Abstract:
Proposed is a method for programming and/or testing for the correct functioning of an electronic circuit, and a corresponding device, which is used to efficiently program and test electronic circuits combined on a wafer, prior to their separation. For this purpose, a bus allowing the individual electronic circuits to be sequentially tested is positioned on the wafer. Each electronic circuit is assigned an address for the bus, using a hardware code. The address is deactivated after completion of the functionality and testing method.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a method for programming and/or testing the correct functioning of an electronic circuit. 
   SUMMARY OF THE INVENTION 
   The method of the present invention for programming and/or testing the correct functioning of an electronic circuit, and the corresponding device for implementing this method have the advantage that the idea of panel testing is implemented during the manufacturing of electronic circuits, and the cycle time during production is therefore reduced. A panel is generally understood to mean a large printed circuit board, which has several, substantially identical, electronic circuits, which are separated from each other after the programming and the functional testing. The method of the present invention and the device of the present invention allow electronic circuits connected in this manner to be programmed one after another and tested for correct functioning, by assigning them an address. The addressing of the specific electronic circuit is ultimately switched off, since it is no longer necessary for the further operation of electronic circuit. In this case, an electronic circuit is particularly understood to mean a control unit, but other programmable, electronic circuits, which may contain microprocessors, may be used here. The programming is accomplished by a connected device, which then also takes over the functional testing. The electrical connection between the electronic circuits allows this device to be connected. This electrical connection may advantageously take the form of the bus. However, individual lines may also lead to the individual electronic circuits of the panel. 
   It is particularly advantageous that, as mentioned above, the electronic circuits are arranged together on an electronic circuit board, the electrical connection between the electronic circuits and the electrical connection for attaching the test device being realized by a simple bus. A parallel bus is preferably used here. Therefore, the individual electronic circuits of the panel may be sequentially addressed as a function of the address. 
   In addition, it is advantageous that the address of the specific electronic circuit is reached, using an appropriate hardware code. This hardware code is situated in the electronic circuit, and in this case, it is preferably defined by a resistance code or parts of the test circuit. Short-circuiting links on the edge of the panel or binary codes are also conceivable alternatives to the resistance code. In the case of the binary codes, individual signals may be provided, in particular, on the panel edge at ground, while others are provided at the supply voltage. 
   Furthermore, it is advantageous that, in the event of an incorrect address determination, which, for example, is not able to be carried out because of a hardware fault, the electronic circuit assigns itself an address, which prevents the device from addressing it. This prevents a faulty circuit from blocking the communications bus and holding up production. 
   After the method is terminated, the address may advantageously be switched off by using a password, which the device retrieves, and which is checked by the individual electronic circuits. 
   Finally, is also advantageous that, in addition to the data connection via the bus, which may be used alternatively in addition to the power supply as well, the electronic circuits are connected to at least one power-supply line. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a block diagram of the device according to the present invention. 
       FIG. 2  shows a flow chart of the method according to the present invention. 
   

   DETAILED DESCRIPTION 
   The increasing use of control units necessitates the development of efficient production methods and start-up methods. The present invention proposes a method for programming and/or testing for the correct functioning of an electronic circuit, i.e. for example a control unit, which may be implemented on a panel, i.e. when several electronic circuits are situated on a common, printed circuit board. This is achieved by a bus, which is only attached to the printed circuit board for this reason. Instead of a bus, individual lines may also lead to the different electronic circuits, these individual lines also allowing the connection of a test device. 
   Therefore, such a printed circuit board panel is fitted with several control unit. These are powered via the panel edge, e.g. using a supply line and a ground line, and are connected to a test computer, i.e. the device, by a so-called K-line bus. To test the panel on the K-line bus, it is imperative that each control unit have a unique K-line address. In order for it to be able to assign each control unit a separate address, each control unit has an individual hardware testing circuit on the panel edge, by which it may determine its address. When the control units are separated from the panel, this test circuit may subsequently be separated out with the waste material. The address determination, which is achieved by supplying electrical energy via the supply line, starts immediately after the control units are switched on. 
