ESP32-CAM can't upload new IDE sketch after an sd initialization.. SPI&SD keep MISO level HIGH

The ESP32-CAM has a SD-micro slot on the main board. and is mounted on a ESP32-CAM-MB board for providing serial communication. (eg https://universal-solder.ca/wp-content/uploads/2021/03/5083_b61d93cb-2cb4-4503-b537-ca77679cc7ad0.jpg)

The SD is blocking a new reload of a Sketch after the SD-micro has been initialized.

After the following commands the board can't reload a new IDE sketch

  SPI.begin(14, 2, 15, 13);
  if (!SD.begin(13) ) {
    Serial.println("initialization failed!");
    while (1);
  }

Pressing the reset-button of the ESP32-CAM board does not solve the issue as the SD-micro card still blocks a new sketch upload. The only way to reload a new sketch is to remove the SD-micro (basically a power down) after which the MISO signal of the SD card is disabled (high impedance again).....

/*
 *  Device: Ai-Thinker ESP32-CAM
 *  
 *  Schematic SD connections
 * 1  DATA2      HS2DATA2  GPIO12   x
 * 2  CD/DATA3   HS2DATA3  GPIO13   CS    CS
 * 3  CMD        HS2CMD    GPIO15   DI    MOSI
 * 4  3.3v
 * 5  CLK        HS@CLK    GPIO14   SCLK  SCLK
 * 6  GND
 * 7  DATA0      HS2DATA0  GPIO02   DO    MISO
 * 8  DATA1                         x
 * 
 * HS2DATA1I.begin(14, 2, 15, 13);
 * Reboot code
 *  x1 GPIO  5 
 *  x2 GPIO 15 MTDO
 *  x4 GPIO  4
 *  x8 GPIO  2
 *  1x GPIO  0
 *  2x GPIO 12 MTDI
 * 
 * Problem: Can't upload Arduino IDE sketch after First run of initialization of the SD card
*/
#include <SPI.h>
#include <SD.h>
File root;
#define ONBOARD_LED 33    // main board red LED
#define FLASHLIGHT_LED 4  // Main board White LED

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(115200);
  while (!Serial) {
    ;  // wait for serial port to connect. Needed for native USB port only
  }
  pinMode(ONBOARD_LED, OUTPUT);     // THE LED GOES OFF AFTER WRITING TO HIGH
  pinMode(FLASHLIGHT_LED, OUTPUT);  // THE LED GOES OFF AFTER WRITING TO LOW
  SetupBySPI_SD();
}

void loop() {
  // nothing happens after setup finishes.
  digitalWrite(ONBOARD_LED, !digitalRead(ONBOARD_LED));  // turn the LED off by making the voltage LOW
  delay(100);
}

void SetupBySPI_SD() {
  //https://openlabpro.com/guide/interfacing-microcontrollers-with-sd-card/
  Serial.print("Initializing SD card...");
  // Master Out, Slave In (MOSI) - which is the data going OUT (send) from the master esp32-cam  to the sd-slave
  // Master In, Slave Out (MISO) - which is the data going OUT (send) from the sd-slave into the master
  // SPI.begin(SCK,MISO,MOSI,CS);  ==> (sclk,d0,di,cs)
  SPI.begin(14, 2, 15, 13);
  if (!SD.begin(13)) {
    Serial.println("initialization failed!");
    while (1)
      ;
  }
  Serial.println("initialization by SPI.begin(14, 2, 15, 13) done.");
  root = SD.open("/");
  printDirectory(root, 0);
  Serial.println("done!");
  Serial.println("SPI Terminating.");

  // Lets try to disable the SD again by stopping the SD & SPI
  SD.end();
  SPI.end();

  // Disable the SD by an HIGH CS
  pinMode(13, OUTPUT);
  digitalWrite(13, HIGH);
  Serial.print("PIN13 : ");
  Serial.println(digitalRead(13));

  // This goes wrong !!!! Signal stays HIGH !!!!!!!
  pinMode(2, OUTPUT);
  digitalWrite(2, LOW);
  //This means that MISO of the SD-micro is not released
  //Lets make it easier to check with my scope.
  //The output will be pulled down at the moment MISO is released from the SD-micro
  pinMode(2, INPUT_PULLDOWN);
  Serial.print("PIN2 : ");
  Serial.println(digitalRead(2));

  // we need a number (>4) of extra clock pulses after CS was disabled before MISO is released !!!!!
  pinMode(14, OUTPUT);
  digitalWrite(14, LOW);
  Serial.print("PIN14 : ");
  Serial.println(digitalRead(14));
  pinMode(14, OUTPUT);
  digitalWrite(14, HIGH);
  pinMode(14, OUTPUT);
  digitalWrite(14, LOW);
  pinMode(14, OUTPUT);
  digitalWrite(14, HIGH);
  pinMode(14, OUTPUT);
  digitalWrite(14, LOW);
  pinMode(14, OUTPUT);
  digitalWrite(14, HIGH);
  pinMode(14, OUTPUT);
  digitalWrite(14, LOW);
  pinMode(14, OUTPUT);
  digitalWrite(14, HIGH);
  pinMode(14, INPUT_PULLUP);

  // If the SD and SPI application would run correct, the signal should go LOW !!!!!!!
  // If the SD-micro is not detached correctly, MISO will stay HIGH!!!
  pinMode(2, OUTPUT);
  digitalWrite(2, LOW);  //Check if you can set 0. If s0, leave the signal as input
  pinMode(2, INPUT_PULLDOWN);
  Serial.print("PIN2 : ");
  Serial.println(digitalRead(2));
  pinMode(15, OUTPUT);
  digitalWrite(15, LOW);
  Serial.print("PIN15 : ");
  Serial.println(digitalRead(15));

  // Easy method to reboot again
  // ESP.restart();
}

void printDirectory(File dir, int numTabs) {
  while (true) {
    File entry = dir.openNextFile();
    if (!entry) {
      // no more files
      Serial.println("Close Print directory");
      break;
    }
    for (uint8_t i = 0; i < numTabs; i++) {
      Serial.print('\t');
    }
    Serial.print(entry.name());
    if (entry.isDirectory()) {
      Serial.println("/");
      printDirectory(entry, numTabs + 1);
    } else {
      // files have sizes, directories do not
      Serial.print("\t\t");
      Serial.println(entry.size(), DEC);
    }
    entry.close();
  }
}

arduino-libraries / SD

ESP32-CAM can't upload new IDE sketch after an sd initialization.. SPI&SD keep MISO level HIGH #111