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USART address detect

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funmix

Joined: 27 Mar 2007
Posts: 33

USART address detect

Posted: Wed Apr 25, 2007 10:33 am

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Any comment for the code? I am going to implement 9 bit addressable mode USART.

Code:

#case
#include <18F4520.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP

#define FREQ_OSC 20000000
#define BAUD_RATE 19200
#use delay(clock = FREQ_OSC)
#use rs232(baud=19200,xmit=PIN_C6,rcv=PIN_C7,ENABLE=PIN_C5,bits=8,parity=N)

#define RS485_ENABLE PIN_C5
#byte SPBRG = 0xFAF
#byte PIR1 = 0xF9E
#byte RCSTA = 0xFAB
#byte TXREG = 0xFAD
#byte RCREG = 0xFAE
#byte TXSTA = 0xFAC

#bit TXIF = PIR1.4
#bit RCIF = PIR1.5

#bit CSRC = TXSTA.7
#bit TX9 = TXSTA.6
#bit TXEN = TXSTA.5
#bit SYNC = TXSTA.4
#bit BRGH = TXSTA.2
#bit TRMT = TXSTA.1
#bit TX9D = TXSTA.0

#bit SPEN = RCSTA.7
#bit RX9 = RCSTA.6
#bit SREN = RCSTA.5
#bit CREN = RCSTA.4
#bit ADDEN = RCSTA.3
#bit FERR = RCSTA.2
#bit OERR = RCSTA.1
#bit RX9D = RCSTA.0

int8 g_packet[40];
#define BUFFER_LEN 32
char recchar = 0;
char txvchar = 0;

#int_rda
void rda_isr()
{
recchar = RCREG;
if(OERR)
{
CREN = 0;
#asm
nop
#endasm
CREN = 1;
}
}

void my_send(char cmd)
{
while(!TXIF);
TXREG = cmd;
}

char my_receive(void)
{
int temp;
int retval;

while(!RCIF);
temp = RCSTA;
retval = RCREG;
if(bit_test(temp,1))
{
CREN = 0;
CREN = 1;
}
return(retval);
}

void init_uart(void)
{

SPBRG = (FREQ_OSC/(BAUD_RATE*16))-1;
TXSTA = 0x66;//0x26
RCSTA = 0xD8;//0x90
}

void SendPacket(void)
{

int16 hdr;
char cs = 0;
char i;

output_high(RS485_ENABLE);
TX9 = 1;
TX9D = 1;

hdr = 0x100 +g_packet[0];
putc(hdr);

TX9 = 0;
TX9D = 0;

for(i=1;i<BUFFER_LEN;i ++)
{
cs+=g_packet[i];
putc(g_packet[i]);
}

putc(cs);

output_low(RS485_ENABLE);
}

void main()
{

char cmd;

enable_interrupts(INT_RDA);
enable_interrupts(GLOBAL);

init_uart();

printf(my_send,"Sending out\n\r");

SendPacket()

/* while(1)
{

cmd = my_receive();
my_send(cmd);
}*/
}

funmix

Joined: 27 Mar 2007
Posts: 33

Posted: Thu Apr 26, 2007 2:05 am

Reply with quote

I have modifed the code..

below is the #int_rda routine, please comment

Code:

#include <18F4520.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP

#define FREQ_OSC 20000000
#define BAUD_RATE 19200
#use delay(clock = FREQ_OSC)
#use rs232(baud=19200,xmit=PIN_C6,rcv=PIN_C7,ENABLE=PIN_C5,bits=8)

#int_rda
void serial_isr()
{
int t;
char temp;
ADDEN = 1;
temp = RCREG;
if(ninth_bit)
{
if(temp == Node_Address)
{
ADDEN = 0;
receive_data()
}
}
}

kevcon

Joined: 21 Feb 2007
Posts: 142
Location: Michigan, USA

Posted: Thu Apr 26, 2007 6:50 am

Reply with quote

I think you neeed to start over, you are missing a few things and you have stuff you don't need.

You need a line as shown below for the compiler to setup the uart correctly.

Code:

#use delay( clock = 20,000,000 )

If you are using 9 bits you neet to set the uart correctly.

Code:

#use rs232 baud=19200,xmit=PIN_C6,rcv=PIN_C7,ENABLE=PIN_C5,bits=9)

You are duplicating things that are built in to the compiler.
This is taken care of by the #use rs232 line

Code:

void init_uart(void)
{

SPBRG = (FREQ_OSC/(BAUD_RATE*16))-1;
TXSTA = 0x66;//0x26
RCSTA = 0xD8;//0x90
}

look at the CCS serial examples.

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