#include <SPI.h>
#include <SD.h>

#define SD_CS    5
#define SD_SCK   18
#define SD_MISO  19
#define SD_MOSI  23

void testSD() {
  Serial.println("--------------------------------");
  Serial.println("Initializing SPI...");

  SD.end();
  SPI.end();
  delay(500);

  SPI.begin(SD_SCK, SD_MISO, SD_MOSI, SD_CS);

  pinMode(SD_CS, OUTPUT);
  digitalWrite(SD_CS, HIGH);

  delay(2000);   // Give the SD module time to stabilize

  Serial.println("Trying SD.begin() at 25 kHz...");

  if (!SD.begin(SD_CS, SPI, 25000)) {
    Serial.println("***** MOUNT FAILED *****");
    Serial.print("Card Type: ");
    Serial.println(SD.cardType());
    return;
  }

  Serial.println("***** MOUNT SUCCESS *****");

  uint8_t type = SD.cardType();

  Serial.print("Card Type: ");

  switch (type) {
    case CARD_MMC:
      Serial.println("MMC");
      break;
    case CARD_SD:
      Serial.println("SDSC");
      break;
    case CARD_SDHC:
      Serial.println("SDHC");
      break;
    default:
      Serial.println("UNKNOWN");
      break;
  }

  Serial.print("Card Size: ");
  Serial.print(SD.cardSize() / (1024 * 1024));
  Serial.println(" MB");

  File file = SD.open("/test.txt", FILE_WRITE);

  if (file) {
    file.println("ESP32 SPI TEST");
    file.close();
    Serial.println("Write OK");
  } else {
    Serial.println("Write FAILED");
  }
}

void setup() {
  Serial.begin(115200);
  delay(3000);
  Serial.println("===== CONTINUOUS SPI SD TEST =====");
}

void loop() {
  testSD();
  delay(5000);
}