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mesuty
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| RS422 comm slowing down the CPU |
 Posted: Thu Apr 21, 2005 1:11 am |
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Hi friends;
The code below is for a 30 node PIC18F452 connected to a PC via 4 wire RS422 system. System is working perfectly except.
1) When I set the adress , the CPU is getting correct address numbre. Say , If I give 0x01 as the node number , it is answering all the calls to node 0x01. But when I use the printf ("#%2X\r\n",RS485_ID) to read adress back , it is giving 0xD9 instead of 0x01.
2) After a couple of minutes of communication , total system is slowing down in communication, nearly 10-20 times.
Each message sent from PC contains @@nnCCPP+0x0d
where @@=header
nn : Node number
CC : Command
PP : Param value if needed.
CR (0x0d)
Do you think Should I rewrite the comms routines?.
Can somebody give me a ASCII charecter based example to broadcast just 5-6 bytes of data to subscribers of line.
Note. My compiler is PCWH 3.221
All ideas are wellcome.
| Code: |
#include <18F452.h>
#device adc=8
#use delay(clock=16000000)
#fuses NOWDT,WDT128,HS, PROTECT, NOOSCSEN, BROWNOUT, BORV20, NOPUT, STVREN, NODEBUG, NOLVP, NOWRT, NOWRTD, NOWRTB, NOWRTC, NOCPD, NOCPB, NOEBTR, NOEBTRB
#use rs232(baud=19200,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=9,ENABLE=PIN_C1,stream=PC)
#ZERO_RAM
int RS485_ID;
char inbuf[12]=" ";
byte gethex(char digit) {
if(digit<='9')
return(digit-'0');
else
return((toupper(digit)-'A')+10);
}
#int_RDA
RDA_isr()
{
int a,b;
gets(inbuf);
//output_high(PIN_C1);
//puts(inbuf);
if(inbuf[0]=='@' && inbuf[1]=='@') // @@ message header
{
if (inbuf[2]=='G' && inbuf[3]=='M') //GLOBAL SET metre sayac
{
metre_hedef=256*(inbuf[4])*16+gethex(inbuf[5]) + (inbuf[6])*16+gethex(inbuf[7]);
}
if (inbuf[2]=='G' && inbuf[3]=='R') //GLOBAL RUN
{
WM_RUN=1;
}
if (inbuf[2]=='G' && inbuf[3]=='S') //GLOBAL STOP
{
WM_RUN=0;
}
// Adres set procedure @@ AS NN ,(00..FF)
// During address set , node number not required.
if (inbuf[2]=='A' && inbuf[3]=='S')
{
RS485_ID=gethex((inbuf[4])*16+gethex(inbuf[5]));
write_eeprom (0,RS485_ID);
output_high(PIN_C1);
delay_ms(100); // EEpromda yazma tamamlanana dek bekle
printf ("#%2X\r\n",RS485_ID-208);
output_low(PIN_C1);
}
//If message blongs to this CPU
if (RS485_ID==gethex((inbuf[2])*16+gethex(inbuf[3])))
{ //output_high(PIN_C1);
switch (inbuf[4])
{
case 'M': { if (inbuf[5]=='S')//Metre counter value
{
metre_hedef=256*(inbuf[6])*16+gethex(inbuf[7]) + (inbuf[8])*16+gethex(inbuf[9]);
#IF (DEBUG==TRUE)
#ENDIF
}
Break;}
case 'W' : { if (inbuf[5]=='R')// Wax motor run
{
WM_RUN=1;
}
if (inbuf[5]=='S') // Wax motor Stop
{
WM_RUN=0;
}
}
Break;
case 'S' :{ if (inbuf[5]=='S') // Status send (inquiry)
{
}
printf("#%2X%c\r\n",RS485_ID-208,ST_stat); //Node status
Break;
}
}
}
}
//Clear comm buffer
for (a=0;a++;a<12) {
inbuf[a]=' ';
}
}
void INIT_MCU()
{
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_psp(PSP_DISABLED);
setup_spi(FALSE);
setup_wdt(WDT_OFF);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_16|RTCC_8_bit);
setup_timer_1(T1_INTERNAL|T1_DIV_BY_2);
setup_timer_2(T2_DISABLED,0,1);
setup_timer_3(T3_DISABLED|T3_DIV_BY_1);
RS485_ID=read_eeprom(0);
enable_interrupts(INT_TIMER1);
enable_interrupts(GLOBAL);
set_tris_a(0b00111111); // All in
set_tris_b(0b11001111);
set_tris_c(0b10110000);
set_tris_d(0b00000000);
set_tris_e(0b00000000);
}
void main()
{
INIT_MCU();
MPC_Reset();
init_vars();
