Hi
I ran this sample code and it works fine. How can I modify it to use it as a DC voltmeter (and possibly AC voltmeter in the future)?
//https://github.com/aeonSolutions/AeonLabs-ADS1252-24bit-ESP32-Arduino-Library/blob/main/example/ADS1252_Test.ino
#include <SPI.h>
#define MISOPIN 36 //36 //17, pin #5 1252
#define SCLKPIN 35
#define CLKPIN 19 //37 // 37 //20
// calculation formulas:
float f_ADSCLK = 10000000;// 10 MHz
float f_MCLK = f_ADSCLK / 6;
float DRATE = f_MCLK / 64;
float p_MCLK = 1 / f_MCLK;
float t2 = 6 * p_MCLK;
float t3 = 6 * p_MCLK;
float t7 =30;
float DRDY_partition = 36 * p_MCLK;
float DOUT_partition = 348 * p_MCLK;
float CONVCYCLE = DRDY_partition + DOUT_partition; // = 384 * p_MCLK;
float t_RESET_5 = 5 * CONVCYCLE;
void setup(){
Serial.begin(115200);
pinMode(SCLKPIN, OUTPUT);
pinMode(MISOPIN, INPUT);
pinMode(CLKPIN, OUTPUT);
// put ADC on reset at the outset
reset_adc();
// SPI.begin(VSPI_SCLK, VSPI_MISO, VSPI_MOSI, VSPI_SS); //SCLK, MISO, MOSI, SS
SPI.begin(SCLKPIN, MISOPIN, 19, CLKPIN );
SPI.setFrequency(f_ADSCLK);
// initialize SPI (with default settings, including...
// CPOL = 0: so that SCLK is normally LOW
// CPHA = 0: data sampled on rising edge (LOW to HIGH)
// perhaps try changing CPHA ??
digitalWrite(SCLKPIN, LOW);
// release ADC from reset; now we're at a known point
// in the timing diagram, and just have to wait for
// the beginning of a conversion cycle
Serial.println("setup completed");
}
//***************************************
void loop(){
Serial.println("reset adc");
// put ADC on reset at the outset
reset_adc();
Serial.println("reset completed");
long int initTime= millis();
Serial.print("MISO PIN RAW: ");
Serial.println( digitalRead(MISOPIN) );
while( (digitalRead(MISOPIN) != HIGH) && (millis()-initTime < 5000) ){ // 5 sec timeout
Serial.print(millis()-initTime);
Serial.print(" (");
Serial.print( digitalRead(MISOPIN) );
Serial.print(")...");
delay(1000);
}
Serial.println("miso pin probe completed");
if (initTime - millis() >= 5000 ){
Serial.println("Timeout waiting for response");
}
Serial.println("read adc");
read_adc();
digitalWrite(SCLKPIN, LOW);
delay(1000);
}
//************************************************
// to reset ADC, we need SCLK HIGH for min of 4 CONVCYCLES
// so here, hold SCLK HIGH for 5 CONVCYCLEs = 1440 usec
void reset_adc(){
digitalWrite(SCLKPIN, HIGH);
delay(t_RESET_5);
}
// *********************************************
void read_adc(){
// go to drdy_wait routine, where we wait for
// DRDY phase to pass, and thus for DOUT phase to begin
drdy_wait();
byte byte1; byte byte2; byte byte3;
byte flipper = 0b11111111; // 8 bit number to flip bits of a byte
byte addone = 0b1; // to add one to the two's complement
if ( digitalRead(MISOPIN) == HIGH ){
SPI.beginTransaction(SPISettings(f_ADSCLK, MSBFIRST, SPI_MODE0));
digitalWrite(SCLKPIN, LOW);
delay(t2);
delay(t3);
//delay(t7);
byte3 = SPI.transfer(0x00);
byte2 = SPI.transfer(0x00);
byte1 = SPI.transfer(0x00);
}
// read in adc data (sending out don't care bytes)
// and store read data into three bytes */
digitalWrite(SCLKPIN, HIGH);
SPI.endTransaction();
Serial.println(byte1, DEC);
Serial.println(byte2, DEC);
Serial.println(byte3, DEC);
Serial.println();
int check = byte3 << 1;
if (check == 1){
// Negative number in two's complement form. need to flip bytes. and add one to them.
// negative = "-";
// flip the bits
byte3 = byte3^flipper;
byte2 = byte2^flipper;
byte1 = byte1^flipper;
}else{
// negative = "+";
// no need to flip or add one
addone = 0b0;
}
float ads_output =0;
ads_output = 5*(((byte3 << 16) + (byte2 << 8) + (byte1 + addone))) >> 24;
Serial.println(ads_output,10);
//cout << " two's Complement : " << 5*(((byte3 << 16) + (byte2 << 8) + (byte1 + addone))/pow(2,24)) << endl;
// print out data;
// will these instructions eat into time significantly?
// possible improvement: store all data from multiple cycles
// into array, and print out only later at end.
}
//***********************************************
// wait for DRDY to pass and to reach start-point of DOUT
void drdy_wait(){
delay(DRDY_partition);
}
Personally, I'd pick a different A2D. This one has an oddball data interface that's not really SPI. That's why the GitHub code you posted had to jump through hoops to get it to "work" with SPI. Otherwise, you have to bit-bang it. Neither of these choices is very desirable.
