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80 lines
2.9 KiB
80 lines
2.9 KiB
/* |
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Example using the SparkFun HX711 breakout board with a scale |
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By: Nathan Seidle |
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SparkFun Electronics |
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Date: November 19th, 2014 |
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License: This code is public domain but you buy me a beer if you use this and we meet someday (Beerware license). |
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This is the calibration sketch. Use it to determine the calibration_factor that the main example uses. It also |
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outputs the zero_factor useful for projects that have a permanent mass on the scale in between power cycles. |
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Setup your scale and start the sketch WITHOUT a weight on the scale |
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Once readings are displayed place the weight on the scale |
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Press +/- or a/z to adjust the calibration_factor until the output readings match the known weight |
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Use this calibration_factor on the example sketch |
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This example assumes pounds (lbs). If you prefer kilograms, change the Serial.print(" lbs"); line to kg. The |
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calibration factor will be significantly different but it will be linearly related to lbs (1 lbs = 0.453592 kg). |
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Your calibration factor may be very positive or very negative. It all depends on the setup of your scale system |
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and the direction the sensors deflect from zero state |
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This example code uses bogde's excellent library: https://github.com/bogde/HX711 |
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bogde's library is released under a GNU GENERAL PUBLIC LICENSE |
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Arduino pin 2 -> HX711 CLK |
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3 -> DOUT |
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5V -> VCC |
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GND -> GND |
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Most any pin on the Arduino Uno will be compatible with DOUT/CLK. |
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The HX711 board can be powered from 2.7V to 5V so the Arduino 5V power should be fine. |
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*/ |
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#include "HX711.h" |
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#define DOUT 30 |
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#define CLK 27 |
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HX711 scale; |
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float calibration_factor = -7050; //-7050 worked for my 440lb max scale setup |
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void setup() { |
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Serial.begin(115200); |
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Serial.println("HX711 calibration sketch"); |
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Serial.println("Remove all weight from scale"); |
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Serial.println("After readings begin, place known weight on scale"); |
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Serial.println("Press + or a to increase calibration factor"); |
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Serial.println("Press - or z to decrease calibration factor"); |
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scale.begin(DOUT, CLK); |
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digitalWrite(CLK, LOW); // hangs without this |
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scale.set_scale(); |
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scale.tare(); //Reset the scale to 0 |
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long zero_factor = scale.read_average(); //Get a baseline reading |
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Serial.print("Zero factor: "); //This can be used to remove the need to tare the scale. Useful in permanent scale projects. |
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Serial.println(zero_factor); |
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} |
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void loop() { |
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scale.set_scale(calibration_factor); //Adjust to this calibration factor |
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Serial.print("Reading: "); |
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Serial.print(scale.get_units(), 1); |
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Serial.print(" lbs"); //Change this to kg and re-adjust the calibration factor if you follow SI units like a sane person |
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Serial.print(" calibration_factor: "); |
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Serial.print(calibration_factor); |
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Serial.println(); |
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if(Serial.available()) |
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{ |
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char temp = Serial.read(); |
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if(temp == '+' || temp == 'a') |
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calibration_factor += 10; |
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else if(temp == '-' || temp == 'z') |
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calibration_factor -= 10; |
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} |
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}
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