Here, X is the contents of the register SPBRG. The formula used to compute for the baud rate is different in high speed or low speed mode: Four our purpose, we will only look at four bits from TXSTA and 1 bit on RCSTA.īit TXEN (bit 5) on TXSTA enables or disables transmission, SYNC ( bit 4) sets asynchronous or synchronous mode while BRGH (bit 2) sets high speed or low speed mode. The TXSTA and RCSTA registers are shown below: The SPBRG is used to calculate the baud rate of the transmissions. To configure the PIC’s hardware USART, we need three registers: TXSTA, RCSTA and SPBRG. For this tutorial, we’ll be using the PIC16F877A. In contrast, hardware USART exclusively uses the pins RC6 (TX) and RC7 (RX).īut hardware serial is not found on all PICs - the PIC16F84A doesn’t have one. This is useful when you ran out of pins and need to communicate to multiple devices. Software serial offers the advantage of assigning transmit and receive pins it to any output pin. While you can implement serial communications through “bit-banging”, i.e., setting a pin high or low in specific time intervals (also known as software serial), using the hardware USART module is a much more reliable and easier approach.
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