This condition is ideal for "burn in".

The second test routine is activated by connecting the output D 0 to the input K 8 via a line 103 , a diode and a switch 104 . This test routine consists of four test operations, of which the first three run automatically after the release, after which the system stops in a hold state until the user starts the fourth operation by means of inputs via the keypad 3 . In the first operation, each of the light emitting diodes 9 lights up successively for a duration of approximately ¼ s. In the second operation, each digit of the display unit 4 , starting with the least significant digit, is counted up from 0 to 9 at a count speed of 0.25 seconds. In the third operation, all of the D and S lines 18 , 17 are turned on, whereupon they terminate with a transition to the hold state. These control output signals are not left on, as they would in the first test routine. The fourth test operation requires the operator to touch the zones 8 of the keypad 3 . When one of the zones 8 is touched and released, the further display unit 5 displays the D line 18 (ie, "2", "4", or "8") that scans the touched key area, and the least significant digit indicates a in the interface unit 22 leading line 85 ' at which the touched key surface is present. The following list shows the display activated for each key-touched area:

Touched zone 8 display Cooking cycle 1 | 2 ·· 1 Start 1 2 ·· 2 1 2 ·· 3 4 2 ·· 4 7 2 ·· 5 Clock 2 ·· 6 thawing 2 ·· 7 Tan 4 ·· 1 0 4 ·· 2 5 4 ·· 4 8th 4 5 ·· Slow cooking 4 ·· 6 Additional timer 4 ·· 7 Gargeschwindigkeit 6 ·· 1 stop 6 2 ·· 3 6 ·· 3 6 6 ·· 4 9 6 ·· 5 Delayed start 6 ·· 6

Each touching a zone 8 of the keypad 3 causes a com bination of D- lines and lines 85 'is activated so that the light emitting diodes 9 of the display unit 4 light up for a period of 0.8 seconds, after which the arrangement back in returns to the state in which all the LEDs of the display unit 4 light up, and from the further display unit 5, the display is played 88: 88 until another zone 8 of the keypad 3 is touched. After the operator has touched all the desired zones 8 (ie tests) and the assembly is in the mode in which all the display units are actuated, the opening of the switch 104 causes disconnection of the K line to the input K 8 to the D line with the output D 0, the return of the arrangement in the normal operation.

Claims (1)

Electronic device having a plurality of electrically controllable assemblies including a display unit associated therewith, a plurality of manually operable input devices for inputting function commands, an on / off switch for controlling the supply of electrical energy, a microprocessor, which is connected to the modules and of the A giveaway receives input signals to a microprocessor associated read-only memory in which are stored instruction words for successively executing operation steps of the apparatus and a control unit in the microprocessor for successively processing the instruction words from the read only memory for driving the modules in response to the function inputted by the input devices are missing, characterized in that the microprocessor ( 15 ) when switching on the device ( 1 ) and in the presence of a release signal at one of its inputs a self-test of Ge device ( 1 ) triggers, in the course of which at least some of the construction groups ( 4, 5, 10, 12, 13 ) automatically controlled one after the other and display elements of the assemblies ( 4, 5, 10, 12, 13 ) zugeord Neten display unit ( 4, 5 ) are activated wherein the on control takes place by executing a sequence of instruction words contained in the read-only memory ( 24 ).