Hi guys,
I follow this page "SHARP GP2Y1014A0U Demo" to made a PM 2.5 sensor monitor, and I find the analog read issue.
When I follow the information to connection the circuit and using the example code try to show the PM2.5 value, I can find the PM2.5 value in the IDE serial monitor, but the value look is wrong.
When I remove the PM2.5 sensor and using wire connect the analog pin to GND, the serial monitor can show the random value to me, I try to search same information in there, I find some guys suggestion using connect a resist (148K ohm) between the analog pin and GND.
I try to follow the solution to solve the issue, I can get "0" when I check by using the IDE serial monitor, but when I connection the PM2.5 sensor, the value is wrong and the value is random.
Have any guys can give me any ways to solve this issue ?
Thx.
Environment:
OS:Win 10
IDE: Arduino 1.8.7
Board: UNO
PM2.5 Sensor: SHARP GP2Y1014A0U
It would help if you posted your code, and a sample of the output. Remember to use code tags when posting.
Hi Metallor,
Thank you for your reminder.
The source code is below:
/////////////////////////////////////////////////////////////////////////////
// Sharp GP2Y1014AU0F Dust Sensor Demo
//
// Board Connection:
// GP2Y1014 Arduino
// V-LED Between R1 and C1
// LED-GND C1 and GND
// LED Pin 7
// S-GND GND
// Vo A5
// Vcc 5V
//
// Serial monitor setting:
// 9600 baud
/////////////////////////////////////////////////////////////////////////////
// Choose program options.
//#define PRINT_RAW_DATA
#define USE_AVG
// Arduino pin numbers.
const int sharpLEDPin = 7; // Arduino digital pin 7 connect to sensor LED.
const int sharpVoPin = A5; // Arduino analog pin 5 connect to sensor Vo.
// For averaging last N raw voltage readings.
#ifdef USE_AVG
#define N 100
static unsigned long VoRawTotal = 0;
static int VoRawCount = 0;
#endif // USE_AVG
// Set the typical output voltage in Volts when there is zero dust.
static float Voc = 0.6;
// Use the typical sensitivity in units of V per 100ug/m3.
const float K = 0.5;
/////////////////////////////////////////////////////////////////////////////
// Helper functions to print a data value to the serial monitor.
void printValue(String text, unsigned int value, bool isLast = false) {
Serial.print(text);
Serial.print("=");
Serial.print(value);
if (!isLast) {
Serial.print(", ");
}
}
void printFValue(String text, float value, String units, bool isLast = false) {
Serial.print(text);
Serial.print("=");
Serial.print(value);
Serial.print(units);
if (!isLast) {
Serial.print(", ");
}
}
/////////////////////////////////////////////////////////////////////////////
// Arduino setup function.
void setup() {
// Set LED pin for output.
pinMode(sharpLEDPin, OUTPUT);
// Start the hardware serial port for the serial monitor.
Serial.begin(9600);
// Wait two seconds for startup.
delay(2000);
Serial.println("");
Serial.println("GP2Y1014AU0F Demo");
Serial.println("=================");
}
// Arduino main loop.
void loop() {
// Turn on the dust sensor LED by setting digital pin LOW.
digitalWrite(sharpLEDPin, LOW);
// Wait 0.28ms before taking a reading of the output voltage as per spec.
delayMicroseconds(280);
// Record the output voltage. This operation takes around 100 microseconds.
int VoRaw = analogRead(sharpVoPin);
// Turn the dust sensor LED off by setting digital pin HIGH.
digitalWrite(sharpLEDPin, HIGH);
// Wait for remainder of the 10ms cycle = 10000 - 280 - 100 microseconds.
delayMicroseconds(9620);
// Print raw voltage value (number from 0 to 1023).
#ifdef PRINT_RAW_DATA
printValue("VoRaw", VoRaw, true);
Serial.println("");
#endif // PRINT_RAW_DATA
// Use averaging if needed.
float Vo = VoRaw;
#ifdef USE_AVG
VoRawTotal += VoRaw;
VoRawCount++;
if ( VoRawCount >= N ) {
Vo = 1.0 * VoRawTotal / N;
VoRawCount = 0;
VoRawTotal = 0;
} else {
return;
}
#endif // USE_AVG
// Compute the output voltage in Volts.
Vo = Vo / 1024.0 * 5.0;
printFValue("Vo", Vo*1000.0, "mV");
// Convert to Dust Density in units of ug/m3.
float dV = Vo - Voc;
if ( dV < 0 ) {
dV = 0;
Voc = Vo;
}
float dustDensity = dV / K * 100.0;
printFValue("DustDensity", dustDensity, "ug/m3", true);
Serial.println("");
} // END PROGRAM
How do you determine whether the readout is wrong or right? Do you have a sample of your output?