I am new to Arduino.
I have a I2C 1602 LCD module.
It works.
I am trying to use it with your code.
I had to comment out 2 lines to get it to compile.
If you could look at it and tell me if I need to modify this code for it to work.
Thanks so much for your time.
#include <avr/eeprom.h>
//we have to change prescaler for the ADC to make the conversion happen faster
//this code section was suggested on the arduino forum
#define FASTADC 1
// defines for setting and clearing register bits
#ifndef cbi
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#endif
#ifndef sbi
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
#endif
//define the input and output pin we will use
#define DISCHARGE_PIN 3
#define ESR_PIN A0
#define PULSE_SMALL 3
#define PULSE_PIN 5
#define BUTTON_PIN 7
//function prototype
unsigned long measureESR(void);//measuring function, increases ADC to 16bit resolution through oversampling
//global variables
unsigned long esrSamples;
double miliVolt;
double esrVal;
double esrCal;
double vRef = 1.093;//voltage on the Vref pin (this sketch uses internal voltage reference 1.1V)
double current = 0.046200;//proper calibration can be done entering the right value for the current (U=I*R)
//idealy this is 0.05 A, this condition is fulfilled only if R10 is 100 Ohm, Vcc is exactly 5V and the transistor
//while fully saturated idealy is at 0 ohm.
//this is my display setup, I'm using Stephen Hobley's 3 wire setup and class
//exchange to what is good for you
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,16,2); // set the LCD address to 0x27 for a 16 chars and 2 line display
void setup(void)
{
lcd.begin(20,2);
//lcd.setLED2Pin(HIGH);
lcd.setCursor(0,0);
lcd.print("ESR meter");
lcd.setCursor(5,1);
lcd.print("version 0.1");
delay(1000);
lcd.print("Seting up...");
analogReference(INTERNAL);//setting vRef to internal reference 1.1V
pinMode(ESR_PIN, INPUT);//reading miliVolt
pinMode(PULSE_PIN, OUTPUT);
digitalWrite(PULSE_PIN,HIGH);//low enables T1
pinMode(DISCHARGE_PIN, OUTPUT);
digitalWrite(PULSE_PIN,HIGH);//low disables T2
pinMode(BUTTON_PIN,INPUT);//setting up for a button (will use this for zeroing)
digitalWrite(BUTTON_PIN,HIGH);//enabling the pull up on the button, when button pressed to the ground zeroes out the cable
delay(1000);
lcd.clear();
lcd.print("Please Wait...");
//seting prescaller to 32 for faster adc (500khz)
//at 500khz results are still looking good (same values as if 250khz ADC clock)
// the shorter the pulse on a small value capacitor it has no time to charge and denaturate de result
if (FASTADC) {
sbi(ADCSRA,ADPS2);
cbi(ADCSRA,ADPS1);
sbi(ADCSRA,ADPS0);
}
//reading calibration value, it will be ok if already calibrated, else it might be bogus depends on the content of EEPROM
//but will be ok after first calibration
eeprom_read_block((void*)&esrCal, (void*)0, sizeof(esrCal));
}
void loop(void)
{
//lcd.setLED1Pin(HIGH);
esrSamples = measureESR();//this function takes a while,)
// so we don't need other delay for the lcd (this functions time gives the refresh rate for display
miliVolt = (esrSamples * vRef) / 65.536;//calculating voltage on AIN0 pin
esrVal = (miliVolt)/current - esrCal;//calculate ESR in miliOhm
lcd.clear();
lcd.print(" V:");
lcd.print(miliVolt,4);
lcd.setCursor(13,0);
lcd.print("mV");
lcd.setCursor(0,1);
lcd.print("ESR:");
lcd.print(esrVal,4);
lcd.setCursor(13,1);
lcd.print("m");
lcd.print((char)244);
//for zeroing the cables, this can be quite a big resistance compared to the values we intend to measure
//so it is a good idea to try to reduce in any way possible this influence (short cables, soldering the cables, etc)
if(!digitalRead(BUTTON_PIN)){
lcd.clear();
lcd.print("Zeroing...");
esrCal = (miliVolt)/current;
lcd.print(" done!");
lcd.setCursor(0,1);
//writing calibration value into EEPROM so we don't have to calibrate on restart
eeprom_write_block((const void*)&esrCal, (void*)0, sizeof(esrCal));
lcd.print("saved to EEPROM");
delay(400);
}
}
//this is where the magic happens, it really works and gives some
//incredibly good results! if you need sub milivolt accuracy is a good way to go
//noise is good ;) if in doubt must read oversampling on ADC from AVR docs
unsigned long measureESR()
{
unsigned long samples = 0;
unsigned int acumulator = 0;
int i = 0;
//oversampling 4096 times (for 16 bit is 4^(desiredResolution - ADCresolution))
while(i < 4096) {
digitalWrite(DISCHARGE_PIN,LOW);//disable discharging
digitalWrite(PULSE_PIN,LOW);//making a miliVolt pulse of 50mA
delayMicroseconds(1);//on the scope it looks that after enabling the pulse a litle delay is
//recomended so the oscillations fade away
acumulator = analogRead(ESR_PIN);//reading value on AIN0
digitalWrite(PULSE_PIN,HIGH);//stopping pulse
digitalWrite(DISCHARGE_PIN,HIGH);//discharging the capacitors
delayMicroseconds(600);//waiting a bit longer to fully discharge before another pulse
samples += acumulator;//acumulating the readings
i++;
}
//we have samples, let's go and compute value
samples = samples >> 6;//decimating value
return samples;//all done returning sampled value
}