I have tried all the GPIO pins listed here:This is a schematic of the ESP32 cam pinouts. I have tried every one of the GPIO pins with errors in initializing the SD CardI am following this tutorial to save a picture using the ESP32 cam board. I am trying to add a PIR sensor. https://randomnerdtutorials.com/esp32-cam-take-photo-save-microsd-card/

whenever I try to use any pins to enable wake on external pin high, there is an error either because of interruption with the camera initiation or sd card.

here is my PIR sensor https://www.robotshop.com/en/wide-angle-pir-motion-sensor.html?gclid=EAIaIQobChMI0Y7QuaOA4wIVl_5kCh3zYA4OEAQYASABEgJFPvD_BwEPIR sensor schematic here is the code I am using

      Rui Santos
      Complete project details at https://RandomNerdTutorials.com/esp32-cam-    take-photo-save-microsd-card

       - Select Board "ESP32 Wrover Module"
      - Select the Partion Scheme "Huge APP (3MB No OTA)
    - GPIO 0 must be connected to GND to upload a sketch
    - After connecting GPIO 0 to GND, press the ESP32-CAM on-board RESET  button to put your board in flashing mode

   Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files.
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.

 #include "esp_camera.h"
 #include "esp_timer.h"
 #include "img_converters.h"
 #include "Arduino.h"
 #include "fb_gfx.h"
 #include "fd_forward.h"
 #include "fr_forward.h"
 #include "FS.h"                // SD Card ESP32
 #include "SD_MMC.h"            // SD Card ESP32
 #include "soc/soc.h"           // Disable brownour problems
 #include "soc/rtc_cntl_reg.h"  // Disable brownour problems
 #include "dl_lib.h"
 #include "driver/rtc_io.h"
 #include <EEPROM.h>            // read and write from flash memory 

    // define the number of bytes you want to access
     #define EEPROM_SIZE 1

     // Pin definition for CAMERA_MODEL_AI_THINKER 
     #define PWDN_GPIO_NUM     32
     #define RESET_GPIO_NUM    -1
     #define XCLK_GPIO_NUM      0
     #define SIOD_GPIO_NUM     26
     #define SIOC_GPIO_NUM     27 

     #define Y9_GPIO_NUM       35
     #define Y8_GPIO_NUM       34
     #define Y7_GPIO_NUM       39
     #define Y6_GPIO_NUM       36
     #define Y5_GPIO_NUM       21
     #define Y4_GPIO_NUM       19
     #define Y3_GPIO_NUM       18
     #define Y2_GPIO_NUM        5
     #define VSYNC_GPIO_NUM    25
     #define HREF_GPIO_NUM     23
     #define PCLK_GPIO_NUM     22

     int pictureNumber = 0;

     void setup() {
       WRITE_PERI_REG(RTC_CNTL_BROWN_OUT_REG, 0); //disable brownout detector


       camera_config_t config;
       config.ledc_channel = LEDC_CHANNEL_0;
       config.ledc_timer = LEDC_TIMER_0;
       config.pin_d0 = Y2_GPIO_NUM;
       config.pin_d1 = Y3_GPIO_NUM;
       config.pin_d2 = Y4_GPIO_NUM;
       config.pin_d3 = Y5_GPIO_NUM;
       config.pin_d4 = Y6_GPIO_NUM;
       config.pin_d5 = Y7_GPIO_NUM;
       config.pin_d6 = Y8_GPIO_NUM;
       config.pin_d7 = Y9_GPIO_NUM;
       config.pin_xclk = XCLK_GPIO_NUM;
       config.pin_pclk = PCLK_GPIO_NUM;
       config.pin_vsync = VSYNC_GPIO_NUM;
       config.pin_href = HREF_GPIO_NUM;
       config.pin_sscb_sda = SIOD_GPIO_NUM;
       config.pin_sscb_scl = SIOC_GPIO_NUM;
       config.pin_pwdn = PWDN_GPIO_NUM;
       config.pin_reset = RESET_GPIO_NUM;
       config.xclk_freq_hz = 20000000;
       config.pixel_format = PIXFORMAT_JPEG; 

        config.jpeg_quality = 10;
        config.fb_count = 2;
      } else {
        config.frame_size = FRAMESIZE_SVGA;
        config.jpeg_quality = 12;
        config.fb_count = 1;

