Serial Port Complete - Latest Microcontroller projects

Ports for Embedded Systems

 An hserin statement can read a byte at the serial port:

serial_in var byte

if (PIR1.5 = 1) then

' A byte is available. Read it.

hserin [serial_in]

endif

Instead of checking RCIF before calling hserin, a statement can call hserin with

a timeout that jumps to a label if a byte doesn’t arrive. Reading RCIF is more

efficient because the code doesn’t waste time waiting, but a timeout can be use-

ful if the application is expecting data and has no other urgent tasks.

serial_in var byte

timeout var word

timeout = 1000

' Wait for a byte on the serial port.

hserin timeout, give_up, [serial_in]

' A byte was received. Do something with it.

' Jump here if hserin times out.

give_up:

 The DataRdyUSART function returns 1 when RCIF =1. The getcUSART
function reads a byte from the port. The ReadUSART function is identical to
getcUSART.
unsigned char serial_in;

if DataRdyUSART()

{

// A byte is available.

serial_in = getcUSART();

}