Tool/software: TI C/C++ Compiler
I am using a timer to generate a pulse with different periods. The timer is working fine when counting from 80 to 16M counts (TIMER0->TAILR). But when I go below 80, it always give the same period (1.7 usec).
Here is my code:
#include <lm4f120h5qr.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
void TIMER_INIT(){
SYSCTL->RCGCTIMER |= (1<<0);
//1: Disable the timer (clear the TnEN bit in the GPTMCTL register)
TIMER0->CTL &= ~(1<<0);
//2: Write the GPTMCFG with a value of 0x00000000
TIMER0->CFG = 0x00000000;
//3: Configure the TnMR field in the GPTMTnMR. 0x2 for Periodic
TIMER0->TAMR |= (0x2<<0);
//4:Count up timer
TIMER0->TAMR &= (1<<4);
//5: Load the value that you will count down/up to
TIMER0->TAILR = 16000000; //0x00F42400 16,000,000 this corresponds to the clk speed of this microcontroller
//6: If interrupts are required, set the appropriate bits in the GPTMIMR
//7: Set the TnEN bit in the GPTMCTL register to enable the timer and start counting
TIMER0->CTL |= (1<<0);
}
int main()
{
TIMER_INIT();
while (1){
while((TIMER0->RIS & 0x00000001) != 1){} // Wait if TIMER0 has not timed out.
TIMER0->ICR |= (1<<0);
GPIOC->DATA ^= (1<<5); //trigger C5
}
}
Note: I am using a logic analyzer to measure the pulse period.
