SPRUJ53B April 2024 – September 2024 TMS320F28P550SJ , TMS320F28P559SJ-Q1
A checksum error (CE) is detected and flagged at the receiving end, if the calculated modulo-256 sum over all received data bytes (including the ID byte if the enhanced checksum type) plus the checksum byte does not result in 0xFF. The modulo-256 sum is calculated over each byte by adding with carry, where the carry bit of each addition is added to the LSB of the resulting sum.
For the transmitting node, the checksum byte sent at the end of a message is the inverted sum of all the data bytes (see Figure 1-1) for classic checksum implementation. The checksum byte is the inverted sum of the identifier byte and all the data bytes (see Figure 29-23) for the LIN 2.0 compliant enhanced checksum implementation. The classic checksum implementation can always be used for reserved identifiers 60 to 63; therefore, the CTYPE bit is overridden in this case. For signal-carrying-frame identifiers (0 to 59) the type of checksum used depends on the CTYPE bit.