43.5.2 Clocks

The CAN bus clock (CLK_CAN_APB) can be enabled and disabled in the CRU. A generic clock (GCLK_CAN) is required to clock the CAN. This clock must be configured and enabled in the generic clock controller before using the CAN. For more details, see Clock and Reset Unit (CRU) from Related Links. One possible configuration is to use the UPLL/EPLL and a REFO divider to achieve the required clock frequency. This generic clock is asynchronous to the bus clock (CLK_CAN_APB). Due to this asynchronicity, writes to certain registers requires synchronization between the clock domains.

Note: Regardless of which clock source is used for the CAN, the CAN must receive a 20, 40 or 80 MHz clock to ensure compatibility with other CAN devices.

Note: The CAN IP requests clocks even when it is in reset; therefore, any clock requests from the CAN macro must be gated off with the peripheral enable.