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260 | #include <avr/io.h>
#include <util/delay.h>
#include <EEPROM.h>
#include <SPI.h>
#include <Wire.h>
#include <MCP342x.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
// ---------------------------------------------------------------------------------------------
// some macros definitions
// ---------------------------------------------------------------------------------------------
#define setPin(b) ( (b)<8 ? PORTD |=(1<<(b)) : PORTB |=(1<<(b-8)) )
#define setPinAnalog(b) ( PORTC |=(1<<(b)) )
#define clrPin(b) ( (b)<8 ? PORTD &=~(1<<(b)) : PORTB &=~(1<<(b-8)) )
#define clrPinAnalog(b) ( PORTC &=~(1<<(b)) )
#define tstPin(b) ( (b)<8 ? (PORTD &(1<<(b)))!=0 : (PORTB &(1<<(b-8)))!=0 )
#define tstPinAnalog(b) ( (PORTC &(1<<(b)))!=0 )
#define FastDigitalWrite(b,How) if (How) setPin(b); else clrPin(b)
#ifndef F_CPU
#define F_CPU 16000000UL
#endif
// ---------------------------------------------------------------------------------------------
// pins definition
// ---------------------------------------------------------------------------------------------
#define BUZZER 6
#define BUTTON 3
#define TRANSISTOR 3
#define AOP 2
// ---------------------------------------------------------------------------------------------
// display constants for a 128x32 oled module
// ---------------------------------------------------------------------------------------------
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 32 // OLED display height, in pixels
#define OLED_RESET 4 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
// ---------------------------------------------------------------------------------------------
// analog to digital constants
// ---------------------------------------------------------------------------------------------
// 0x68 is the default address for all MCP342x devices
uint8_t address = 0x68;
MCP342x adc = MCP342x(address);
unsigned long probes_compensation; // 80mohms de sonde => 1V sortie aop, 5mV par count
unsigned long adc_val; // 0-65535+
unsigned int button_delay; // to detect long press of the button
float Vbat;
float Rx;
void setup( void)
{
Serial.begin(9600); // open the serial port at 9600 bps:
pinMode( BUTTON, INPUT_PULLUP); // input en D3 button
pinMode( BUZZER, OUTPUT); // output on D6 buzzer
PORTD |= (1 << PORTD3);
DDRC |= (1 << DDC3); // analog output 3 for pnp seeding
DDRB |= (1 << DDC2); // analog input 2 for adc sampling
DDRB |= (1 << DDC0); // analog input 0 for adc vbat
PORTC &= ~(1 << PORTC3);
ADCSRA = (1 << ADEN) | (1 << ADPS2) | (1 << ADPS0); // sets adc prescaler to 16 for max speed
// ---------------------------------------------------------------------------------------------
// reads the stored probe compensation from the arduino eeprom
// ---------------------------------------------------------------------------------------------
probes_compensation = EEPROM.read( 0); // read probes compensation value from eeprom at startup
probes_compensation += EEPROM.read( 1) << 8;
probes_compensation += EEPROM.read( 2) << 16;
probes_compensation += EEPROM.read( 3) << 24;
//Serial.print("Probes:");Serial.println(probes_compensation);
noTone( BUZZER);
Wire.begin(); // join I2C bus
// ---------------------------------------------------------------------------------------------
// initialize mcp3421 ADC
// ---------------------------------------------------------------------------------------------
MCP342x::generalCallReset();
delay(1); // MC342x needs 300us to settle, wait 1ms
// ---------------------------------------------------------------------------------------------
// initialize OLED display
// ---------------------------------------------------------------------------------------------
display.begin(SSD1306_SWITCHCAPVCC, 0x3c, 0); // initialize display @ address 0x3c, no reset
display.clearDisplay();
display.display();
// ---------------------------------------------------------------------------------------------
// powers pnp transistor
// ---------------------------------------------------------------------------------------------
clrPinAnalog( TRANSISTOR);
_delay_ms(1);
}
void loop (void)
{
// ---------------------------------------------------------------------------------------------
// measures battery voltage
// ---------------------------------------------------------------------------------------------
Vbat = analogRead(A0)*10.0/1024.0; // 2:1 divider (10V FS) on 9V battery
// ---------------------------------------------------------------------------------------------
// read ADC mcp3421 from i2c bus
// ---------------------------------------------------------------------------------------------
long value = 0;
MCP342x::Config status;
// Initiate a conversion; convertAndRead() will wait until it can be read
uint8_t err = adc.convertAndRead(MCP342x::channel1, MCP342x::oneShot,
MCP342x::resolution16, MCP342x::gain1, 1000000, value, status);
adc_val = value;
// ---------------------------------------------------------------------------------------------
// reads button state to engage REL mode
