Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle diagnosis or maintenance indication
Patent
1995-07-13
1999-01-05
Zanelli, Michael
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle diagnosis or maintenance indication
701115, G05B 19042
Patent
active
058571582
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a control unit including a microcomputer and a programmable nonvolatile memory and, more particularly, to a motor vehicle control unit including a microcomputer and programmable nonvolatile memory.
A control unit and a device for programming it are already known from EP 0 266 704 A2. In this case an external programming unit is provided for programming the nonvolatile memory of the control unit. The external programming unit is connected to the control unit via a serial transmission line. The data to be programmed are transmitted to the control unit via this serial transmission line. The microcontroller of the control unit receives the data and then programs them into the nonvolatile memory to be programmed. To this end, the necessary programming voltage is fed to the control unit via a separate connection between the programming unit and control unit. Therefore, there is a separate input pin provided at the control unit, to which input pin the programming voltage can be applied from the outside.
It is also known to generate the programming voltage internally in the control unit. The programming process is initiated using control instructions which are transmitted to the control unit via the serial transmission line. It is disadvantageous here that as a result of electromagnetic interference the program sequence of the control unit may be arbitrarily altered so that it is not ensured that the programming of the nonvolatile memory cannot be initiated wrongly.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a control unit and device for programming it of the above-described types that do not have the above-described disadvantages.
According to the invention the control unit comprises microcomputer, transmission line is connectable over which data for programming the programmable nonvolatile memory is received in the microcomputer from an external programming unit, and transmission line, the low pass filter including means for producing a signal for enabling the programming of the programmable nonvolatile memory if the external programming unit is connected to the control unit via the at least one serial data transmission line.
The control unit according to the invention has, in contrast, the advantage that, on the one hand, it is not necessary to provide an additional control-unit pin for enabling the programming at the control unit and, on the other hand, arbitrary initiation of the programming of the nonvolatile memory of the control unit cannot be triggered by a fault in the program sequence of the control unit.
Advantageous developments and improvements to the control unit disclosed in the main claim are possible by virtue of the measures specified in the subclaims. Furthermore, the advantages of the device according to the invention for programming the control unit according to the invention are disclosed.
It is particularly advantageous that the enabling signal for the programming is extracted from the serial transmission line via a low pass filter consisting of a resistor and capacitor. As a result, it is possible for the enabling signal to continue to be present at the memory even during a data transmission and for the sequencing of the programming to take place independently of the transmission of data via the serial transmission line.
It is also advantageous that a resistor is connected to ground downstream of the low pass filter between the capacitor and the programming-enabling input of the nonvolatile memory.
It is particularly advantageous when the signal for enabling programming is input to a charging pump that applies a programming voltage to the nonvolatile memory in response to that signal if the nonvolatile memory requires a higher voltage (e.g. 12 V) for the programming process.
Furthermore, it is advantageous that an input resistor is connected to the transmission line in the control unit, which input resistor is connected at the other end to the supply voltage line (ground). As a result it is e
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Grote Walter
Zimmermann Jurgen
Robert & Bosch GmbH
Striker Michael J.
Zanelli Michael
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