rs232 problems

[Iulian Demetrescu]

hi to all.
i have a very big problem. i try to use the hardware uart of an 16f877 at 115200 baud. I created the receive and send functions for the uart but after two packets succesfuly received the entire system locks up and i do not know what to do. The ASM counterpart of tis application works fine.
i post below the code.

#include <16F877.h>
#device PIC16F877 *=16 ADC=10
#fuses HS,NOWDT,NOPROTECT,PUT,BROWNOUT,NOLVP,NOCPD,WRT
#zero_ram
#use delay(clock=20000000)

//general var and const definitions


#define BUF_SIZE 96
#define LCP 0xC021 //lcp packet
#define IP 0x0021 //ip packet
#define IPCP 0x8021 //ipcp config packet
#define CCP 0x80FD //compression
#define CHAP 0xC223 //chap authentication
short lcp_up; //lcp negotiated successfuly
short ip_up; //ipcp negotiated succesfuly
short frm_avail;//frame available for decoding
short adcmp; //address and ctl field compression
short err_out; //error out sys
long curfcs; //frame check sequence
int buf_pos; //receive buffer position





//sw uart
#use RS232(BAUD=9600,XMIT=PIN_B1,RCV=PIN_B0)


void put_to_a( char c){
putc(c);
}

char get_from_a ( ) {
return(getc());
}
//hw uart
#use RS232(BAUD=115200,XMIT=PIN_C6,RCV=PIN_C7)

void put_to_b( char b) {
putc(b);
}

char get_from_b ( ) {
return(getc());
}


//clear bank 2 ram buffer
void clr_pos_buf(){
int ilp = 0;
while (ilp <= BUF_SIZE) {
write_bank(1,ilp++,0x00);
}
}

//init and setup modem
void init_zapp_mdm(){
char m;
put_to_b("AT&FV0E0\r"); //say reset to modem
put_to_b("ATV0E0+CRM=1\r"); //init string to modem
//m = get_from_b(); //wait for something from modem
//switch(m){
//case '0' : put_to_a("ok\n\r");break;
//case '4' : put_to_a("error\n\r"); break;
//}
}

void dial_zapp_mdm(){
put_to_b("ATDT#777\r");
}


//signalling states


//routine tested and working
//checksum calculator part 1
long calc(long cs) {
int i; //loop variable
cs&=0xFF;
for (i=0;i<8;i++){
if (cs&1) {
cs /= 2;
cs ^=0x8408;
} else {
cs /=2;
}
}
return cs;
}
//routine tested and working
//checksum calculator part 2
void valid_fcs(){
int l;
char z;
//we should init the fcs engine
for (l=0;l z=read_bank(1,l); //read data from meory
curfcs=calc(z^curfcs)^(curfcs/256);
}
if (curfcs==0xF0B8) {
put_to_a("o");
} else {
put_to_a("w");
}
}




void init_ppp_engine(){
lcp_up = 0;
ip_up = 0;
adcmp=0;
err_out=0; //no exit
//lcp_off();
//ip_off();
curfcs = 0xFFFF;//init fcs value to default
}



//routine tested and running at 17.04.2002
void rcv_packet(){ //main packet receiver routine
char c; //data holder
short in_packet=0;//in frame indicator
short escc=0; //escape char sequence
buf_pos=0;
do { //we stay in this until something arrives and check for conformity
c = get_from_b();//read from port
if (c==0x7E){
in_packet = 1;//we succesfuly received start frame sequence
}
}while(!in_packet);
do {//we stay in here until we reach end of packet
c=get_from_b(); //read from port
if (!lcp_up){
switch(c){
case 0x7E:in_packet=0;break;
case 0x7D:escc=1;break;
default :if (!escc) {write_bank(1,buf_pos++,c);} else {
c^=0x20;
escc=0;
write_bank(1,buf_pos++,c);}
}

}
else {
if(c==0x7E){in_packet=0;} else {write_bank(1,buf_pos++,c);}

}
}while(in_packet);
//when we reach this stage we have a ppp packet decoded in memory

