In this method, on a DMA transfer-done interrupt,
data coherency can be checked. The data packet can include an expected CRC value. In
software, a CRC is computed and checked against the expected CRC.
Note: Medium coverage can be claimed under the
following circumstances:
- Medium overall coverage of failure modes in data transmission; a Hamming
distance of three or more.
- A CRC value for message information is embedded in message; with a CRC size
of 8 bits and a 0x97 polynomial results in a Hamming distance of four for a
data length of less than 119 bits. The transmitter includes the CRC value
mentioned and the receiver confirms the data after calculating and comparing
the CRC value (typically used in a LIN bus).
- A CRC value for message information and message ID is embedded in the
message; with a CRC size of 10 bits and a 0x319 polynomial results in a
Hamming distance of four for a data length of less than 501 bits. The
transmitter includes the CRC value mentioned and the receiver confirms the
data after calculating and comparing the CRC value.
- A CRC value for message information and message ID is embedded in the
message; with a CRC size of 15 bits and a 0x4599 polynomial results in a
Hamming distance of five for a data length of less than 127 bits.
Additionally, burst errors of a length up to 15 can be detected. The
transmitter includes the CRC value mentioned and the receiver confirms the
data after calculating and comparing the CRC value (as used in CAN).
- A CRC value for message information is embedded in the message, with a CRC
size of 24 bits and a 0x5D6DCB polynomial results in a Hamming distance of
the CRC of six for a data length of less than, or equal to, 248 bytes and a
Hamming distance of the CRC of four for a data length of greater than 248
bytes. The transmitter includes the CRC value mentioned and the receiver
confirms the data after calculating and comparing the CRC value (as used in
FlexRay™ for the frame
CRC).
- A CRC value for message header (including the message ID) is embedded in the
message; with a CRC size of 11 bits and a 0x385 polynomial results in a
Hamming distance of six for a data length of less than, or equal to, 20
bits. The transmitter includes the CRC value mentioned and the receiver
confirms the data after calculating and comparing the CRC value (as used in
FlexRay™ for the header CRC).