>> Its just a bread board install and I had to reduce the Spi-Max-Frequency >> due to 10cm long cables. It least I believe it's the cable length. > > What happens if you don't reduce the SPI frequency? CRC Errors above 16Mhz spi frequency. ## No limit $ dmesg | grep -Ei can\|spi [ 30.006596] CAN device driver interface [ 30.276213] spi_master spi0: will run message pump with realtime priority [ 30.436807] mcp251xfd spi0.0 (unnamed net_device) (uninitialized): CRC read error at address 0x0000 (length=4, data=00 07 18 04, CRC=0xb29d). [ 30.436835] mcp251xfd spi0.0 (unnamed net_device) (uninitialized): Controller failed to enter mode Configuration Mode (4) and stays in Internal Loopback Mode (2). [ 30.437036] mcp251xfd spi0.0 (unnamed net_device) (uninitialized): CRC read error at address 0x0000 (length=4, data=00 07 18 04, CRC=0xb29d). [ 30.437261] mcp251xfd: probe of spi0.0 failed with error -74 ## 18Mhz $ dmesg | grep -Ei can\|spi [ 30.345967] CAN device driver interface [ 30.503372] spi_master spi0: will run message pump with realtime priority [ 30.542854] mcp251xfd spi0.0 (unnamed net_device) (uninitialized): CRC read error at address 0x0000 (length=4, data=60 07 18 04, CRC=0xb28c). [ 30.543057] mcp251xfd spi0.0 (unnamed net_device) (uninitialized): CRC read error at address 0x0000 (length=4, data=60 07 18 04, CRC=0xb28c). [ 30.543286] mcp251xfd: probe of spi0.0 failed with error -74 ## 16Mhz $ dmesg | grep -Ei can\|spi [ 29.496863] CAN device driver interface [ 30.028215] spi_master spi0: will run message pump with realtime priority [ 30.171532] mcp251xfd spi0.0 can0: MCP2517FD rev0.0 (-RX_INT +MAB_NO_WARN +CRC_REG +CRC_RX +CRC_TX +ECC -HD c:40.00MHz m:16.00MHz r:16.00MHz e:0.00MHz) successfully initialized. -- Patrick
