ABL electronic PIC Microcontrollers PIC16 - Manual (Page 255)

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mikroC - C Compiler for Microchip PIC microcontrollers
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Library Example
The example demonstrates working with PIC as Slave nod in RS-485 communication. PIC
receives only packets addressed to it (address 160 in our example), and general messsages with
target address 50. The received data is forwarded to PORTB, and sent back to Master.
unsigned short dat[8]; // buffer for receiving/sending messages
char i = 0, j = 0;
void interrupt() {
/* Every byte is received by RS485Slave_Read(dat);
If message is received without errors,
data[4] is set to 255 */
if (RCSTA.OERR) PORTD = 0x81;
RS485Slave_Read(dat);
} //~
void main() {
TRISB = 0;
TRISD = 0;
Usart_Init(9600); // Initialize usart module
RS485Slave_Init(160); // Initialize MCU as Slave with address 160
PIE1.RCIE = 1; // Enable interrupt
INTCON.PEIE = 1; // on byte received
PIE2.TXIE = 0; // via USART (RS485)
INTCON.GIE = 1;
PORTB = 0;
PORTD = 0;
dat[4] = 0; // Ensure that msg received flag is 0
dat[5] = 0; // Ensure that error flag is 0
do {
if (dat[5]) PORTD = 0xAA; // If there is error, set PORTD to $AA
if (dat[4]) { // If message received:
dat[4] = 0; // Clear message received flag
j = dat[3]; // Number of data bytes received
for (i = 1; i < j; i++)
PORTB = dat[--i]; // Output received data bytes
dat[0]++; // Increment received dat[0]
RS485Slave_Write(dat, 1); // Send it back to Master
}
} while (1);
} //~!