Add ability to set led color

app/prj.conf

@@ -8,3 +8,4 @@ CONFIG_JSON_LIBRARY=y
 CONFIG_FLASH=y
 CONFIG_FLASH_MAP=y
 CONFIG_FCB=y
+CONFIG_PWM=y

app/src/alerts.c

@@ -13,11 +13,27 @@
 #include <alerts.h>
 #include <logging/log.h>
 #include <zephyr.h>
+#include <device.h>
+#include <drivers/pwm.h>
+
 LOG_MODULE_REGISTER(alerts, CONFIG_PYRRHA_LOG_LEVEL);
+
 #define OVER_TEMPERATURE(temp) (temp > CONFIG_TEMPERATURE_ALERT_THRESHOLD_CELCIUS)
 #define OVER_CO(co) (co > CONFIG_CO_ALERT_THRESHOLD_PPM)
 #define OVER_NO2(no2) (no2 > CONFIG_NO2_ALERT_THRESHOLD_PPM)
 
+/*
+ * 50hz is flicker fusion threshold. Modulated light will be perceived
+ * as steady by our eyes when blinking rate is at least 50.
+ */
+#define PERIOD_USEC	(USEC_PER_SEC / 50U)
+
+#define RED_LED_NODE DT_ALIAS(red_pwm_led)
+#define GREEN_LED_NODE DT_ALIAS(green_pwm_led)
+#define BLUE_LED_NODE DT_ALIAS(blue_pwm_led)
+
+#define COLOR_TO_PULSE(color, period)         (color == UINT8_MAX ? (period) : (color * (period) >> 8))
+
 /**
  * @brief union which allows easy set/conversion to hex or rgb directly
  * 
@@ -31,9 +47,75 @@ typedef union Color{
     };
 }color_t;
 
+/**
+ * @brief Configuration table for pwm led
+ * 
+ */
+struct pwm_cfg{
+    const struct device * pwm;
+    const uint8_t pin;
+    const uint8_t flags;
+    const uint32_t period;
+};
+
+/**
+ * @brief Container for all pwm leds associated with the rgb led
+ * 
+ */
+struct rgb_led_device{
+    const struct pwm_cfg red;
+    const struct pwm_cfg green;
+    const struct pwm_cfg blue;
+};
+
 K_MUTEX_DEFINE(mtx_alert);
 static color_t g_alert_override = {0};
 
+const struct rgb_led_device g_led = {
+    .red = {
+        .pwm = DEVICE_DT_GET(DT_PWMS_CTLR(RED_LED_NODE)),
+        .pin = DT_PWMS_CHANNEL(RED_LED_NODE),
+        .flags = DT_PWMS_FLAGS(RED_LED_NODE), 
+        .period = PERIOD_USEC
+    },
+    .green = {
+        .pwm = DEVICE_DT_GET(DT_PWMS_CTLR(GREEN_LED_NODE)),
+        .pin = DT_PWMS_CHANNEL(GREEN_LED_NODE),
+        .flags = DT_PWMS_FLAGS(GREEN_LED_NODE), 
+        .period = PERIOD_USEC
+    },
+    .blue = {
+        .pwm = DEVICE_DT_GET(DT_PWMS_CTLR(BLUE_LED_NODE)),
+        .pin = DT_PWMS_CHANNEL(BLUE_LED_NODE),
+        .flags = DT_PWMS_FLAGS(BLUE_LED_NODE), 
+        .period = PERIOD_USEC
+    },
+};
+
+/**
+ * @brief Set pwm output directly to the coresponding 8-bit color value
+ * 
+ * @param cfg : configuration table for pwm device
+ * @param color : 8-bit color value for the specified pwm
+ * @retval 0 on success
+ * @retval -ENODEV if no configuration table
+ * @retval -EFAULT if pwm set error
+ */
+static int set_pwm(const struct pwm_cfg * cfg, uint8_t color)
+{
+    if (cfg == NULL){
+        return -ENODEV;
+    }
+	const struct device *dev = cfg->pwm;
+    uint32_t pulse = COLOR_TO_PULSE(color, cfg->period);
+	/* Verify pwm_pin_set_usec() */
+	if (pwm_pin_set_usec(dev, cfg->pin, cfg->period, pulse, cfg->flags)) {
+		LOG_ERR("Fail to set the period and pulse width");
+		return -EFAULT;
+	}
+	return 0;
+}
+
 /**
  * @brief Set the alert led to a specific color
  * 
@@ -42,6 +124,9 @@ static color_t g_alert_override = {0};
  * @retval -errno otherwise
  */
 static int set_alert_led(color_t color){
+    set_pwm(&g_led.red, color.red);
+    set_pwm(&g_led.green, color.green);
+    set_pwm(&g_led.blue, color.blue);
     return 0;
 }