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#include "mbed.h"
volatile unsigned int ticks = 0;
DigitalOut led(LED_BLUE);
extern "C" void lptmr_isr(void) {
// write 1 to TCF to clear the LPT timer compare flag
LPTMR0->CSR |= LPTMR_CSR_TCF_MASK;
ticks++;
}
int main() {
/* Clock the timer */
SIM->SCGC5 |= SIM_SCGC5_LPTMR_MASK;
/* Reset */
LPTMR0->CSR = 0;
/* Compare value */
LPTMR0->CMR = 1000;
/* Enable interrupt */
LPTMR0->CSR |= LPTMR_CSR_TIE_MASK;
/* Set interrupt handler */
NVIC_SetVector(LPTimer_IRQn, (uint32_t)lptmr_isr);
NVIC_EnableIRQ(LPTimer_IRQn);
/* select LPO for RTC and LPTMR */
LPTMR0->PSR = LPTMR_PSR_PCS(3); // ERCLK32K -> 8MHz
LPTMR0->PSR |= LPTMR_PSR_PRESCALE(2); // divide by 8
/* Start the timer */
LPTMR0->CSR |= LPTMR_CSR_TEN_MASK;
led = 0;
while (true) {
wait(1);
led = 1;
printf("%d\n", ticks);
wait(1);
led = 0;
printf("%d\n", ticks);
}
}
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