ADS1298: Trouble with SPI communication

Hello Abdelrahman,

Thank you for your post. Can you share a logic analyzer capture of the SPI frame which reads the Device ID register? 

Regards,

Ryan

ADS129X_File.zip

Dear Ryan,

Thank you for your quick response. I have attached a ZIP file that includes the code, along with a snippet from the logic analyser for your reference.

In my code, I am utilizing HSPI commands since I'm working with the HSPI pins on the ESP32. I would greatly appreciate it if you could review the attached files and provide further guidance on the issue.

Best,
Abdelrahman

Hi Ryan, 

I adjusted the SPI configuration and now the SCLK when the nCS is low. Additionally, I am able to send commands with MOSI but there is no activity on MISO. I uploaded a zip folder from the images of the logic analyser + the code. I would appreciate if you can provide me with further guidance. 

#include <SPI.h>

// Define the SPI pins for HSPI (on ESP32 or custom setup)
#define HSPI_MISO   12
#define HSPI_MOSI   13
#define HSPI_SCLK   14
#define HSPI_SS     15
#define PWDN_PIN    32  // Define the PWDN control pin for ADS1298

static const int spiClk = 150000; // 150 kHz clock speed

// Uninitialized pointer to SPI object
SPIClass *hspi = NULL;

void setup() {
  // Initialize serial for debugging
  Serial.begin(115200);
  
  // Initialize instance of the SPIClass attached to HSPI
  hspi = new SPIClass(HSPI);

  // Initialize SPI bus with default pins SCLK = 14, MISO = 12, MOSI = 13, SS = 15
  hspi->begin(HSPI_SCLK, HSPI_MISO, HSPI_MOSI, HSPI_SS);

  // Set SS as output and set it high to start with (deselect)
  pinMode(HSPI_SS, OUTPUT);
  digitalWrite(HSPI_SS, HIGH);

  // Set up the PWDN control pin
  pinMode(PWDN_PIN, OUTPUT);

  // Power up the ADS1298 by setting PWDN pin HIGH
  digitalWrite(PWDN_PIN, HIGH);
  delay(100);  // Small delay to ensure the device powers up

  Serial.println("ADS1298 Powered Up");
}

void loop() {
  // Optionally: Add logic to enter Power-Down mode (if needed)
  // digitalWrite(PWDN_PIN, LOW);  // Pull LOW to enter Power-Down mode
  // delay(1000);  // Delay to simulate Power-Down mode

  byte commands[] = {0x0A, 0x20, 0x00};  // Array of commands
  byte response;                         // Variable to hold the response from the slave
  byte deviceID = 0x00;                  // Device ID

  // Start SPI transaction for sending the commands
  hspi->beginTransaction(SPISettings(spiClk, MSBFIRST, SPI_MODE1));

  // Pull SS low to select the slave
  digitalWrite(HSPI_SS, LOW);
  delayMicroseconds(10);  // Small delay to stabilize the signal
  
  // Send the command bytes to the slave
  for (int i = 0; i < sizeof(commands) / sizeof(commands[0]); i++) {
    response = hspi->transfer(commands[i]);  // Send and receive at the same time
    Serial.print("Sent command: ");
    Serial.println(commands[i], HEX);
    Serial.print("Response from slave: ");
    Serial.println(response, HEX);  // Display the response (if the slave sends any data back)
  }

  // Send and receive device ID
  response = hspi->transfer(deviceID);  // Send and receive at the same time
  Serial.print("Sent device ID command: ");
  Serial.println(deviceID, HEX);
  
  Serial.print("Response from slave: ");
  Serial.println(response, HEX);  // Display the response (if the slave sends any data back)

  // Pull SS high to deselect the slave
  digitalWrite(HSPI_SS, HIGH);

  // End SPI transaction
  hspi->endTransaction();

  delay(1000); // Wait for a second before the next loop
}

Hi Abdelrahman,

In this frame, you are sending the STOP command 0Ah. However, this is only used to stop ADC conversions. That explains why there is no nDRDY or DOUT activity while you send additional SCLKs for the RREG command that follows.

By the way - in order to send the RREG command 0x20 0x00, you must first send SDATAC (11h) (i.e. "stop RDATAC"). This is not the same as the STOP command (0Ah), which is only to control ADC conversions. Understandably this may have caused some confusion. 

Regards,

Ryan