MicroSD Card Module with a Raspberry Pi Pico

// MicroSD Card Module on Raspberry Pi Pico: wiring and a free simulation at https://www.tinkered.ai/components/microsd-module/raspberry-pi-pico
#include <SPI.h>
#include <SD.h>

const int SD_CS = 0;

void setup() {
  Serial.begin(115200);
  if (!SD.begin(SD_CS)) {
    Serial.println("No card, or the wiring is wrong");
    while (1) delay(10);
  }
  File f = SD.open("/LOG.TXT", FILE_WRITE);
  if (f) {
    f.println(millis());
    f.close();
  }
  f = SD.open("/LOG.TXT");
  while (f && f.available()) Serial.write(f.read());
  if (f) f.close();
}

void loop() {}