pwm.c

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#include "pwm.h"

int mem_fd;
volatile uint16_t* pwmss0_regs;
volatile uint16_t* pwmss1_regs;

int pwm_setup(void) {

    // open /dev/mem for memory mapping
    if ((mem_fd = open("/dev/mem", O_RDWR | O_SYNC)) < 0) {
        rl_log(ERROR, "can't open /dev/mem");
        return FAILURE;
    }

    // map pwm0 registers into virtual memory
    pwmss0_regs =
        (volatile uint16_t*)mmap(NULL, PWM_SIZE, PROT_READ | PROT_WRITE,
                                 MAP_SHARED, mem_fd, PWMSS0_BASE);
    if (pwmss1_regs == (volatile uint16_t*)MAP_FAILED) {
        rl_log(ERROR, "mmap failed");
        close(mem_fd);
        return FAILURE;
    }

    // map pwm1 registers into virtual memory
    pwmss1_regs =
        (volatile uint16_t*)mmap(NULL, PWM_SIZE, PROT_READ | PROT_WRITE,
                                 MAP_SHARED, mem_fd, PWMSS1_BASE);
    if (pwmss1_regs == (volatile uint16_t*)MAP_FAILED) {
        rl_log(ERROR, "mmap failed");
        close(mem_fd);
        return FAILURE;
    }

    return SUCCESS;
}

void pwm_close(void) {

    // unmap memory
    munmap((void*)pwmss0_regs, PWM_SIZE);
    munmap((void*)pwmss1_regs, PWM_SIZE);

    // close /dev/mem
    close(mem_fd);
}

void pwm_setup_range_clock(int sample_rate) {

    int period = PWM_PERIOD_SCALE / sample_rate;

    // setup ehrpwm
    pwmss1_regs[TBCTL] =
        TBCTL_DEFAULT | UP_DOWN_COUNT | PRESCALE2; // set clock mode

    pwmss1_regs[TBPRD] = period; // set clock period

    pwmss1_regs[CMPA] = (1 - PULSE_WIDTH / 2) *
                        period; // set compare registers for both output signals
    pwmss1_regs[CMPB] = PULSE_WIDTH / 2 * period;

    pwmss1_regs[AQCTLA] = RWC_AQ_A; // set actions
    pwmss1_regs[AQCTLB] = RWC_AQ_B;
}

void pwm_setup_adc_clock(void) {

    // setup ehrpwm
    pwmss0_regs[TBCTL] = TBCTL_DEFAULT;
    pwmss0_regs[TBPRD] = ADC_CLOCK_PERIOD;
    pwmss0_regs[CMPA] = ADC_CLOCK_PERIOD / 2; // 50% duty
    pwmss0_regs[AQCTLA] = ADC_AQ;
}