SCI recieve interrupt problem

bassplayer142 — Mon, 05 Apr 2010 23:19:52 GMT

I am currently using a minidragon board with a MC9S12DG256 chip (HCS12). I am trying to get an interrupt executed when some other unit sends anything through the serial port. I have set the interrupt to take what information was recieved and send it back but I get three outputs instead. Here the hex input is the 0x34 and the output is the following 6 hex numbers.

{34}

{E1}{01}{3E}

The Following is the code I used and is shortened for simplicity. Be aware that I have set up the clock and the baud rate to 9600 and they both work because without interrupts they work beautifully.

#include <hidef.h> /* common defines and macros */
#include <mc9s12dg256.h> /* derivative information */
#include <math.h>

#pragma LINK_INFO DERIVATIVE "mc9s12dg256b"

void interrupt 20 handler(){
perint();

}

void main(void) {
      clkinit();
      delay();
      initsciint();

EnableInterrupts;
while(1){}

}

void perint(void){

datain = inchar0();
outchar0(datain);
}

void initsciint(void){
    SCI0CR1 = 0x40; //setup sci port0 interrupts
    SCI0CR2 = 0x2C;
    SCI0BDH = 0x00;
    SCI0BDL = 0x9C;
}

void clkinit(void){ //set up eclock 24MHz

    SYNR = 0x02;
    REFDV = 0x01;
    CLKSEL = 0x00;
    PLLCTL = 0xF1;
    delay();
    CLKSEL = 0x80;
}

Thanks for any help!

Re: SCI recieve interrupt problem

itisravi — Thu, 29 Oct 2020 09:40:06 GMT

#pragma CODE_SEG __NEAR_SEG NON_BANKEDinterrupt 20 void SCI0_ISR(void){      /*i'm assuming that we are here due to RDRF.Check for other flags if you want to*/    (void)SCI0SR1;  //dummy read to clear interruput    if(index>24)index=0; //my static variable for buffer index    BufferRx[index++]=SCI0DRL;//copy byte    return;}#pragma CODE_SEG DEFAULT

This seems to work fine for me.May be you need to place the ISR in the non banked segment like i did. Also, try using pre define macros in your initsciint(). Makes it more readable. Example:

SCI0CR2 |= (SCI0CR2_TE_MASK | SCI0CR2_RE_MASK | SCI0CR2_RIE_MASK); /* Enable transmitter, Enable receiver, Enable receiver interrupt */

These macros can be found in the header file of your MCU derivative.

topic Re: SCI recieve interrupt problem in CodeWarrior for MCU

SCI recieve interrupt problem

Re: SCI recieve interrupt problem