rs232 odd length strings

[delene]

I am using ISR to receive data in through the rs232 port. My problem is that the strings that i am receiving are NOT fixed length. Some are 8 characters and others 11. there is no start of message, or end of message. Any suggestions on how I capture the full string

Thanks
Delene
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This message was ported from CCS's old forum
Original Post ID: 144516311

[Neutone]

<font face="Courier New" size=-1>:=I am using ISR to receive data in through the rs232 port. My problem is that the strings that i am receiving are NOT fixed length. Some are 8 characters and others 11. there is no start of message, or end of message. Any suggestions on how I capture the full string
#int_TIMER1 //*********************************
TIMER1_isr() // 1.5 byte periods after last byte
{ disable_interrupts(int_TIMER1); // TMR1 Overflow Interrupt Enable bit off
--PacketIndex; // Set index to last recieved byte
CommPacketIn=1; // Tag packet for processing
}
#int_RDA //**************
RDA_isr() // BYTE RECIEVED
{ int8 x; // Create byte storage
x = fgetC( chanA ); // Get incomming byte from buffer
if(!CommPacketIn) // Do not accept incomming bytes if packet is waiting
{ PacketBuffer[PacketIndex++] = x; // Place incomming byte in PacketBuffer
if( bit_test(PacketIndex,6)) // If packet index larger than packetbuffer (64)
PacketIndex = 0; // Zero packet index value
set_timer1( 48640 ); // Wait 1.5 byte periods then interupt (set for 4800bps now) EVALUATE FOR PERFORMANCE
TMR1IF=0; // Clear timer1 overflow Interrupt Flag bit
enable_interrupts(int_TIMER1); // TMR1 Overflow Interrupt Enable bit on
}
}
</font>
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This message was ported from CCS's old forum
Original Post ID: 144516312

[Levett Prins]

:=I am using ISR to receive data in through the rs232 port. My problem is that the strings that i am receiving are NOT fixed length. Some are 8 characters and others 11. there is no start of message, or end of message. Any suggestions on how I capture the full string
:=
:=Thanks
:=Delene

The most succesful method I used so far is to simply wait for a timeout condition and then to process the RX buffer. I am using it to read variable length strings from a modem. Change the timeout length according to the baud rate you are using.

Good luck

Levett


#INT_RDA
void RDA_isr()
{
long timeout=0;
char c;

c=fgetc(MODEM); RXbuffer[RXi]=c;

while(!kbhit() && (++timeout<5000)) // wag vir volgende karakter
{delay_us(10); if(kbhit()) break;} // 19200BPS = 2ms / CHAR (50000 = 500 ms)

if(timeout>=5000) //end of response
{
RXi_END=RXi; //end of line index
//**PROCESS RXbuffer HERE!!!
RXi=RXbuffer_LEN_LOD; //cause overflow to clear and reset RXbuffer
}
RXi++;
if(RXi>=64) //prevent overflow
{
for(RXi=0; RXi RXi=0;
}
}
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This message was ported from CCS's old forum
Original Post ID: 144516385