RGB Values over 255 when using the TCS34725 RGB sensor

Using Arduino Sensors
1

I'm getting RGB values above 255 and I'm not sure how to interpret these values. Is there something wrong in my code?

#include <Wire.h>
#include "Adafruit_TCS34725.h"
 
/* Example code for the Adafruit TCS34725 breakout library */
 
/* Connect SCL to analog 5
Connect SDA to analog 4
Connect VDD to 3.3V DC
Connect GROUND to common ground */
 
/* Initialise with default values (int time = 2.4ms, gain = 1x) */
// Adafruit_TCS34725 tcs = Adafruit_TCS34725();
 
/* Initialise with specific int time and gain values */
Adafruit_TCS34725 tcs = Adafruit_TCS34725(TCS34725_INTEGRATIONTIME_614MS, TCS34725_GAIN_1X);
 
void setup(void) {
Serial.begin(9600);
 
if (tcs.begin()) {
Serial.println("Found sensor");
} else {
Serial.println("No TCS34725 found ... check your connections");
while (1);
}
 
// Now we're ready to get readings!
}
 
void loop(void) {
uint16_t r, g, b, c, colorTemp, lux;
 
tcs.getRawData(&r, &g, &b, &c);
colorTemp = tcs.calculateColorTemperature(r, g, b);
lux = tcs.calculateLux(r, g, b);
 
Serial.print("Color Temp: "); Serial.print(colorTemp, DEC); Serial.print(" K - ");
Serial.print("Lux: "); Serial.print(lux, DEC); Serial.print(" - ");
Serial.print("R: "); Serial.print(r, DEC); Serial.print(" ");
Serial.print("G: "); Serial.print(g, DEC); Serial.print(" ");
Serial.print("B: "); Serial.print(b, DEC); Serial.print(" ");
Serial.print("C: "); Serial.print(c, DEC); Serial.print(" ");
Serial.println(" ");
}

Example output: 12:24:42.459 -> Color Temp: 8643 K - Lux: 795 - R: 961 G: 1240 B: 1161 C: 2866
How do i fix this? Thanks in advance!

2

Read the documentation, and find the RGB maximum values (the range of values). Then scale the values to 0-255 by multiplying by 256 and dividing by the maximum values.

It's simple scaling.

You didn't say why you wanted to scale it, you will lose precision that way.

3

Those numbers are fine -

This “ uint16_t” tells you they are 16bit numbers , scaled 0 to 65535 , not 0-255.

“ Colour temperature is measured in Kelvins (K), and typically ranges from 2000K-6500K. The lower the number, the warmer the light. A typical warm white light bulb for use in living rooms and bedrooms would have a colour temperature between 2700K-3200K. Cool white bulbs are anywhere upwards of 4000K. At the far end of the scale, ‘daylight’ bulbs have a colour temperature of 6500K and are supposed to replicate the tone of light that the sun emits during the day. These would look very blue in a typical living room.”

4

Agreed. The sensor is operating correctly. The data sheet explains the sensor operation very clearly.

5

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.