Content originally posted in LPCWare by Shoaib on Sat Aug 16 01:25:27 MST 2014
Hi everyone!
I am working on the QEI of LPC1769 but was facing few issues with the interrupt status register. I want to measure the velocity of the motor whenever the LPC_QEI->QEITIME register overflows.
The problem is that the timer interrupt in the LPC_QEI->QEIINTSTAT becomes high even though the timer has not overflowed. It does it even clear the interrupt when the LPC_QEI->QEICLR is used.
/**** code****/
#ifdef __USE_CMSIS
#include "LPC17xx.h"
#endif
#include <cr_section_macros.h>
uint32_t meas_rpm,i=0,j=0,k=0,test=0,test1=0,test2=0,ans;
void qei_init()
{
LPC_SC->PCONP |= 1<<18; // Power up QEI
LPC_SC->PCLKSEL1 |= 3; // Select clock for QEI = cclk/8
LPC_PINCON->PINSEL3 |= (1<<8); // configure as MCI0-QEA - P1.20
LPC_PINCON->PINSEL3 |= (1<<14); // configure as MCI1-QEB - P1.23
LPC_PINCON->PINSEL3 |= (1<<16); // configure as MCI2-INDX - P1.24
LPC_QEI->QEICONF |= (1<<2); // Set quadrature mode - 4x mode
LPC_QEI->QEIMAXPOS= 0xFFFFFFFF; // Maximum pulse count limit after which counter resets
LPC_QEI->FILTER = 0; // Number of clk delays
}
void en_encoderint() [color=#c0f]//Done in two ways[/color]
{
//LPC_QEI->QEIIES |= (1<<5);
//LPC_QEI->QEIIES &= 0xFFFFE002 ;[color=#c0f]1) Used only this line[/color]
LPC_QEI->QEIIES |= (1<<5); [color=#c0f]2) Used this and the following line[/color]
LPC_QEI->QEIIES |= (1<<1);
}
void QEI_IRQHandler()
{
k=k+1;
}
void main(void) {
qei_init();
en_encoderint();
LPC_QEI->QEICLR &=0x00001FFF;[color=#c0f]//INTSTAT = 0x120, expected value = 0 as all bits cleared[/color]
LPC_QEI->QEILOAD = 10000;[color=#c0f]// Has no effect with a smaller value (eg 10)[/color]
while(1) {
ans=LPC_QEI->QEIINTSTAT & 2;
if(ans == 2) [color=#c0f] //the statement if(LPC_QEI->QEIINTSTAT & 2 == 2) is giving incorrect solution (res=1?)[/color]
{
LPC_QEI->QEICLR &= 0x00001FFF;[color=#c0f]// is not affecting the INTSTAT reg[/color]
meas_rpm = (SystemCoreClock/8)*LPC_QEI->QEICAP*60/(LPC_QEI->QEILOAD*1024*4);
[color=#c0f]// I want to clear the interrupt so that I measure the velocity at the exact instant when the velocity timer reg overflows[/color]
}
}
}
/**** End of code****/
The second problem I am facing is that the code never enters the QEI ISR. I used a test int k to see if ISR code was implemented but it did not change.
Thanks,
