GD32A50x User Manual
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DATA field of a matched message is the same as the configured expected DATA field in
CAN_PN_EDLx (x = 0,1) registers, using filter data in CAN_PN_DF0EDH0 and
CAN_PN_DF1EDH1 registers.
When DATAFT[1:0] bit field in CAN_PN_CTL0 register is configured to 1, it means the
DATA field of a matched message is larger than or equal to the configured expected
DATA field in CAN_PN_EDLx (x = 0,1) registers. CAN_PN_DF0EDH0 and
CAN_PN_DF1EDH1 registers are reserved.
When DATAFT[1:0] bit field in CAN_PN_CTL0 register is configured to 2, it means the
DATA field of a matched message is smaller than or equal to the configured expected
DATA field in CAN_PN_EDLx (x = 0,1) registers. CAN_PN_DF0EDH0 and
CAN_PN_DF1EDH1 registers are reserved.
When DATAFT[1:0] bit field in CAN_PN_CTL0 register is configured to 3, it means the
DATA field of a matched message is larger than or equal to the configured expected
DATA field in CAN_PN_EDLx (x = 0,1) registers, and is smaller than or equal to the
configured expected DATA field in CAN_PN_DF0EDH0 and CAN_PN_DF1EDH1
registers.
Note:
In this case, all the two 8 bytes of the expected data register should be configured,
when the DLC of the received message (DLC field matched) is less than 8 bytes, then in
DATA field matching, the data that matching with the expected data is the received DATA
field plus the padding value zeros.
23.3.8.
CAN FD operation
Both ISO CAN FD (ISO11898-1 specification) and non-ISO (Bosch CAN FD Specification
V1.0) CAN FD protocols are supported, but they are incompatible with each other, so select
the protocol by ISO bit in CAN_CTL2 register. In comparison to the non-ISO CAN FD protocol,
a 3-bit counter and a parity bit are introduced in ISO CAN FD protocol. Thus the failure
detection capability is improved for ISO CAN FD.
CAN FD mode supports both CAN classical frames and CAN FD frames. The FDF bit (the
reserved bit in CAN classical frames) is used to distinguish between CAN classical and CAN
FD format frames. When the FDF bit is recessive ‘1’, it is recognized as a CAN FD frame;
otherwise, it is a classical frame. Compared with CAN classical frame, CAN FD frame does
not support Rx FIFO, Rx FIFO DMA, and Pretended Networking function.
To enable CAN FD mode, set FDEN bit in CAN_CTL0 register to 1.
CAN FD BRS
In CAN FD mode, the data byte length is allowed up to 64 bytes for a CAN FD frame, and the
bit time can switch to a higher speed of 8 Mbit/s for the Data Phase (from BRS bit to the first
sample point of CRC Delimiter or to the starting of an error frame when an error condition is
detected) of a CAN FD frame with BRS bit set
(refer to ISO11898-1 or Bosch CAN FD
Specification V1.0).