Corr. of function converting hex digit to binary

Author: tomekmalek

examples/7_distance_and_light_sensor/7_distance_and_light_sensor.ino

@@ -12,8 +12,8 @@ uint32_t messageRate = 5000;   // stores the current data message rate in Millis
 unsigned long lastMessageTime = 0;   // stores the time when last data message was sent
 
 VL6180x sensor(VL6180X_ADDRESS);
-char ambient_light[20];     // ambient light level [lx]
 u_int8_t distance;          // distance from obstruction [mm]
+float ambient_light;        // ambient light [lx]
 
 /******************************************************************************
    USER PROGRAM
@@ -27,7 +27,7 @@ void setup() {
   Serial.print(SW_REVISION);
   Serial.println(" ***");
   lo.setSecurity(TLS);
-  lo.begin(MQTT, TEXT, true);
+  lo.begin(MQTT, BINARY, true);
   lo.connect(); // connects to the network + Live Objects
 }
 
@@ -37,10 +37,10 @@ void loop() {
     Serial.println("Sampling data");
 
     distance = sensor.getDistance();
-    lo.addToPayload("distance", distance);               // adding 'distance' value to the current payload
-    sprintf(ambient_light, "%.2f", sensor.getAmbientLight(GAIN_1));
-    lo.addToPayload("ambient_light", ambient_light);     // adding 'ambient_light' value to the current payload
-    
+    lo.addToPayload(distance);               // adding 'distance' value to the current payload
+    ambient_light = (static_cast<int>(sensor.getAmbientLight(GAIN_1) * 100.0)) / 100.0;
+    lo.addToPayload(ambient_light);
+
     Serial.println("Sending data to Live Objects");
     lo.sendData();                                   // send the data to Live Objects
     lastMessageTime = millis();

src/Utils.cpp

@@ -46,13 +46,18 @@ String ToHex(String x)
 
 uint8_t hexBinary(char msb, char lsb)
 {
+  auto capitalizeChar = [](char x)
+  {
+    if((x >= 'a') && (x <= 'f')) return (x - ' ');  // eg. 'a'(0x61) - ' ' (0x20) -> 'A'(0x41)
+    else return x - static_cast<char>(0);
+  };
   auto hexToDec = [](char x)
   {
-    if(x>='a' && x<='f') return 10 + (x-'a');
-    else return x-'0';
+    if((x >= 'A') && (x <= 'F')) return 10 + (x - 'A'); // only capital hex digits
+    else return x - '0';
   };
 
-  return (hexToDec(msb)<<4)|hexToDec(lsb); 
+  return (hexToDec(capitalizeChar(msb)) << 4) | hexToDec(capitalizeChar(lsb)); 
 }
 
 String to7bit(String inputString)