Basic PWM implementation [WIP]

extras/pwm/component.mk

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+# Component makefile for extras/pwm
+
+INC_DIRS += $(ROOT)extras/pwm
+
+# args for passing into compile rule generation
+extras/pwm_INC_DIR =  $(ROOT)extras/pwm
+extras/pwm_SRC_DIR =  $(ROOT)extras/pwm
+
+$(eval $(call component_compile_rules,extras/pwm))

extras/pwm/pwm.c

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+#include "pwm.h"
+
+#include <espressif/esp_common.h>
+#include <espressif/sdk_private.h>
+#include <FreeRTOS.h>
+#include <esp8266.h>
+
+typedef struct PWMPinDefinition
+{
+    uint8_t pin;
+    uint8_t divider;
+} PWMPin;
+
+typedef enum {
+    PERIOD_ON   = 0,
+    PERIOD_OFF  = 1
+} pwm_step_t;
+
+
+typedef struct pwmInfoDefinition
+{
+    uint8_t running;
+
+    uint16_t freq;
+    uint16_t dutyCicle;
+
+    /* private */
+    uint32_t _maxLoad;
+    uint32_t _onLoad;
+    uint32_t _offLoad;
+    pwm_step_t _step;
+
+    uint16_t usedPins;
+    PWMPin pins[8];
+} PWMInfo;
+
+static PWMInfo pwmInfo;
+
+void frc1_interrupt_handler(void)
+{
+    uint8_t i = 0;
+    bool out = true;
+    uint32_t load = pwmInfo._onLoad;
+    pwm_step_t step = PERIOD_ON;
+
+    if (pwmInfo._step == PERIOD_ON)
+    {
+        out = false;
+        load = pwmInfo._offLoad;
+        step = PERIOD_OFF;
+    }
+
+    for (; i < pwmInfo.usedPins; ++i)
+    {
+        gpio_write(pwmInfo.pins[i].pin, out);
+    }
+
+    timer_set_load(FRC1, load);
+    pwmInfo._step = step;
+}
+
+void pwm_init(uint8_t npins, uint8_t* pins)
+{
+    /* Assert number of pins is correct */
+    if (npins > MAX_PWM_PINS)
+    {
+        printf("Incorrect number of PWM pins (%d)\n", npins);
+        return;
+    }
+
+    /* Initialize */
+    pwmInfo._maxLoad = 0;
+    pwmInfo._onLoad = 0;
+    pwmInfo._offLoad = 0;
+    pwmInfo._step = PERIOD_ON;
+
+    /* Save pins information */
+    pwmInfo.usedPins = npins;
+
+    uint8_t i = 0;
+    for (; i < npins; ++i)
+    {
+        pwmInfo.pins[i].pin = pins[i];
+
+        /* configure GPIOs */
+        gpio_enable(pins[i], GPIO_OUTPUT);
+    }
+
+    /* Stop timers and mask interrupts */
+    pwm_stop();
+
+    /* set up ISRs */
+    _xt_isr_attach(INUM_TIMER_FRC1, frc1_interrupt_handler);
+
+    /* Flag not running */
+    pwmInfo.running = 0;
+}
+
+void pwm_set_freq(uint16_t freq)
+{
+    pwmInfo.freq = freq;
+
+    /* Stop now to avoid load being used */
+    if (pwmInfo.running)
+    {
+        pwm_stop();
+        pwmInfo.running = 1;
+    }
+
+    timer_set_frequency(FRC1, freq);
+
+    if (pwmInfo.running)
+    {
+        pwm_start();
+    }
+}
+
+void pwm_set_duty(uint16_t duty)
+{
+    pwmInfo.dutyCicle = duty;
+    pwm_restart();
+}
+
+void pwm_restart()
+{
+    if (pwmInfo.running)
+    {
+        pwm_stop();
+        pwm_start();
+    }
+}
+
+void pwm_start()
+{
+    pwmInfo._maxLoad = timer_get_load(FRC1);
+    pwmInfo._onLoad = pwmInfo.dutyCicle * pwmInfo._maxLoad / UINT16_MAX;
+    pwmInfo._offLoad = pwmInfo._maxLoad - pwmInfo._onLoad;
+    pwmInfo._step = PERIOD_ON;
+
+    // Trigger ON
+    uint8_t i = 0;
+    for (; i < pwmInfo.usedPins; ++i)
+    {
+        gpio_write(pwmInfo.pins[i].pin, true);
+    }
+
+    timer_set_load(FRC1, pwmInfo._onLoad);
+    timer_set_reload(FRC1, false);
+    timer_set_interrupts(FRC1, true);
+    timer_set_run(FRC1, true);
+
+    pwmInfo.running = 1;
+}
+
+void pwm_stop()
+{
+    timer_set_interrupts(FRC1, false);
+    timer_set_run(FRC1, false);
+    pwmInfo.running = 0;
+}

extras/pwm/pwm.h

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+#include <stdint.h>
+
+#define MAX_PWM_PINS    8
+
+void pwm_init(uint8_t npins, uint8_t* pins);
+void pwm_set_freq(uint16_t freq);
+void pwm_set_duty(uint16_t duty);
+
+void pwm_restart();
+void pwm_start();
+void pwm_stop();