}

void snd_packet(int osz){ //send packet routine
int slp; //send loop char
char z; //mini buffer
curfcs=0xFFFF;//reset fcs
put_to_b(0x7E);//frame start
for (slp=0;slp z=read_bank(1,slp); //read char in buffer
curfcs=calc(z^curfcs)^(curfcs/256); //calculate fcs value
if (z<0x20) {
z ^= 0x20;
put_to_b(0x7D); //send escape sequence
put_to_b(z); //send char
} else {
put_to_b(z);
}
}
curfcs =~curfcs; //ones complement
put_to_b(curfcs&255);
put_to_b(curfcs/256);
put_to_b(0x7E);
}

void decode_packet(){ //main ppp packet decoder
long p_type; //packet type as read from buffer
int offset=0; //offset in packet
char r; //request type

if (!adcmp) {offset=2;}//we don't have address and field compression
p_type=read_bank(1,offset) * 256 + read_bank(1,offset+1);//protocol type
if (p_type == LCP) {

r=read_bank(1,offset+2);//read request type
if (r==0x01) { //we have a request
write_bank(1,offset+2,0x02); //we make it ack
snd_packet(buf_pos - 2); //send the packet minus old fcs
//now we send the request
put_to_b(0x7e);
put_to_b(0xff);
put_to_b(0x7d);
put_to_b(0x23);
put_to_b(0xc0);
put_to_b(0x21);
put_to_b(0x7d);
put_to_b(0x21);
put_to_b(0x7d);
put_to_b(0x22);
put_to_b(0x7d);
put_to_b(0x20);
put_to_b(0x7d);
put_to_b(0x34);
put_to_b(0x7d);
put_to_b(0x22);
put_to_b(0x7d);
put_to_b(0x26);
put_to_b(0x7d);
put_to_b(0x20);
put_to_b(0x7d);
put_to_b(0x20);
put_to_b(0x7d);
put_to_b(0x20);
put_to_b(0x7d);
put_to_b(0x20);
put_to_b(0x7d);
put_to_b(0x25);
put_to_b(0x7d);
put_to_b(0x26);
put_to_b(0xfa);
put_to_b(0x33);
put_to_b(0xa0);
put_to_b(0x7d);
put_to_b(0x32);
put_to_b(0x7d);
put_to_b(0x27);
put_to_b(0x7d);
put_to_b(0x22);
put_to_b(0x7d);
put_to_b(0x28);
put_to_b(0x7d);
put_to_b(0x22);
put_to_b(0x83);
put_to_b(0x95);
put_to_b(0x7e);
}
if (r==0x02){
adcmp=1; //addres and field compression
lcp_up=1; //lcp negotiated

}

if (r==0x09){ //we have an echo request
//put_to_a("E");
write_bank(1,offset+2,0x0A); //we make it echo reply
snd_packet(buf_pos - 2); //send the packet minus old fcs
}


}//end lcp processing
if (p_type == CHAP) {
put_to_a("C");//say chap

}//end chap processing
}




main() {
char s;
put_to_a("Online\n\r");
init_zapp_mdm(); //set modem
dial_zapp_mdm();//dial to zapp host
init_ppp_engine();
while(!err_out) {
clr_pos_buf();
rcv_packet();
decode_packet();
}
put_to_a("end");

}
___________________________
This message was ported from CCS's old forum
Original Post ID: 3862

[PCM programmer]

:= but after two packets succesfuly received the entire system locks up and i do not know what to do.
:=
:=#use RS232(BAUD=115200,XMIT=PIN_C6,RCV=PIN_C7)
----------------------------------------------------

I didn't review your code in detail, but I have this advice:

You can check to see if the hardware USART is locking up by
adding the ERRORS directive. Example:

#use RS232(BAUD=115200,XMIT=PIN_C6,RCV=PIN_C7, ERRORS)

This will clear any over-run or framing errors that occur.
You'll still lose the character, but at least it won't lock up.
___________________________
This message was ported from CCS's old forum
Original Post ID: 3863

[Iulian Demetrescu]

Thank you very much. my code is now running ok. i spent an entire night debugging and changing things.CCS is really great.What i did in assembly in many hours and days i did in c in about 5 hours. Thank you CCS.


:=:= but after two packets succesfuly received the entire system locks up and i do not know what to do.
:=:=
:=:=#use RS232(BAUD=115200,XMIT=PIN_C6,RCV=PIN_C7)
:=----------------------------------------------------
:=
:=I didn't review your code in detail, but I have this advice:
:=
:=You can check to see if the hardware USART is locking up by
:=adding the ERRORS directive. Example:
:=
:=#use RS232(BAUD=115200,XMIT=PIN_C6,RCV=PIN_C7, ERRORS)
:=
:=This will clear any over-run or framing errors that occur.
:=You'll still lose the character, but at least it won't lock up.
___________________________
This message was ported from CCS's old forum
Original Post ID: 3869