Serial Port Complete - Latest Microcontroller projects

Ports for Embedded Systems

Using a 16-bit value to set the baud rate requires setting BRG16 = 1 and storing

a value in SPBRGH. This example sets a bit rate of 2400 bps assuming FOSC =

4 MHz:

BAUDCONbits.BRG16 = 1;

SPBRGH = 1;

OpenUSART (USART_TX_INT_OFF &

USART_RX_INT_OFF &

USART_ASYNCH_MODE &

USART_EIGHT_BIT &

USART_CONT_RX &

USART_BRGH_HIGH,

0x9f);

! 
$

Firmware can write individual bytes or arrays of bytes to a port. Before writing

to a port, firmware should wait for TXIF = 0, indicating that the port isn’t busy

sending a byte.

 The hserout statement waits for TXIF = 0 and writes data to the port.

Each of the hserout statements below write the same value (41h, the code for

the character “A”) to the port:

hserout ["A"]

hserout [$41]

test var byte

test = $41

hserout[test]

An hserout statement can also write multiple bytes to a port. This statement

writes a string:

hserout [“hello, world"]

This statement writes the values stored in a byte array:

test var byte[2]

test[0] = "O"

test[1] = "K"

hserout[STR test]