1.1 Advantages of UART with Protocol Support

The new UART with protocol support module is helpful in many ways for handling the flow of data for the specific protocols. Figure 1-2 is a timing diagram for a DMX message. The individual events have specific timing requirements as defined in the DMX specifications. The UART module with protocol support will automatically produce the correct sequence of events with the timing requirements. The user software does not have to account for maintaining the timings for these events.

When used as a DMX receiver, the module can detect a break condition and determine if it is valid, and then start receiving the DMX packets. It will ignore the DMX packet if the break event timings are not met. Also, as a DMX receiver only a few bytes in the stream of 512 data bytes might be significant. The UART module can be configured to receive a subset of the full DMX message and will only produce receive interrupts when the necessary bytes are received. This eliminates the need for the software to handle unnecessary interrupts and keep track of the number of bytes received.

Several of the newer 8-bit PIC microcontrollers feature the DMA module, which can be used in conjunction with the UART to transmit or receive data independently of the CPU. This frees up the CPU to handle other important tasks while the DMA handles the DMX data packet.