Externally reprogrammable vehicular microcomputer with hardware lock-out of unauthorized memory modifications
First Claim
1. An externally reprogrammable computer system, responsive to an external programming unit (P,1), for an automotive vehicle (5) having a control unit (2) includinga microprocessor or computer (23);
- a non-volatile, read-only programmable memory (EEPROM) (25) permanently connected to the computer (23) and addressed by the computer for entry of data into the memory and for retrieval of data from the memory for carrying out computation operations by the computer,means (24) interconnecting said microprocessor and memory;
means (26) transmitting operating data from the vehicle to the computer (23);
means (27) for transmitting computed data from the computer to the vehicle, for controlling vehicle operations in accordance with the computed data,the computer receiving the operating data and computing the control data based on the received operating data and on data stored in said memory (25),comprisingreprogramming authorization and transmission means (13,11,12,21,22) includingan interface (3, 11,
12) connecting the external programming unit (1) to the microprocessor (23) in the control unit (2) and signaling said programming unit when data have been accurately transmitted over the interface;
means in said memory (25) making said memory normally non-responsive to writing instructions from said microprocessor and to any stray voltages on said means (24) interconnecting said microprocessor and memory; and
a release-enable bus (13) coupled from said external programming unit (1) through said interface to the memory (25) and authorizing writing of new program data into the memory only when said external programming unit has received from said interface (3) an "accurate transmission" signal.
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Accused Products
Abstract
To prevent change of data in a non-volatile programmable, ready-only memory (25) forming, together with a microprocessor (23) a control unit, for example for an automotive vehicle, while permitting programming of the memory from an external programming unit (P, 1), an interface (3, 11, 12) is provided through which a release-enable bus (13) also passes, data being transmitted in accordance with a predetermined characteristic--even or odd parity--, the parity correctness being checked. If the parity is correct, an "enter" signal is provided on the release-enable bus for storing the data; if not, retransmission is attempted for a predetermined number of time, and if it cannot be correctly effected, a malfunction indication output signal is generated.
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Citations
16 Claims
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1. An externally reprogrammable computer system, responsive to an external programming unit (P,1), for an automotive vehicle (5) having a control unit (2) including
a microprocessor or computer (23); -
a non-volatile, read-only programmable memory (EEPROM) (25) permanently connected to the computer (23) and addressed by the computer for entry of data into the memory and for retrieval of data from the memory for carrying out computation operations by the computer, means (24) interconnecting said microprocessor and memory; means (26) transmitting operating data from the vehicle to the computer (23); means (27) for transmitting computed data from the computer to the vehicle, for controlling vehicle operations in accordance with the computed data, the computer receiving the operating data and computing the control data based on the received operating data and on data stored in said memory (25), comprising reprogramming authorization and transmission means (13,11,12,21,22) including an interface (3, 11,
12) connecting the external programming unit (1) to the microprocessor (23) in the control unit (2) and signaling said programming unit when data have been accurately transmitted over the interface;means in said memory (25) making said memory normally non-responsive to writing instructions from said microprocessor and to any stray voltages on said means (24) interconnecting said microprocessor and memory; and a release-enable bus (13) coupled from said external programming unit (1) through said interface to the memory (25) and authorizing writing of new program data into the memory only when said external programming unit has received from said interface (3) an "accurate transmission" signal. - View Dependent Claims (2, 3, 4, 5)
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6. Method of assuring data integrity in the memory (25) of an on-board vehicular microcomputer system, forming a part of a control unit (2), before and during programming thereof by a separate external programming unit (1), said control unit (2) having a computer or microprocessor (23),
a memory (25) connected in data exchange relation with said microprocessor (23), an interface (3, 11, 12) connected during operation to said external programming unit (1), a data bus (11, 12), interconnecting said interface (3) and said microprocessor (23), and a release-enable bus (13) interconnecting said interface and said memory, said memory (25) responding to writing signals only when said release-enable bus is energized and "locking out" writing signals at all other times, comprising the steps of transmitting, on said data bus, between the programming unit (1) and the computer, data having a predetermined characteristic; -
analyzing the data, in that one (2) of the units which is receiving data, for correctness of the characteristic; and
providing on said data bus (12), selectively;(a) if the characteristic is correct, a "correct" signal; (b) enabling the release-enable bus (13) for storage of the data in the memory (25) only if said correct signal is present; and (c) continuing transmission of data;
or(d) if the characteristic is incorrect, an "error" signal to that one of the units which was transmitting the data; and (e) entering an "error transmission" subroutine until correctness of the characteristic is detected and terminating transmission if, after a predetermined number of incorrect transmissions, no correct characteristic is detected. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification