simple_pwm.c

#include "simple_pwm.h"
#include "hal_gpio.h"
#include "nrf.h"
#include "common_util.h"
#include "log.h"
#include "nrf_util.h"

#define TIMER_ID              CONCAT_2(NRF_TIMER, SIMPLE_PWM_TIMER_USED)
#define TIMER_IRQN            CONCAT_3(TIMER, SIMPLE_PWM_TIMER_USED, _IRQn)
#define TIMER_IRQ_Handler     CONCAT_3(TIMER, SIMPLE_PWM_TIMER_USED, _IRQHandler)

uint32_t pwm_pins[3];


void simple_pwm_init(simple_pwm_timer_freq_t freq,uint32_t max_count)
{
    TIMER_ID->TASKS_STOP = 1;
    TIMER_ID->TASKS_CLEAR = 1;

    //TODO Enable assertion
    //ASSERT((config->freq < 10) && (config->freq >= 0));
    TIMER_ID->PRESCALER = freq;

    //ASSERT((config->max_count > 2) && (config->max_count < 65536));
    TIMER_ID->BITMODE = TIMER_BITMODE_BITMODE_16Bit << TIMER_BITMODE_BITMODE_Pos;
    TIMER_ID->MODE = TIMER_MODE_MODE_Timer << TIMER_MODE_MODE_Pos;

    TIMER_ID->CC[SIMPLE_PWM_MAX_CHANNEL] = max_count;

    TIMER_ID->SHORTS = TIMER_SHORTS_COMPARE3_CLEAR_Enabled << TIMER_SHORTS_COMPARE3_CLEAR_Pos;

    TIMER_ID->EVENTS_COMPARE[SIMPLE_PWM_MAX_CHANNEL] = 0;
}

void simple_pwm_channel_setup(simple_pwm_channel_t channel, uint32_t pwm_out_pin, 
                              uint32_t value)
{
    if(value >= TIMER_ID->CC[SIMPLE_PWM_MAX_CHANNEL])
    {
        NRF_GPIOTE->CONFIG[channel+SIMPLE_PWM_GPIOTE_START_CH] =
                  (GPIOTE_CONFIG_MODE_Disabled << GPIOTE_CONFIG_MODE_Pos)
                | (pwm_pins[channel] << GPIOTE_CONFIG_PSEL_Pos)
                | (GPIOTE_CONFIG_POLARITY_Toggle << GPIOTE_CONFIG_POLARITY_Pos)
                | (GPIOTE_CONFIG_OUTINIT_Low << GPIOTE_CONFIG_OUTINIT_Pos);
        hal_gpio_pin_set(pwm_pins[channel]);
    }
    else if(value == 0)
    {
        NRF_GPIOTE->CONFIG[channel+SIMPLE_PWM_GPIOTE_START_CH] =
                  (GPIOTE_CONFIG_MODE_Disabled << GPIOTE_CONFIG_MODE_Pos)
                | (pwm_pins[channel] << GPIOTE_CONFIG_PSEL_Pos)
                | (GPIOTE_CONFIG_POLARITY_Toggle << GPIOTE_CONFIG_POLARITY_Pos)
                | (GPIOTE_CONFIG_OUTINIT_Low << GPIOTE_CONFIG_OUTINIT_Pos);
        hal_gpio_pin_clear(pwm_pins[channel]);
    }
    else
    {
        TIMER_ID->EVENTS_COMPARE[channel] = 0;
        hal_gpio_cfg_output(pwm_out_pin,0);
        pwm_pins[channel] = pwm_out_pin;

        NRF_PPI->CH[2*channel].EEP = (uint32_t) &(TIMER_ID->EVENTS_COMPARE[channel]);
        NRF_PPI->CH[2*channel].TEP = (uint32_t) &(NRF_GPIOTE->TASKS_CLR[channel+SIMPLE_PWM_GPIOTE_START_CH]);

        NRF_PPI->CH[2*channel+1].EEP = (uint32_t) &(TIMER_ID->EVENTS_COMPARE[SIMPLE_PWM_MAX_CHANNEL]);
        NRF_PPI->CH[2*channel+1].TEP = (uint32_t) &(NRF_GPIOTE->TASKS_SET[channel+SIMPLE_PWM_GPIOTE_START_CH]);
        
        NRF_GPIOTE->CONFIG[channel+SIMPLE_PWM_GPIOTE_START_CH] =
                  (GPIOTE_CONFIG_MODE_Task << GPIOTE_CONFIG_MODE_Pos)
                | (pwm_pins[channel] << GPIOTE_CONFIG_PSEL_Pos)
                | (GPIOTE_CONFIG_POLARITY_Toggle << GPIOTE_CONFIG_POLARITY_Pos)
                | (GPIOTE_CONFIG_OUTINIT_Low << GPIOTE_CONFIG_OUTINIT_Pos);
        TIMER_ID->CC[channel] = value;
    }
}

void simple_pwm_start ()
{
    NRF_PPI->CHENSET = (1<<0)|(1<<1)|(1<<2)|(1<<3)|(1<<4)|(1<<5);

    TIMER_ID->TASKS_START = 1;
}

void simple_pwm_stop ()
{
    NRF_PPI->CHENCLR = (1<<0)|(1<<1)|(1<<2)|(1<<3)|(1<<4)|(1<<5);
    
    TIMER_ID->TASKS_STOP = 1;

    TIMER_ID->TASKS_SHUTDOWN = 1;
}