refactor RGB LED

lab2.md

@@ -63,10 +63,6 @@ Start with this code skeleton:
 
 #include "ledutils.h"
 
-PwmOut ledR(P0_5);
-PwmOut ledG(P0_6);
-PwmOut ledB(P0_7);
-
 DigitalOut led1(P0_3);
 DigitalOut led2(P0_9);
 
@@ -77,11 +73,6 @@ RawSerial serial(P0_8, NC, 115200);
 CAN can(RXD_PIN, TXD_PIN);
 
 int main() {
-  // Start with RGB LED off
-  ledR = 1;
-  ledG = 1;
-  ledB = 1;
-
   // Initialize CAN controller at 1 Mbaud
   can.frequency(1000000);
 

solutions/lab2.2.cpp

@@ -2,10 +2,6 @@
 
 #include "ledutils.h"
 
-PwmOut ledR(P0_5);
-PwmOut ledG(P0_6);
-PwmOut ledB(P0_7);
-
 DigitalOut led1(P0_3);
 DigitalOut led2(P0_9);
 
@@ -16,11 +12,6 @@ RawSerial serial(P0_8, NC, 115200);
 CAN can(P0_28, P0_29);
 
 int main() {
-  // Start with RGB LED off
-  ledR = 1;
-  ledG = 1;
-  ledB = 1;
-
   // Initialize CAN controller at 1 Mbaud
   can.frequency(1000000);
 

solutions/lab2master.cpp

@@ -2,9 +2,7 @@
 
 #include "ledutils.h"
 
-PwmOut ledR(P0_5);
-PwmOut ledG(P0_6);
-PwmOut ledB(P0_7);
+RGBPwmOut rgbLed(P0_5, P0_6, P0_7);
 
 DigitalOut led1(P0_3);
 DigitalOut led2(P0_9);
@@ -19,11 +17,6 @@ const uint16_t DEBOUNCE_TIME_MS = 50;
 const uint16_t RGB_LED_UPDATE_MS = 20;  // a respectable 50 Hz
 
 int main() {
-  // Start with RGB LED off
-  ledR = 1;
-  ledG = 1;
-  ledB = 1;
-
   // LED Blink State
   int32_t blinkLengthMs;
   Timer ledTimer;  // used to track blink length
@@ -84,13 +77,7 @@ int main() {
       hue += RGB_LED_UPDATE_MS * 10;
       hue = hue % 36000;  // 360 degree * 100
 
-      uint16_t r, g, b;
-      hsv_to_rgb_pwm_uint16(hue, 65535, 65535, &r, &g, &b);
-
-      // Set outputs.
-      ledR.pulsewidth_us((uint32_t)r * 500 / 65535);
-      ledG.pulsewidth_us((uint32_t)g * 500 / 65535);
-      ledB.pulsewidth_us((uint32_t)b * 500 / 65535);
+      rgbLed.hsv_uint16(hue, 65535, 65535);
 
       // Update CAN with new hue.
       uint8_t data[2];

src/ledutils.cpp

@@ -53,8 +53,7 @@ void hsv_to_rgb_uint16(uint16_t h_cdeg, uint16_t s, uint16_t v,
   *b_out = *b_out + m;
 }
 
-void hsv_to_rgb_pwm_uint16(uint16_t h_cdeg, uint16_t s, uint16_t v,
-    uint16_t *r_out, uint16_t *g_out, uint16_t *b_out) {
+void RGBPwmOut::hsv_uint16(uint16_t h_cdeg, uint16_t s, uint16_t v) {
   uint16_t C = (uint32_t)v * s / 65535;
   int32_t h_millipct = (((int32_t)h_cdeg * 10 / 60) % 2000) - 1000;  // 1000x
   uint16_t X = C * (1000 - abs(h_millipct)) / 1000;
@@ -92,7 +91,7 @@ void hsv_to_rgb_pwm_uint16(uint16_t h_cdeg, uint16_t s, uint16_t v,
   b = 65535 - b;
 
   // Write outputs.
-  *r_out = r;
-  *g_out = g;
-  *b_out = b;
+  ledR.pulsewidth_us((uint32_t)r * PWM_PERIOD_US / 65535);
+  ledG.pulsewidth_us((uint32_t)r * PWM_PERIOD_US / 65535);
+  ledB.pulsewidth_us((uint32_t)r * PWM_PERIOD_US / 65535);
 }

src/ledutils.h

@@ -17,11 +17,33 @@ void hsv_to_rgb_float(float h_deg, float s, float v,
 void hsv_to_rgb_uint16(uint16_t h_cdeg, uint16_t s, uint16_t v,
     uint16_t *r_out, uint16_t *g_out, uint16_t *b_out);
 
-/* Converts H (centidegrees, [0, 36000)), S, V (in [0, 65535]),
- * to R, G, B (all in [0, 65535]) PWM, accounting for polarity inversion and
- * human perceived brightness
+/* Common-anode RGB LED controlled by PWM, with fixed-point options.
  */
-void hsv_to_rgb_pwm_uint16(uint16_t h_cdeg, uint16_t s, uint16_t v,
-    uint16_t *r_out, uint16_t *g_out, uint16_t *b_out);
+class RGBPwmOut {
+  RGBPwmOut(PinName pinR, PinName pinG, PinName pinB):
+    ledR(pinR), ledG(pinG), ledB(pinB) {
+    ledR.period_us(PWM_PERIOD_US);
+    ledG.period_us(PWM_PERIOD_US);
+    ledB.period_us(PWM_PERIOD_US);
+
+    // Initialize LEDs to off
+    ledR.pulsewidth_us(PWM_PERIOD_US);
+    ledG.pulsewidth_us(PWM_PERIOD_US);
+    ledB.pulsewidth_us(PWM_PERIOD_US);
+  }
+
+  /* Writes a HSV value to the RGB LED, accounting for polarity inversion and
+   * human perceived brightness
+   * H is in centidegrees, [0, 36000), S, V are in fixed point [0, 65535].
+   */
+  void hsv_uint16(uint16_t h_cdeg, uint16_t s, uint16_t v);
+
+protected:
+  static const uint16_t PWM_PERIOD_US = 500;
+
+  PwmOut ledR;
+  PwmOut ledG;
+  PwmOut b;
+};
 
 #endif /* LEDUTILS_H_ */