Reset UART (restart UART)

Reset UART has two methods:

1. UART reset. Write 0 to the UART reset bit (urst) of the power and emulation control register, urpecr. This operation resets the UART state machine without affecting the UART registers.
2. DSP reset. Reduce the reset # pin of the DSP. The entire DSP will reset and remain in the reset State until the reset # pin is increased. As part of the DSP, The UART state machine will also reset and the UART register will be restored to the default initial state.

The default values of UART registers and TX signals are as follows:

Note:

1. The frequency-division lock registers (DLM and DLL) of UART will not be affected in the hardware reset and UART software reset. They must be reloaded after power-on. Before starting the serial communication, make sure that the correct sub-frequency and stored in the two sub-frequency lock registers (to provide the required baud rate ).
2. For UART operation, the 16-bit divisor must be greater than 0, that is, the value in the frequency lock register (urdlm and urdll) must be greater than 0.
3. To ensure proper communication between the uart and the dma controller, the DMA mode (dmamod) Bit Of The urfcr register must be 1. The DMA mode (dmamod) Bit must always be 1. After the hardware is restarted, rewrite the DMA mode (dmamod) bit from 0 to 1.