      // Init Camera
      esp_err_t err = esp_camera_init(&config);
      if (err != ESP_OK) {
        Serial.printf("Camera init failed with error 0x%x", err);

      //Serial.println("Starting SD Card");
        Serial.println("SD Card Mount Failed");

      uint8_t cardType = SD_MMC.cardType();
      if(cardType == CARD_NONE){
        Serial.println("No SD Card attached");

      camera_fb_t * fb = NULL;

      // Take Picture with Camera
      fb = esp_camera_fb_get();  
      if(!fb) {
        Serial.println("Camera capture failed");
      // initialize EEPROM with predefined size
      pictureNumber = EEPROM.read(0) + 1;

      // Path where new picture will be saved in SD Card
      String path = "/picture" + String(pictureNumber) +".jpg";

      fs::FS &fs = SD_MMC; 
      Serial.printf("Picture file name: %s\n", path.c_str());

      File file = fs.open(path.c_str(), FILE_WRITE);
        Serial.println("Failed to open file in writing mode");
      else {
        file.write(fb->buf, fb->len); // payload (image), payload length
        Serial.printf("Saved file to path: %s\n", path.c_str());
        EEPROM.write(0, pictureNumber);

      // Turns off the ESP32-CAM white on-board LED (flash) connected to GPIO 4
      pinMode(4, OUTPUT);
      digitalWrite(4, LOW);

      Serial.println("Going to sleep now");
      Serial.println("This will never be printed");

    void loop() {


This is the thing I am trying to add. but no matter which pins i chose there are errors. I can add the error if that would be helpful.

esp_sleep_enable_ext0_wakeup(GPIO_NUM_X, level)
  • A schematic of how you are hooking up the PIR to the esp32 cam board would help.
    – st2000
    Commented Jun 23, 2019 at 13:42
  • @st2000 I added some more info to the OP. Commented Jun 23, 2019 at 13:48
  • So, you are using pins other than pin 3 (E32_RST)? Guessing, most embedded processors generate different vectors (places they go to and start code execution) based on which pins are generating interrupts. It may be that the libraries you are using only setup an interrupt for pin 3. As this is all guess work - I'm resisting the temptation to change this comment into an answer.
    – st2000
    Commented Jun 23, 2019 at 15:36
  • I am not seeing a pin 3 (esp32 rst) on this board. Could you point it out. Then you can change this to can answer. Commented Jun 23, 2019 at 16:21
  • I am looking at this schematic. Assuming this is the board you have. I see a reset switch connected to net ES32_RST. Which appears at pin 3 of the ESP-32S chip. Guessing, if your PIR uses an open collector to ground type output, you might try soldering to the open side of the reset switch.
    – st2000
    Commented Jun 23, 2019 at 17:14

1 Answer 1



It may be that one of the included libraries (software) you are using depends on pin 3 (E32_RST) of the ESP32 going low in order to operate as expected (wake up and take a picture). Using an alternate pin may wake up the ESP32 but may not behave as expected.


This schematic of the ESP32 Camera shows how switch K1 is connected to pin 3 of the ESP32. There is a capacitor C7 and resistor R6 likely used to mitigate K1 switch bouncing and to pull pin 3 high when switch K1 is not pressed. When switch K1 is pushed it pulls pin 3 to ground waking up the ESP32 to take a picture.

The PIR specified changes its output to high when activated according to its data sheet. This is opposite of what the ESP32 needs to see at pin 3 in order to take a picture. It appears an inverter is needed between the PIR and pin 3 of the ESP32. An open collector type of inverter would be best as this type of driving circuit can be attached where K1, C7 & R6 come together with out interfering with the their (the existing components') operation. This is the subject of this stackexchange question / answer.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.