Hello everyone,
I am trying to setup an Arduino with SPI to an AD7787 for testing before I use it in my project. I cannot get a valid data response from it, though. I am hoping for some assistance —many thanks for considering my request. AD7787
I have a DAC plugged into the AIN2 channel of the AD7787, and the DAC output is steadily decreasing over 1.3 seconds. I have confirmed the dac output via a scope. The DAC is also on the SPI bus.
My transaction looks like this:
Begin transaction
Write CS low
Send 0x11 (Select mode register, channel AIN2)
Send 0x84 (Request single conversion, unipolar mode, unbuffered)
Wait for dReady pin to read zero
Send 0x39 (Select the data register, read, channel AIN2)
Read byte
Read byte
Read byte
Write CS high
End transaction
Is my communication incorrect?
I have posted the code I'm using as well.
//INO*****************************************
#include "AD7787.h"
#include "AD5664.h"
#include <SPI.h>
#define ad7787CSPin 9
AD7787 ad7787;
#define ad5664CSpin 10
AD5664 ad5664;
// the setup function runs once when you press reset or power the board
void setup()
{
pinMode(ad7787CSPin, OUTPUT);
pinMode(ad5664CSpin, OUTPUT);
pinMode(27, INPUT);//MISO Reading pin
digitalWriteFast(ad7787CSPin, HIGH);
digitalWriteFast(ad5664CSpin, HIGH);
Serial.begin(9600);
SPI.begin();
while (!Serial) {}
Serial.printf("It begins\r\n");
ad5664.initializeSPI(4000000, ad5664CSpin);
ad5664.reset();
ad7787.initializeSPI(5500000, ad7787CSPin);
ad7787.reset();
delay(500);
}
// the loop function runs over and over again until power down or reset
void loop()
{
uint32_t reply = 0;
uint16_t dacValue = 0;
ad5664.setDAC(0, dacValue);
delay(130);
for (int index = 0; index < 10; index++)
{
Serial.printf("DAC> %u\r\n", dacValue);
reply = ad7787.singleConversion();
Serial.printf("Data received> %u\r\n", reply);
dacValue += 6550;
ad5664.setDAC(0, dacValue);
delay(130);
}
delay(2000);
}
//AD7787 ******************************************************
#include "AD7787.h"
AD7787::AD7787()
{
return;
}
void AD7787::initializeSPI(int speed, int cs)
{
pSettings = new SPISettings(speed, MSBFIRST, SPI_MODE3);
pinCS = cs;
return;
}
uint32_t AD7787::singleConversion()
{
uint32_t result = 0;
bool adcRunning = true;
SPI.beginTransaction(*pSettings);
digitalWriteFast(pinCS, LOW);//SS low
char buff[2] = { (MODE_R | 1), (SnCONv | UNIPOLAR | UBUFMODE) };
SPI.transfer(buff[0]);//CR: MR //h11
SPI.transfer(buff[1]);//MR: Single Conv, unipolar, unbuffered //h84
while (adcRunning)
{
if (digitalReadFast(27) == 0)
{ adcRunning = false; }
}
//Read out the data
SPI.transfer((3 << 4) | (1 << 3) | 1);//Access data reg //h39
result = readData();
digitalWriteFast(pinCS, HIGH);//SS high
SPI.endTransaction();
return result;
}
uint32_t AD7787::readData()
{
uint32_t adcResult = 0;
uint8_t receivedBytes[3] = { 0 };
receivedBytes[0] = SPI.transfer(0x0);
adcResult |= receivedBytes[0];
adcResult = adcResult << 8;
receivedBytes[1] = SPI.transfer(0x0);
adcResult |= receivedBytes[1];
adcResult = adcResult << 8;
receivedBytes[2] = SPI.transfer(0x0);
adcResult |= receivedBytes[2];
Serial.printf("Bytes> 1: %u, 2: %u, 3: %u\r\n", receivedBytes[0], receivedBytes[1], receivedBytes[2]);
return adcResult;
}
void AD7787::reset()
{
SPI.beginTransaction(*pSettings);
digitalWriteFast(pinCS, LOW);
SPI.transfer(0xFF);
SPI.transfer(0xFF);
SPI.transfer(0xFF);
SPI.transfer(0xFF);
digitalWriteFast(pinCS, HIGH);
SPI.endTransaction();
return;
}
The response I am getting from running it.
DAC> 0 Bytes> 1: 64, 2: 43, 3: 243 Data received> 4205555 DAC> 6550 Bytes> 1: 121, 2: 221, 3: 38 Data received> 7986470 DAC> 13100 Bytes> 1: 121, 2: 221, 3: 4 Data received> 7986436 DAC> 19650 Bytes> 1: 121, 2: 220, 3: 195 Data received> 7986371 DAC> 26200 Bytes> 1: 121, 2: 221, 3: 201 Data received> 7986633 DAC> 32750 Bytes> 1: 121, 2: 219, 3: 251 Data received> 7986171 DAC> 39300 Bytes> 1: 121, 2: 222, 3: 3 Data received> 7986691 DAC> 45850 Bytes> 1: 121, 2: 221, 3: 117 Data received> 7986549 DAC> 52400 Bytes> 1: 121, 2: 220, 3: 235 Data received> 7986411 DAC> 58950 Bytes> 1: 121, 2: 221, 3: 72 Data received> 7986504
Any help is greatly appreciated. Thank you.
Changed SPI mode to 3
[edited by: Zip at 11:02 PM (GMT -4) on 19 Apr 2023]
