FR2506038A1 - Programmable micro-calculator for controlling domestic equipment - contains switching circuit to connect micro-calculator back up power supply when mains supply trips out - Google Patents

Abstract

A power supply, comprising a mains transformer supplying a bridge rectifier, provides a stabilised voltage via a series regulating transistor. A back up power supply comprises a transistor in series with a battery with the transistor collector connected to the power supply rail. A cut out circuit contains a voltage detector comprising a zener diode whose cathode is connected to the regulated power supply rail. This zener provides a voltage when the mains regulates circuit operates. This causes a transistor to conduct and route the power to the micro calculator with its non volatile memory. An initialisation circuit interrupts the base drive to the series transistor in the back up circuit to prevent the battery from discharging when the mains supply is present.

Description

 The present invention relates to control devices, in particular for household electrical appliances, comprising, on the one hand a microcomputer without integrated program memory provided with a volatile memory, associated with a separate non-volatile program memory, on the other hand a mains supply designed to supply said separate non-volatile program memory and the microcomputer without integrated program memory.

An initialization circuit is provided for positioning the initialization input of said microcomputer.

 In control devices of this kind, such as that described in the MOS catalog 1980 of "National Semiconductor", page 1-21, whenever the mains supply is cut, all the data previously written in the volatile memory is disturbed at least partially. It is therefore necessary, after each restoration of the mains supply, to destroy all the data written in the volatile memory. The current program, for example in the household appliance, must therefore always be taken back to its origin, the loss of time being certain, especially when said program is relatively long to perform. This is a downside.

 The control device, object of the present invention, is charac terse embed the initialization circuit comprises means provided so that the positioning of the initialization input of the microcomputer without integrated program memory takes place when the supply voltage of the separate non-volatile program memory drops below the minimum operating voltage of this memory. An emergency power supply is provided, comprising means for ensuring, at this time, its connection, only to the microcomputer. Means for testing the validity of the data stored in the volatile memory of the microcomputer, after restoration of the voltage supplied by the mains supply, ensure, by an initialization program provided in the separate non-volatile program memory, the complete reset to zero of the data in the volatile memory, only in the case where the validity of the data has been tested negative.

 According to one embodiment, the means for testing the validity of the stored data comprise, for example, a cut-off circuit interposed between the power supplies, mains and backup, and the microcomputer, for cutting said feeds when the voltage that these power supplies deliver drops to - below the minimum operating voltage of the microcomputer, so as to erase all the stored data.

The initialization program is intended to test test data written in the volatile memory by a previous execution of the same initialization program.

 According to another embodiment, the means for testing the validity of the stored data comprise a storage circuit provided for detecting and storing the state of the supply voltage of the microcomputer, preceding the return of the mains supply voltage. The initialization program is intended to test, by an input of the microcomputer, the storage circuit, so as to erase all the stored data, in the case where the supply voltage has dropped below the minimum voltage of operation of the microcomputer.

 The present invention makes it possible to produce a control device, which makes it possible to save data stored in a memory, despite a large number of power supply interruptions, while guaranteeing the data stored in said memory. Thus, most of the time, it is not necessary to resume the program in progress, at its beginning. This program can simply be continued, which avoids any loss of time.

 The accompanying drawing illustrates, by way of example, embodiments in accordance with the present invention.

 Fig. 1 shows the electrical diagram of a first embodiment of the invention.

 Fig. 2 represents the flowchart of the initialization program of the same first embodiment.

 Fig. 3 shows the electrical diagram of a second embodiment of the invention.

 Fig. 4 shows the flowchart of the initialization program of the same second embodiment.

 As shown in fig. 1, the first embodiment of the control device comprises a mains supply circuit 8, an emergency supply 7, a cut-off circuit 5, an initialization circuit 6, a microcomputer without integrated program memory 2 and a program memory separate non-volatile 3.

The mains supply 8 comprises a transformer 11, supplied by the mains voltage, the secondary of which is connected to a suppressor capacitor 12 and to a rectifier bridge 13, so as to generate a full-wave rectified voltage, then filtered by a capacitor 14 which is connected to the + and - terminals of said rectifier bridge 13. The rectified and filtered voltage is then stabilized by a transistor 15 whose collector is connected to the + terminal of the rectifier bridge 13 and to a terminal of a resistor 16 whose another terminal is connected to the base of this transistor 15, to a zener diode 17 and to a capacitor 18, so as to supply the base current of the transistor 15 and the current of the zener diode 17. The emitter of this transistor 15 is connected to a capacitor 19, to the anode of a diode 20 and to a + V terminal. The cathode of the diode 20 is connected to a + Vcc terminal. The ground circuit is connected to the terminal - of the bridge 13, to the capacitors 14, 19 and 18 and to the anode of the zener diode 17,
The backup power supply 7 comprises a transistor 31 connected by its base to the resistor 33, and by its emitter to the positive terminal of a battery 30. The ground circuit is connected to the negative terminal of the battery 30. The collector of the transistor 31 is connected to the + Vcc terminal of the mains supply 8. The resistor 33 is connected by its other terminal to a CRM terminal of the initialization circuit 6.

