Hi,
I am merge few sketches into a multi-sketch with few tabs, questions here need help please:
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what function should not put into class, such as ISR ?
-
the project designed with Arduino UNO, there are not enough pins for added items, replaced by MEGA2560, seems the ADC totally different? how to modify this? If put some functions at main sketch, how make it relative to its original sketch?
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use NANO may be better?
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There are 2 internal clamping diodes on the I/O pins in Arduion, does MEGA2560 has it?
Thanks
Adam
#include <LiquidCrystal.h> // include Arduino LCD library
// LCD module connections (RS, E, D4, D5, D6, D7)
LiquidCrystal lcd(8, 9, 10, 11, 12, 13);
// define autoranging channel pins
#define CH0 2
#define CH1 3
#define CH2 4
#define CH3 5
const uint16_t Time_Out = 50000, // time out in microseconds
Periods = 10; // number of periods of measurement (for AC voltage only)
// variables
byte ch_number;
const uint16_t res_table[4] = {2444, 244, 94, 47}, // voltage divider resistances in tenths kOhms
total_res = 22444; // total resistance in tenths kOhms
uint16_t current_res;
volatile byte per;
void setup(void)
{
pinMode(CH0, OUTPUT);
pinMode(CH1, OUTPUT);
pinMode(CH2, OUTPUT);
pinMode(CH3, OUTPUT);
lcd.begin(16, 2); // set up the LCD's number of columns and rows
lcd.setCursor(1, 0);
lcd.print("Voltage:");
ch_number = 0;
ch_select(ch_number);
// ADC and analog comparator configuration
ADMUX = 0x03;
ADCSRA = 0x87;
ADCSRB = (0 << ACME); // select AIN1 as comparator negative input
ACSR = 0x13; // turn on analog comparator
}
// analog comparator ISR
ISR (ANALOG_COMP_vect)
{
byte count = 0;
for (byte i = 0; i < 50; i++) {
if ( ACSR & 0x20 )
count++;
}
if (count > 48)
per++;
}
// main loop
void loop()
{
bool dc_flag = 0; // DC voltage flag bit
int32_t sum = 0; // sum of all readings
uint16_t n = 0; // number of readings (samples)
ACSR = (1 << ACI); // clear analog comparator interrupt flag
ACSR = (1 << ACIE); // enable analog comparator interrupt
uint32_t current_m = micros(); // save current millis
byte current_per = per; // save current period number
while ( (current_per == per) && (micros() - current_m < Time_Out) ) ;
if ( micros() - current_m >= Time_Out ) { // if there's time out event ==> voltage signal is DC
dc_flag = 1;
for (byte i = 0; i < 200; i++) {
ADCSRA |= 1 << ADSC; // start conversion
while (ADCSRA & 0x40); // wait for conversion complete
int16_t an = (int16_t)(ADCL | (uint16_t)ADCH << 8) - 511;
sum += an;
n++; // increment number of readings
delay(1);
}
}
else { // here, voltage signal is AC
current_m = micros(); // save current millis()
per = 0;
while ( (per < Periods) && (micros() - current_m < (uint32_t)Time_Out * Periods) ) {
ADCSRA |= 1 << ADSC; // start conversion
while (ADCSRA & 0x40); // wait for conversion complete
int32_t an = (int16_t)(ADCL | (uint16_t)ADCH << 8) - 511;
sum += sq(an); // sq: square
n++; // increment number of readings
}
}
ACSR = (0 << ACIE); // disable analog comparator interrupt
uint32_t total_time = micros() - current_m; // used to claculate frequency
// voltage calculation
float v;
if (dc_flag) // if voltage signal is DC
v = (4 * sum) / n; // calculate Arduino analog channel DC voltage in milli-Volts
else // here voltage signal is AC
v = 4 * sqrt(sum / n); // calculate Arduino analog channel RMS voltage in milli-Volts
// claculate actual (input) voltage in milli-Volts (apply voltage divider equation)
v = v * (float)total_res / current_res;
v /= 1000; // get voltage in Volts
uint16_t v_abs = abs(int16_t(v));
if ( (v_abs >= 10 && ch_number == 0) || (v_abs >= 100 && ch_number == 1) || (v_abs >= 250 && ch_number == 2) ) {
ch_number++;
ch_select(ch_number);
delay(10);
return;
}
if ( (v_abs < 220 && ch_number == 3) || (v_abs < 80 && ch_number == 2) || (v_abs < 8 && ch_number == 1) ) {
ch_number--;
ch_select(ch_number);
delay(10);
return;
}
char _buffer[8];
lcd.setCursor(0, 1);
if ( v < 0)
lcd.print('-');
else
lcd.print(' ');
if (v_abs < 10)
sprintf( _buffer, "%01u.%02u", v_abs, abs((int16_t)(v * 100)) % 100 );
else if ( v_abs < 100)
sprintf( _buffer, "%02u.%01u", v_abs, abs((int16_t)(v * 10)) % 10 );
else
sprintf( _buffer, "%03u ", v_abs );
lcd.print(_buffer);
if (dc_flag)
lcd.print("VDC ");
else {
lcd.print("VAC ");
// calculate signal frequency in Hz
uint32_t period_time = total_time / Periods;
float freq = 1000000.0 / period_time;
sprintf( _buffer, "%02u.%02uHz", (uint16_t)freq % 100, (uint16_t)(freq * 100) % 100 );
lcd.print(_buffer);
}
delay(500); // wait half a second
}
void ch_select(byte n) {
switch (n) {
case 0:
digitalWrite(CH0, HIGH);
digitalWrite(CH1, LOW);
digitalWrite(CH2, LOW);
digitalWrite(CH3, LOW);
break;
case 1:
digitalWrite(CH0, LOW);
digitalWrite(CH1, HIGH);
digitalWrite(CH2, LOW);
digitalWrite(CH3, LOW);
break;
case 2:
digitalWrite(CH0, LOW);
digitalWrite(CH1, LOW);
digitalWrite(CH2, HIGH);
digitalWrite(CH3, LOW);
break;
case 3:
digitalWrite(CH0, LOW);
digitalWrite(CH1, LOW);
digitalWrite(CH2, LOW);
digitalWrite(CH3, HIGH);
}
current_res = res_table[n];
}
