To allow the system to determine baud rates of the received characters, the UxRX input can be internally connected to a selected input capture channel. To operate in this mode, the ABAUD bit (UxMODE<5>) should be set and the UxRX pin is internally connected to the input capture channel. The corresponding ICx pin is disconnected from the input capture channel.
The input capture channel used for auto baud support is device specific. E.g. for dsPIC30F4013 for auto baud support of the UART1 module, the input capture module IC1 is used, whereas for UART2 the input capture module IC2 is used.
This mode is only valid when the UART is enabled (UARTEN=1) and the loopback mode is disabled (LPBACK=0). Also, the user must program the capture module to detect the falling and rising edges of the START bit.