 The initialization circuit 6 comprises a voltage detector device formed by a zener diode 42, the cathode of which is connected to the + V terminal of the mains supply 8, and by a resistor 41 connected between the anode of the zener diode 42 and the ground circuit. A resistor 40 is also connected to the anode of the zener diode 42 and to the base of a transistor 38 whose collector is connected to the base of a transistor 37 and to a resistor 39 connected on the other hand to the terminal. + Vcc from the mains supply 8. The collector of transistor 37 is connected to the CRM terminal, to the + Vcc terminal via a resistor 36, to the ground circuit by a capacitor 35, and to a terminal d 'initialization (reset) input of microcomputer 2. The emitters of transistors 37 and 38 are connected to the ground circuit.

 The cut-off circuit 5 comprises a voltage detector device, constituted by a zener diode 22, the cathode of which is connected to the + Vcc terminal of the mains supply 8, to the emitter of a transistor 28 and, via a resistor 23 at the base of this transistor 28. The anode of the zener diode 22 is connected by a resistor 25 to the ground circuit, and by a resistor 24 at the base of a transistor 26. The base of the transistor 26 is connected by a resistor 29 to the collector of transistor 28 and to a + Vp terminal of the microcomputer 2. The base of transistor 28 is connected by a resistor 27 to the collector of transistor 26 whose emitter is connected to the ground circuit .

 The microcomputer without integrated program memory 2 includes a volatile memory -2 '. It is connected to the separate non-volatile program memory 3 by a mixed bus (data addresses) 10. The separate non-volatile program memory 3 is connected by its + V3 terminal to the + V terminal of the mains supply 8. The microcomputer 2 and the program memory 3 are also connected to the ground circuit.

 Fig. 2 represents the flowchart of the initialization program of the microcomputer 2, contained in a part of the separate non-volatile program memory 3. This program begins with the subroutine 130, for example at address 000 (in the case of COP 402 of National Semiconductor).

This program, using subroutines 131, 132 and 133, is provided for successively testing keys 51, 52 and 53 located in the volatile memory 2 ′ of the microcomputer 2. If these keys are recognized by the subroutines 131, 132 and 133 as good, continuation 134 of the program can be executed. If not previously, a subroutine 135 is executed to reset the volatile memory 2 ′ of the microcomputer 2 and to write the keys 51, 52 and 53.

 When the entire control device is supplied normally from the AC sector by the mains supply 8, not only the microcomputer without integrated program memory 2 is supplied, but also the program memory 3. This supply is made, for the non-volatile memory 3, via the + V terminal of the supply 8, for the microcomputer 2 via the + Vcc terminal of the same supply 8 through the cut-off circuit 5. Indeed, the mains supply 8 then supplies a voltage , on its + Vcc terminal, greater than the threshold voltage of the zener diode 22, increased by the voltage of the base-emitter junction of the transistor 26 which is consequently conductive. Under these conditions, the base current of transistor 28 is established through this transistor 26 and the resistor 27, and the transistor 28 is conductive. The + V terminal is then at a neighboring potential (near a collector-emitter saturation voltage) from that of the terminal + Vcc.

 Simultaneously, in the initialization circuit 6, the transistor 37, bl <r qued by the transistor 38 whose base current is supplied by the voltage of the terminal + V through the zener diode 42, interrupts the base current of the transistor 31 which is thus blocked, which prevents the battery 30 of the emergency power supply circuit 7 from delivering to the + Vcc terminal. Similarly, the reset terminal of the microcomputer 2, positioned by the resistor 36 at the potential of the spindle + Vcc does not interfere with the operation of the washer-extractor 2. It normally executes the program located in memory 3.

 The overall consumption is then equal to the sum of the consumptions of the microcomputer without integrated program memory 2 and of the separate program memory 3. For example, when using a COP 402 microcomputer from National Semiconductor and a program memory MM 2716 Q from the same manufacturer, the overall consumption is close to 545 mW, respectively 45 mW, 500 mW.