   The test circuit for determining the address is situated on the panel edge and is made up of two resistors per control unit. After the control unit is switched on, the control unit checks at which inputs there are test resistances in the expected resistance range. Each control unit determines its address, based on the position of the detected test resistances. To determine an address, it is ascertained that just exactly two resistors are present and a valid combination of resistor positions is present. If the address cannot be determined unequivocally, e.g. due to a hardware error, then the control unit assigns itself address 00. Consequently, it is no longer addressed in later tests and may not interfere with the K-line bus. 
   In addition, a fuse, which keeps a short-circuit of an individual control unit from preventing the testing of the entire panel, is built into the supply line of each control unit. The addressing of the panel may be switched off by writing a password into the memory. In this case, an EEPROM is used as a memory. This is done as the last testing step prior to sectioning the panel. If a bus is used, then the connected, electronic circuits have a bus driver, in order to be able to communicate via the bus. In other words, they have transmitting-receiving units, i.e. transmitter-receiver chips. In the case of individual lines that lead to the test apparatus, the control units also have transmitting-receiving units, in order to be able to communicate via the line. Even the test device has such units of communication. 
     FIG. 1  shows a block diagram of the device according to the present invention. Represented is a panel on which control units  1 ,  6 ,  9 , and  20  are situated. Control unit  1  has two attached resistors  2  and  3 , control unit  20  has resistors  4  and  5 , control unit  6  has resistors  7  and  8 , and control unit  9  has resistors  10  and  11 . These resistors determine the address of each individual control unit. Using a bus  13 , which is designed here to be a parallel bus, the control units are connected as bus stations to a device  12  that functions as a test computer. In addition, control units  1 ,  6 ,  9 , and  20  are connected by a power-supply line  15  to a power supply  14 . It is also possible for control units  1 ,  6 ,  9 , and  20  to be supplied with power by bus  13 , so that a power-line transmission is then used in this case. 
     FIG. 2  shows a flow chart of the method according to the present invention. In method step  16 , electrical energy is supplied to control units  1 ,  6 ,  9 , and  20  by power supply  14 , via line  15 . As mentioned above, it is alternatively possible to supply power to control units  1 ,  6 ,  9 , and  20  via bus  13 . In this case, test computer  12  then functions as a master. It is alternatively possible to use a multi-master system, as is known from the CAN bus. In a master-slave system, as is used in this case, individual control units  1 ,  6 ,  9 , and  20  are subordinated to test computer  12  as slaves. After electrical power is supplied, each control unit  1 ,  6 ,  9 , and  20  sets its address on the basis of the connected resistors, as shown in method  17 . If this address determination is successful, i.e. if the detected resistance values are in the expected range, then the method goes on to method step  21 . But if it is established in method step  18 , that this address could not be correctly determined, then the control unit in question assigns itself the address 00 in method step  19 , which causes this control unit not to be addressed by test computer  12  during the programming and the functional test. 
   In method step  21 , the sequential addressing is then accomplished as a function of the address of the individual control unit, using test computer  12 . In this context, the individual control units are programmed in their memory. At the beginning, all of control units  1 ,  6 ,  9 , and  20  had the same memory state, and no parameters were programmed. After the addressing is carried out by the individual control units, a control character is transmitted on the bus by, namely, test computer  12 , so that only the control unit, whose address corresponds to this control character, reacts to it. If the corresponding control unit is activated, then, in method step  22 , communication is established, using a normal factory airbag diagnosis, and a set of parameters is programmed into the control unit. At the end of the programming, a further control character is transmitted, which is the same for all of the units, so that the communication is ended by ending the factory-diagnosis mode, as well. A further control character is then transmitted, which activates the corresponding control unit, and the same operation is repeated until the entire panel is processed. After the programming, the functional test may be continued in order to finally conclude with the method and switch off the address in method step  23 . The disconnection is accomplished by writing a password into the memory, after which the panel is then sectioned. A further refinement may provide for a fuse being installed in the supply line of each electronic circuit, the fuse keeping a short-circuit of an individual electronic circuit from preventing the testing of the entire panel.