enable_interrupts(INT_RDA); // open serial port
ST_stat='R'; // Status :=AFTER_RESET
While(1)
{
//Normal tasks
}
} |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Thu Apr 21, 2005 6:23 am |
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See this line
| Code: | enable_interrupts(INT_TIMER1);
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I don't see an interrupt handler for it. This will cause your program to constantly run the interrupt handler and run dog slow. |
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TSchultz
Joined: 08 Sep 2003
Posts: 66
Location: Toronto, Canada
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| Posted: Thu Apr 21, 2005 6:52 am |
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You really need to reduce the code in your serial interrupt handler. You should just receive, maybe validate, the packet, then once you have the full packet set a flag so a handler in the main loop can decode and process the packet.
Here is the code I run for RS485, it is a custom prototocol but should be easy to follow. The code has been fairly well optimized (I think).
| Code: | /****************************************************************************
Interrupt routine to receive data using internal USART.
Routine handles all aspects of packet collection and validation.
NewData is set when a complete and valid packet has been received if;
- BOF must be valid
- ID must be ours, or global id
- number of bytes must match LEN field
- FCS must be valid, will be zero if correct
- EOF must be found after FCS character
- all bytes must be received within allowed timeframe (see timer ISR routine)
*****************************************************************************/
#INT_RDA
void isr_RXSerial( void ) {
static byte FCS, c;
if( kbhit() ) { //test to make sure byte is in buffer, ISR may have been called erroneously
c = getc(); //get byte from buffer
if ( !serialA_Working ) { //Are we already getting a packet?
serialA_Working = ( c == BOF ); //if BOF then we are getting a packet
serialA_Timeout = false; //clear timeout
serialA_Bytes = 0; //we have no data bytes yet
serialA_GoodData = 0;
PacketErr++; //Assume packet is bad until verified
} else {
serialA.Buffer[serialA_Bytes] = c; //put character in buffer
serialA_Working = ( serialA_Bytes++ < SERIAL_BUFFER_SIZE ); //don't exceed buffer size
if (serialA_Bytes == 1) {
serialA_Working = ( ClientID == c ) || ( GlobalID == c ); // If ID no good then discard remaining chars
serialA_Reply = ( ClientID == c ); // Allow reply if ID is ClientID, don't reply if GlobalID
FCS = c; //set FSC with first byte
} else if ( serialA_Bytes <= serialA.Data.LEN + 1 ) {
FCS ^= c; //Still getting data bytes so accumulate FSC
} else if ( c == EOF ) { //Check EOF
if( FCS == 0 ){
PacketErr--; //FSC is valid so packet is not in error
serialA_GoodData = 1;
}
serialA_NewData = 1; //( FCS == 0 ); //If FSC is good then we have good packet
serialA_Working = false; //We are no longer getting data
PacketsRX++; //Increment good packet count
} else {
serialA_Working = false; // data receive error so stop grabbing data
}
}
}
}
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In my main loop I then check for serialA_NewData, it true then I have a good packet to work with. The only other thing not in the code above is a timeout which is handled in a timer irq, it just clears SerialA_Working which aborts the current RX.
Hope this helps some. |
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