// ---------------------------------------------------------------------------------------------
if (digitalRead( BUTTON) == 0) // check D3 button state
{
noTone( BUZZER);
display.clearDisplay();
DisplayStr("REL");
display.display();
delay(500);
probes_compensation = adc_val;
button_delay = 0;
while ((digitalRead( BUTTON) == 0) && (button_delay<10))
{
button_delay++;
delay(100);
}
// ---------------------------------------------------------------------------------------------
// stores probe compensation in eeprom if long press button
// ---------------------------------------------------------------------------------------------
if (button_delay>8)
{
display.clearDisplay();
DisplayStr("STORE");
display.display();
delay(500);
EEPROM.update( 0, (byte) adc_val); // stores probes compensation value in eeprom if different
EEPROM.update( 1, (byte) adc_val >> 8);
EEPROM.update( 2, (byte) adc_val >> 16);
EEPROM.update( 3, (byte) adc_val >> 24);
noTone( BUZZER);
tone( BUZZER, 2000, 200); // warn users of the eeprom update
noTone( BUZZER);
tone( BUZZER, 1000, 200);
noTone( BUZZER);
display.clearDisplay();
DisplayStr("OK");
display.display();
delay(500);
}
}
// ---------------------------------------------------------------------------------------------
// substract probe compensation from adc read value
// ---------------------------------------------------------------------------------------------
long real_adc = adc_val - probes_compensation;
if (real_adc<=0) real_adc = 0;
float volts = 2.048 * ((float)(real_adc)/32768); // converts adc reading to volts
// ---------------------------------------------------------------------------------------------
// converts volts reading to resistance using inverse R approximation
// ---------------------------------------------------------------------------------------------
Rx = 0.4595*volts + 0.8165*pow(volts,2) + (-0.595)*pow(volts,3) + 0.2596*pow(volts,4);
// ---------------------------------------------------------------------------------------------
// final adjustment after reading the real value from the probes
// ---------------------------------------------------------------------------------------------
float lcr_measured_res = 1.005; // calibrated using a 1 ohm resistor
float shorty_measured_res = 0.853;
float calibration_factor = lcr_measured_res/shorty_measured_res;
Rx = Rx * calibration_factor;
// ---------------------------------------------------------------------------------------------
// converts resistance to tone frequency 0 (open probes) to 4KHz (shorted probes)
// ---------------------------------------------------------------------------------------------
if (adc_val>32500) {
Rx = 9999;
noTone( BUZZER);
} else {
long adc2 = adc_val/32; // maps 16 bits into 10
// maps adc value to tone frequency from 0 to 4KHz exponential way for better difference in low ohms
float ftone = -386.2467 + (4000 - -386.2467)/(1 + pow(adc2/26.40582,0.6354983));
tone( BUZZER, ftone);
}
// ---------------------------------------------------------------------------------------------
// display resistance value on oled
// ---------------------------------------------------------------------------------------------
display.clearDisplay(); // ... and display result
BatteryIcon((Vbat-6.5)/(9.0-6.5)); // 6.5V = 0%, 9V = 100%
display.setTextSize(3);
display.setTextColor(WHITE);
display.setCursor(0,10);
if (Rx>1000) {
display.print("-----");
noTone( BUZZER);
} else {
display.print(Rx,4);
}
DisplayOmega();
display.display();
}
void BatteryIcon(float charge)
// ---------------------------------------------------------------------------------------------
// Draw a battery charge icon into the display buffer without refreshing the display
// - charge ranges from 0.0 (empty) to 1.0 (full)
// ---------------------------------------------------------------------------------------------
{
int w = constrain(charge, 0.0, 1.0)*16; // 0 to 16 pixels wide depending on charge
if (charge<0) {
w = 0;
}
display.drawRect(100, 0, 16, 7, WHITE); // outline
display.drawRect(116, 2, 3, 3, WHITE); // nib
display.fillRect(100, 0, w, 7, WHITE); // charge indication
}
void DisplayOmega( void)
{
static const unsigned char PROGMEM omega_bmp[] = // omega (ohm) symbol
{ B00000011, B11000000,
B00001111, B11110000,
B00111000, B00011100,
B01100000, B00000110,
B01100000, B00000110,
B11000000, B00000011,
B11000000, B00000011,
B11000000, B00000011,
B11000000, B00000011,
B11000000, B00000011,
B01100000, B00000110,
B01100000, B00000110,
B01100000, B00000110,
B00110000, B00001100,
B11111000, B00011111,
B11111100, B00111111 };
// display omega (ohms) symbol
display.drawBitmap(110, 14, omega_bmp, 16, 16, WHITE);
}
void DisplayStr(char *s)
// ---------------------------------------------------------------------------------------------
// Adds a string, s, to the display buffer without refreshing the display @ (0,20)
// ---------------------------------------------------------------------------------------------
{
display.setTextSize(3);
display.setTextColor(WHITE);
display.setCursor(0,10);
display.print(s);
}
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