fix RGB LED code

lab2.md

@@ -122,7 +122,9 @@ can.write(CANMessage(0x42));
 Have your edge detection code execute the above on a button press, and you should be done. Feel free to compare against the [solution](solutions/lab2.2.cpp), too.
 
 ## Lab 2.3: CAN Messages with Data
+When the master node receives a CAN message with ID 0x41, it will pulse its white LED with a length specified by the data field, in milliseconds. The blink length is the first 16-bit integer in the payload, in [big-endian (network order)](https://en.wikipedia.org/wiki/Endianness#Networking) format.
 
+**Objective**: When the button is pressed on your BRAIN, have it transmit a message that triggers a blink on the remote master node at some interesting amount of time (not 250ms as the last lab).
 
 ## Lab 2.4: Receiving CAN Messages
 Receive a regularly-sent message with a particular ID which sets the RGB LED hue and intensity, allowing all the bus lights to be synchronized.

solutions/lab2.4.cpp

@@ -0,0 +1,29 @@
+#include "mbed.h"
+
+#include "ledutils.h"
+
+RGBPwmOut rgbLed(P0_5, P0_6, P0_7);
+
+DigitalOut led1(P0_3);
+DigitalOut led2(P0_9);
+
+DigitalIn btn(P0_4);
+
+RawSerial serial(P0_8, NC, 115200);
+
+CAN can(P0_28, P0_29);
+
+int main() {
+  // Initialize CAN controller at 1 Mbaud
+  can.frequency(1000000);
+
+  while (true) {
+    CANMessage msg;
+    while (can.read(msg)) {
+      if (msg.id == 0x43) {
+        uint16_t hue = (msg.data[0] << 8) | (msg.data[1] << 0);
+        rgbLed.hsv_uint16(hue, 65535, 65535);
+      }
+    }
+  }
+}

solutions/lab2master.cpp

@@ -18,17 +18,13 @@ const uint16_t RGB_LED_UPDATE_MS = 20;  // a respectable 50 Hz
 
 int main() {
   // LED Blink State
-  int32_t blinkLengthMs;
+  int32_t blinkLengthMs = 0;
   Timer ledTimer;  // used to track blink length
   ledTimer.start();
 
   bool lastButton = true;
   Timer buttonDebounceTimer;
 
-  ledR.period_us(500);
-  ledG.period_us(500);
-  ledB.period_us(500);
-
   uint16_t hue = 0;
   Timer rgbLedTimer;
   rgbLedTimer.start();
@@ -42,8 +38,12 @@ int main() {
     while (can.read(msg)) {
       if (msg.id == 0x42) {
         led2 = 1;
+        ledTimer.reset();
         blinkLengthMs = 250;
+      } else if (msg.id == 0x41) {
+        led2 = 1;
         ledTimer.reset();
+        blinkLengthMs = (msg.data[0] << 8) | msg.data[1];
       }
     }
 
@@ -77,7 +77,7 @@ int main() {
       hue += RGB_LED_UPDATE_MS * 10;
       hue = hue % 36000;  // 360 degree * 100
 
-      rgbLed.hsv_uint16(hue, 65535, 65535);
+      rgbLed.hsv_uint16(hue, 65535, 32767);
 
       // Update CAN with new hue.
       uint8_t data[2];

src/ledutils.cpp

@@ -92,6 +92,6 @@ void RGBPwmOut::hsv_uint16(uint16_t h_cdeg, uint16_t s, uint16_t v) {
 
   // Write outputs.
   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);
+  ledG.pulsewidth_us((uint32_t)g * PWM_PERIOD_US / 65535);
+  ledB.pulsewidth_us((uint32_t)b * PWM_PERIOD_US / 65535);
 }

src/ledutils.h

@@ -6,6 +6,8 @@
 
 #include <stdint.h>
 
+#include "mbed.h"
+
 /* Converts H (degrees, [0, 360)), S, V (in [0, 1]), to R, G, B (all in [0, 1])
  */
 void hsv_to_rgb_float(float h_deg, float s, float v,
@@ -20,6 +22,7 @@ void hsv_to_rgb_uint16(uint16_t h_cdeg, uint16_t s, uint16_t v,
 /* Common-anode RGB LED controlled by PWM, with fixed-point options.
  */
 class RGBPwmOut {
+public:
   RGBPwmOut(PinName pinR, PinName pinG, PinName pinB):
     ledR(pinR), ledG(pinG), ledB(pinB) {
     ledR.period_us(PWM_PERIOD_US);
@@ -43,7 +46,7 @@ class RGBPwmOut {
 
   PwmOut ledR;
   PwmOut ledG;
-  PwmOut b;
+  PwmOut ledB;
 };
 
 #endif /* LEDUTILS_H_ */