ColorPAL sensor does not respond properly to yellow

alanluck2001

Hi - Red and blue are detected just fine, but yellow produces burned orange or amber colors. It's running at 5v, also tried it at 3.3 with same result. Anyone seen this or have a resolution? I am running Arduino 1.05 with the following code on an Uno. Thanks! /* ColorPal Sensor Example
* Author.... Martin Heermance based upon Phil Pilgrim's PBASIC example
* with some assistance from Gordon McComb.
* This program drives the Parallax ColorPAL color sensor and provides
* serial RGB data to the PC-hosted TCS230_ColorPAL_match.exe color
* matching program.
*/
#include <SoftwareSerial.h>
// I/O Pin definitions.
const int sio = 2;
const int unused = 255; // non-existant pin value
const int sioBaud = 4800;
// Received RGB values from ColorPAL.
int red;
int grn;
int blu;
// Set up two software serials on the same pin.
// This mimic PBASIC's serin and serout function.
SoftwareSerial serin(sio, unused);
SoftwareSerial serout(unused, sio);
//

---

[ Initialization ]

---

void setup()
{
// initialize serial communication:
Serial.begin(9600);

// Reset the ColorPAL and enter direct command mode.
reset();

// Program ColorPAL to send $ then color data.
serout.begin(sioBaud);
pinMode(sio, OUTPUT);
serout.print("= (00 $ m) !"); // buffer commmands, loop print $ and data end_loop now execute
// serout is unused from this point forwards
serout.end();
// Now turn the sio pin into an input to read data from the color pal.
serin.begin(sioBaud);
pinMode(sio, INPUT);
}
//

---

[ Program Code ]

---

// SERIN sio, baud, [WAIT("$"), HEX3 red, HEX3 grn, HEX3 blu] ' Receive RGB data back.
void loop()
{
readData();
}
//

---

[ Subroutines ]

---

// reset: Sends a long break to reset ColorPAL and enter direct command mode.
void reset()
{
pinMode(sio, OUTPUT);
digitalWrite(sio, LOW); // Pull sio low to eliminate any residual charge.
pinMode(sio, INPUT); // Return pin to input.
while (digitalRead(sio) != HIGH); // Wait for pin to be pulled high by ColorPAL.
pinMode(sio, OUTPUT);
digitalWrite(sio, LOW); // Pull pin low.
delay(80); // Keep low for 80ms to enter Direct mode.
pinMode(sio, INPUT); // Return pin to input.
delay(10); // Pause another 10ms
}
void readData()
{
char buffer[32];

if (serin.available() > 0)
{
// Wait for a $ and then read three 3 digit hex numbers
buffer[0] = serin.read();
if (buffer[0] == '$')
{
for(int i = 0; i < 9; i++)
{
// Wait for the next input character.
while (serin.available() == 0);
buffer = serin.read();
// every so often the data terminates early. If this happens return
if (buffer == '$')
return;
}
parseAndPrint(buffer);
delay(10);
}
}
}
void parseAndPrint(char * data)
{
// parse the hex data into integers.
sscanf (data, "%3x%3x%3x", &red, &grn, &blu);
// format using the format expected by the windows program and output it.
char buffer[32];
sprintf(buffer, "R%4.4d G%4.4d B%4.4d", red, grn, blu);
Serial.println(buffer);
}

GordonMcComb

Be sure to calibrate the ColorPAL each time you use it -- set the black and white balance first. These are buttons in the match.exe program for doing this. Otherwise colors may be off. Or, if you're not using that application, you have to write the black/white color balance adjustment routines yourself.