Serial data communication—CAN memory error detection methods
A method is provided for formatting a message, with a first plurality of bits forming a data component, and a second plurality of bits forming a reserved component, for transmission in a vehicle. The method comprises the steps of calculating an initial checksum from the data component, calculating a revised checksum at least from the initial checksum, and storing the revised checksum in the reserved component. The number of bits in the reserved component is less than the number of bits in the data component.
1. A memory for storing data for access by an application program being executed on a data processing system, comprising:
a data structure stored in the memory, the data structure including information resident in a database used by the application program and including:
a data object comprising a plurality of data bits;
an identifier object comprising a plurality of identifier bits represented by at least one integer value; and
a checksum object comprising a plurality of checksum bits reflecting a checksum of the plurality of data bits from the data object with the at least one integer value representing the plurality of identifier bits from the identifier object, and wherein the number of checksum bits is less than the number of data bits.
2. The memory of claim 1 , wherein the at least one integer value is generated by dividing an initial value of the identifier component by a specified divider, such that when this division occurs the integer value will always be a distinct and unique integer value, and such that an increase in the value of the identifier component results in an increase in the value of the at least one integer value.
3. The memory of claim 1 , wherein the plurality of checksum bits in the checksum object reflect at least a checksum comprising a bytewise sum of the plurality of data bytes.
4. The method of claim 1 , wherein the revised checksum is inversely related to the initial checksum and the at least one integer value.
5. The memory of claim 4 , wherein the plurality of checksum bits in the checksum object reflect the subtraction of the checksum and the at least one integer value from a specified value.
6. The memory of claim 5 , wherein:
the checksum includes a specific number of bits; and
the specified value is the maximum checksum number for the specific number of bits.
7. The memory of claim 6 , wherein the ratio of the number of checksum bits to the number of data bits is less than or equal to 1:2.