 When the supply voltage of the + V terminal becomes insufficient, this voltage being exclusively supplied by the AC sector which then fails, the initialization circuit 6 carries the reset input of the microcomputer 2 to a potential close to that of the mass. Indeed, if the voltage of the terminal + V drops below the threshold voltage of the zener diode 42, increased by the voltage of the base-e-emitter junction of the transistor 38, the transistor 38 is blocked. The transistor 37 then becomes conductive and "positions" the reset terminal of the microcomputer 2 at a voltage close to zero.

 It should be noted that the voltage detection carried out by the initialization circuit 6 is made from the voltage of the terminal + V, supplied exclusively by the mains supply 8. In fact, the diode 20 located in the circuit mains supply 8 prevents the + V terminal from being supplied by the emergency supply circuit 7.

The initialization circuit 6 also controls through the terminal
CRM the conduction of the transistor 31 so that the battery 30 flows on the terminal + Vcc to supply the microcomputer 2.

 The reset input of the microcomputer 2, positioned by the initialization circuit 6, as described above, stops the normal operation of the microcomputer 2. Its ordinal counter is forced for example at address 000 (in the case of COP 402) and the microcomputer 2 no longer uses the data coming from the program memory 3 which is then insufficiently supplied.

 Under these conditions, the data contained in the volatile memory 2 ′ of the microcomputer 2 is not disturbed. The overall consumption is then reduced to that of the microcomputer without integrated program memory 2, which in our example is 45 mW. This reduced consumption makes it possible to obtain a long (charged) lifetime for the battery 30 of the emergency power supply circuit 7.

 When the mains voltage returns, when the supply voltage of the program memory 3 becomes sufficient, that is to say greater than the threshold voltage of the zener diode 42, the initialization circuit 6 cancels the command on the reset input of the microcomputer 2. The microcomputer 2 executes the program contained in the non-volatile program memory 3 starting with the subroutine 130 starting, in the case of our example (COP 402), at address 000. The program executed is described by the flowchart in fig. 2. This program first of all tests, in the volatile memory 2 ′ of the microcomputer 2, the keys 51, 52, 53 to verify the validity of the data contained in this volatile memory 2 ′.

 In the case where, during the power cut, the microcomputer 2 was supplied by the emergency power supply circuit 7 through the cut-off circuit 5, the data contained in the volatile memory 2 'have not been modified and the keys 51, 52, and 53 are tested good by the subroutines 131, 132 and 133, and the program contained in the program memory 3 can continue normally.

 In the case where, during the cut-off period of the mains voltage, the voltage + Vcc supplied by the emergency supply 7 is insufficient, the cut-off circuit 5 cuts off the supply to the microcomputer 2. In fact, if the voltage + Vcc is lower than the threshold voltage of the zener diode 22, increased by the voltage of the base-emitter junction of the transistor 26, this transistor is blocked, interrupts the base current of the transistor 28 which is blocked and cuts the power supply of the microcomputer 2.

 The purpose of the resistor 29 is to cause a hysteresis on the operating voltage of the cut-off circuit 5 so as to guarantee a minimum cut-off time given by the time constant of the mains supply 8, and to ensure that all the data contained in the volatile memory 2 'are destroyed.

 When the AC mains voltage returns, the subprograms 131, 132 and 133 test the bad keys 51, 52 and 53, and the subprogram 135 executes a normal initialization subroutine with a reset to zero data from volatile memory 2 'and the writing of keys 51, 52 and 53.

 This device therefore makes it possible to save the data stored in a microcomputer, with reduced consumption, while guaranteeing the validity of this data.

 Fig. 3 shows a second embodiment of the control device, in accordance with the present invention. The cut-off circuit 5 of the first embodiment (fig. 1) is replaced by a circuit 9 for memorizing the state of the supply.

 This circuit 9 comprises a voltage detector constituted for example by a zener diode 76 and a resistor 77. The cathode of the zener diode 76 is connected to the + Vcc terminal of the mains supply 8, the anode of this zener diode 76 being connected to the ground circuit by resistor 77 and at the base of a transistor 79 by a resistor 78. The transistor 79 has its emitter connected to the ground circuit, and its collector connected to the cathode of a diode 75. A transistor 70 has its base connected to the cathode of a diode 73, the anode of this diode 73 being connected by a resistor 74 to the + Vcc terminal of the mains supply 8, and to the anode of the diode 75. The circuit of ground is also connected to the emitter of transistor 70 and to a capacitor 72. The collector of transistor 70 is connected to a terminal in tréer. from the microcomputer 2, to the capacitor 72 and, by a resistor 71, to the terminal + Vfl. of the microcomputer, itself connected to the + Vcc terminal of the mains supply 8.

 All the other constituent elements are identical to those of the first embodiment (FIG. 1). Fig. 4 represents the flowchart of the initialization program, of the microcomputer 2 contained in a part of the separate non-volatile memory 3, in the case of this second embodiment. This program begins with subroutine 60 at address 000 and, using subroutine 61, tests the input ffi of microcomputer 2.

Depending on the result of this test, this subroutine 61 addresses the sequence 62 of the program, or the subroutine 63 for resetting the volatile memory 2 ′ to then also execute the sequence 62 of the program.

 In this second embodiment, the operation of circuits 6, 7 and 8 remains identical to that described above (fig. 1).

 The role of circuit 9 is to detect and store the state of the supply voltage of microcomputer 2, preceding the return of the mains supply voltage. The detection of this state is ensured by the zener diode 76, the resistors 77 and 78, and the transistor 79. The memorization of this state is carried out by the capacitor 72. In fact, if the voltage of the terminal + Vb is maintained by 11 emergency power supply 7, during the power cut, at a value greater than that of the threshold voltage of the zener diode 76, the transistor 79 remains saturated and blocks the transistor 70. The transistor 70 therefore does not intervene under these conditions on the charge of the capacitor 72 which can memorize the normal state of the voltage on the + V terminal. The potential of the inputs # is therefore close to that of the + VF terminal and the subroutine 61, testing the high level of this entry commands the execution of the sequence 62 of the program. In the case where the voltage of the terminal + Ve is not maintained by the emergency power supply 7, during the power cut, at a value greater than the threshold voltage of the zener diode 76, the transistor 79 is blocked . When the voltage supplied by the mains supply 8 returns to the + Vcc terminal, the transistor 79, being blocked, "authorizes" the establishment of a base current for the transistor 70 through the resistor 74 and the diode 73 .

This transistor 70 therefore saturates and discharges the capacitor 72 which stores the insufficient state of the voltage on the + V terminal. The potential of the inputs is close to zero and the subroutine 61, testing the low level of this input, commands the volatile memory reset subroutine 63 'before executing the sequence 62 from the program.

 The control devices, object of the invention, can be used in particular to control electrodomgstic devices such as dishwashers, washing machines, water softeners, etc.

Claims (3)

1. Control device, in particular for household electrical appliances  ques, comprising, on the one hand a microcomputer without program memory  integrated (2), provided with a volatile memory (2 '), associated with a memory  separate non-volatile program (3), on the other hand a mains supply  (8) designed to supply the separate non-volatile program memory (3)  and the microcomputer without integrated program memory (2), a circuit  initialization (6) being provided to position the initialization input  tion (reset) of the microcomputer (2), characterized in that the circuit  initialization includes means provided for positioning  the initialization (reset) input of the microcomputer (2) is carried out  when the supply voltage of the separate program memory is not  volatile (3) drops below the minimum operating voltage  ment of this memory (3), a backup power supply (7) comprising  means to ensure, at this time, its connection, only in mid  crocalculateur (2), means for testing the validity of sto data  ckées in the volatile memory (2 ') of the microcomputer (2), after reta  loss of voltage supplied by the mains supply (8), assu  rant, by an initialization program provided in the program memory  separate non-volatile (3), the complete reset of the data of the  volatile memory (2 '), only if the validity of the donations  born was tested negative. 2. Control device according to claim 1, characterized in that  the means of testing the valldite of the stored data includes a  cut-off circuit (5) interposed between the power supplies, sector (8)  and backup (7), and the microcomputer (2), for cutting said a  power supplies when the voltage that these power supplies deliver drops  below the minimum operating voltage of the microcomputer  (2), in order to erase all the stored data, the i program  nitialization being provided for testing test data written to  volatile memory (2 ') by a previous execution of the same program  initialization. 3. Control device according to claim 1, characterized in that  the means for testing the validity of the stored data include a  storage circuit (9) designed to detect and store the state of  the supply voltage of the microcomputer (2), preceding the return  of the mains supply voltage, the initialization program  both provided for testing, by an input (P) of the microcomputer (2), the  memory circuit (9), so as to erase all the sto data  ckées, if the supply voltage has dropped below the minimum operating voltage of the microcomputer (2).