Describe CubeMX settings

README.md

@@ -42,3 +42,36 @@ cDefinitions:
 4. To transmit messages, call `ftcan_transmit()`
 5. When a message is received, `ftcan_msg_received_cb()` is called. It has a
    default empty implementation, which you can simply override.
+
+## Enabling CAN in STM32CubeMX
+
+This isn't specific to `can-halal`, but for completeness sake is included here.
+
+### bxCAN (e.g. STM32F3xx)
+
+1. Enable the CAN peripheral  
+   ![Connectivity -> CAN -> Activated](doc/bxcan-activate.png)
+2. Setup the [bit timings](http://bittiming.can-wiki.info/).  
+   **Note:** the baud rate depends on your system clock, so make sure that is
+   setup correctly first!  
+   ![Connectivity -> CAN -> Parameter Settings -> Bit Timings Parameters](doc/bxcan-bittimings.png)
+3. Make sure the CAN_RX0 interrupt is enabled  
+   ![Connectivity -> CAN -> NVIC Settings -> CAN_RX0 interrupt](doc/bxcan-interrupt.png)
+
+### FDCAN (e.g. STM32H7xx)
+
+1. Enable the CAN peripheral  
+   ![Connectivity -> FDCAN(1)](doc/fdcan-activate.png)
+2. Setup the frame format, nominal SJW, filters, and FIFOs. The numbers for
+   filters/FIFOs in the screenshot are examples.  
+   **Note:** You need to tell `can-halal` about the number of filters by
+   defining `FTCAN_NUM_FILTERS` (see above).  
+   ![Connectivity -> FDCAN(1) -> Parameter Settings -> Basic Parameters](doc/fdcan-basic.png)
+3. Setup the [bit timings](http://bittiming.can-wiki.info/). We only use CAN in
+   classic mode, not FD mode, so we only need to worry about the nominal bit
+   timings  
+   **Note:** the baud rate depends on your system clock, so make sure that is
+   setup correctly first!  
+   ![Connectivity -> FDCAN(1) -> Parameter Settings -> Bit Timings Parameters](doc/fdcan-bittimings.png)
+4. Make sure the interrupts are enabled
+   ![Connectivity -> FDCAN(1) -> NVIC Settings](doc/fdcan-interrupt.png)