SD Card Reader on Monitor One

Hardware
1

Happy Friday, I am trying to record microphone data from a Max4466 onto an Adafruit ADA254 break out board. After a few hours reading post, Chat GPT, and documentation I finally had code that wasn't failing. However, I am still not creating any files on the 32GB SD card. I am using SdFat 1.1.0 which should be supported on the monitor one Tsom. Here is how I have it wired.

IMG_4923
IMG_49231920×2560 487 KB

And here is the code I am using.

#include "Particle.h"
#include "SdFat.h"

SYSTEM_MODE(SEMI_AUTOMATIC);
SYSTEM_THREAD(ENABLED);

constexpr int CS_PIN = D2;   // moved CS to D2

SdFat SD;
SdFile testFile;

void setup() {
  Serial.begin(9600);
  waitFor(Serial.isConnected, 10*1000);

  Serial.print("Init SD… ");
  // try hardware SPI on D4–D6, CS on D2
  if (!SD.begin(CS_PIN, SD_SCK_MHZ(10))) {
    Serial.println("❌ failed");
    return;
  }
  Serial.println("✅ OK");

  // write a little file
  if (!testFile.open("test.txt", O_WRITE | O_CREAT | O_TRUNC)) {
    Serial.println("❌ open for write failed");
    return;
  }
  testFile.println("hello microSD");
  testFile.close();
  Serial.println("✅ wrote file");

  // read it back
  if (!testFile.open("test.txt", O_READ)) {
    Serial.println("❌ open for read failed");
    return;
  }
  Serial.print("Contents: ");
  while (testFile.available()) {
    Serial.write(testFile.read());
  }
  Serial.println();
  testFile.close();
}

void loop() {
  // nothing else
}```

Any suggestions?
2

D2 (A2) is the external user button. You can't reuse that pin as the SPI CS pin.

3

Bam, I moved it back to A7 and figured out I have the DI and DO wires swapped. It is now working. Thanks again.

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