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LPC2129 UART ISR Problem

Garrett Young

I'm using the LPC2129 and Keil Tools. The purpose of the code is to interrupt on the receipt of a single byte of data and assign "data" to its value. The interrupt seems to work however "data" isn't the right value. Please help, Thanks.

#include <stdio.h> /* prototype declarations for I/O functions */
#include <lpc21xx.h> /* LPC21xx definitions */

void U1ISR(void) __irq; //Declare UART1 IRQ ISR

int data;

int main (void) {

PINSEL0 = 0x0005800A; // Enable UART1

U1LCR = 0x83; /* 8 bits, no Parity, 1 Stop bit */
U1DLL = 8; /* 115200 Baud Rate @ 15MHz VPB Clock */
U1LCR = 0x03; /* DLAB = 0 */
U1IER = 0x1; //Enable the RDA interrupt

VICVectAddr0 = (unsigned long)U1ISR; //Set UART1 ISR Vector Address
VICVectCntl0 = 0x20 | 7; //Enable Slot, Set Channel 7
VICIntEnable = 0x80; //Enable Int UART1

blah ... blah ... blah

while (1) {

yada ... yada ... yada

}

}

void U1ISR(void) __irq {

U1IIR |= 0x01; /* Clear Interrupt */

data = U1RBR;

VICVectAddr = 0x0; /* return from interrupt */

}

Parents
  • 0 in reply to Garrett Young

    Thanks, so you confirm that your small code piece can be switched between ARM and Thumb mode using the Flash-Configure, Flash Tools-C tab,-Use Thumb Mode toggle and it compiles in both modes without problems. Is so, I will try a clean install.

    I was wondering about your code, initially at (*1*)VicVectAddr0 gets U1ISR, which makes sense. Then at the end of the interupt (*2*) it gets put back to 0x0. and back to U1ISR addr at (*1*) again. Is this the right thing to do I wonder. I would have thought that the ISR vector can be left alone and something else done to reset the interupt for next time. Am I completely wrong or just not understanding what is happening?

    (*1*) VICVectAddr0 = (unsigned long)U1ISR; //Set UART1 ISR Vector Address
    VICVectCntl0 = 0x20 | 7; //Enable Slot, Set Channel 7
    VICIntEnable = 0x80; //Enable Int UART1

    void U1ISR(void) __irq {
    U1IIR |= 0x01; /* Clear Interrupt */
    data = U1RBR;
    (*2*) VICVectAddr = 0x0; /* return from interrupt */

Reply
  • 0 in reply to Garrett Young

    Thanks, so you confirm that your small code piece can be switched between ARM and Thumb mode using the Flash-Configure, Flash Tools-C tab,-Use Thumb Mode toggle and it compiles in both modes without problems. Is so, I will try a clean install.

    I was wondering about your code, initially at (*1*)VicVectAddr0 gets U1ISR, which makes sense. Then at the end of the interupt (*2*) it gets put back to 0x0. and back to U1ISR addr at (*1*) again. Is this the right thing to do I wonder. I would have thought that the ISR vector can be left alone and something else done to reset the interupt for next time. Am I completely wrong or just not understanding what is happening?

    (*1*) VICVectAddr0 = (unsigned long)U1ISR; //Set UART1 ISR Vector Address
    VICVectCntl0 = 0x20 | 7; //Enable Slot, Set Channel 7
    VICIntEnable = 0x80; //Enable Int UART1

    void U1ISR(void) __irq {
    U1IIR |= 0x01; /* Clear Interrupt */
    data = U1RBR;
    (*2*) VICVectAddr = 0x0; /* return from interrupt */

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