i have been using “PC Scope” to 'scope some simple OpAmp/Oscillator circuits but now intend to measure some power adaptors which provide 5V at 2A.
FYI; it uses code running on an Arduino;
/*
EFY PC OsciloScope
Read A0 and send to UART at 115200.
Read the voltages as fast as possible and send to serial port.
115200 baud pushes each byte at around 85us.
But the default ADC config by Arduino gives ADC at 116us. so here ADC config with additional lines of code and get samples faster than 85us.
Data throughput is decided by the serial baud rate
@ 115.2k baud we can get 12kSps
Created on 18th Oct 2016
by Balaji ramalingam, Robert Bosch, Banagalore
Balajir@in.bosch.com
*/
// These constants won't change. They're used to give names
// to the pins used:
const int analogInPin1 = A0; // Analog input pin that the potentiometer is attached to
static int ctr,flag_tog;
static unsigned char adcval;
void setup()
{
Serial.begin(115200);
pinMode(13, OUTPUT);
ADCSRA = 0; // clear ADCSRA register
ADCSRB = 0; // clear ADCSRB register
ADMUX |= (0 & 0x07); // set A0 analog input pin
ADMUX |= (1 << REFS0); // set reference voltage
ADMUX |= (1 << ADLAR); // left align ADC value to 8 bits from ADCH register
// sampling rate is [ADC clock] / [prescaler] / [conversion clock cycles]
// for Arduino Uno ADC clock is 16 MHz and a conversion takes 13 clock cycles
//ADCSRA |= (1 << ADPS2) | (1 << ADPS0); // 32 prescaler for 38.5 KHz
ADCSRA |= (1 << ADPS2); // 16 prescaler for 76.9 KHz
//ADCSRA |= (1 << ADPS1) | (1 << ADPS0); // 8 prescaler for 153.8 KHz
ADCSRA |= (1 << ADATE); // enable auto trigger
ADCSRA |= (1 << ADIE); // enable interrupts when measurement complete
ADCSRA |= (1 << ADEN); // enable ADC
ADCSRA |= (1 << ADSC); // start ADC measurements
}
ISR(ADC_vect)
{
adcval = ADCH; // read 8 bit value from ADC
}
void loop()
{
Serial.write(adcval);
// Following code to generate ref signal at pin 13 @ 50HZ. You can connect A0 to see the waveform in PCScope.exe
ctr++;
if(ctr>117) //117=10.03ms
{
ctr=0;
flag_tog = !flag_tog;
digitalWrite(13, flag_tog);
}
}
and the circuit looks like this;
*without the voltage divider which i added to the original suggested circuit by ‘PC Scope’.
now, i am thinking that this 2A is a no-no to plug into the Arduino Uno, right ?
if so, is there some modification i can do to allow measuring of this 2A power supply - something like a current-limiting resistor perhaps ?
