What should I do if the esp32 cam has insufficient pins?

Projects General Guidance
22

This is the scenario of used/unused pins of ESP-WROOM-32 Module when seen togethr with Camera, PSRAM, and SDCard: (Prepaerd consulting the schematic of ESP32-CAM Module, Fig-1.)

ESP2CAMSchematic
ESP2CAMSchematic1261×838 315 KB

Figure-1:

#/GPIO_ESP-WROOM-32_Module  UsedByCAM    UsedByPSRAM   usedBySDCard
1/GND
2/3.3V
3/EN
4/36----------------------------Yes(CAM)
5/39----------------------------Yes(CAM)
6/34----------------------------Yes(CAM)
7/35----------------------------Yes(CAM)
8/32----------------------------Yes(CAM)
9/33--free(driving)onboard_LED   
10/25---------------------------Yes(CAM)
11/26---------------------------Yes(CAM)
12/27---------------------------Yes(CAM)
13/14--(free if SDCard not used)-------------------------Yes
14/12--(free if SDCard not used)-------------------------Yes                  
15/GND
16/13--(free if SDCard not used)-------------------------Yes
17/9------------------------------------Yes(PSRAM)
18/10----------------------------------Yes(PSRAM)
19/11-------free--------------
20/6--------free-------------
21/7------------------------------------Yes(PSRAM)
22/8------------------------------------Yes(PSRAM)
23/15--(free if SDCard ot used)-------------------------------Yes
24/2---(free if SDCard not used)------------------------------Yes
25/0-----------------------------Yes(CAM)
26/4--(free if SDCard and Flash Bulb not used)---------Yes
27/16------------------------------------Yes(PSRAM)
28/17------------------------------------Yes(PSRAM)
29/5-----------------------------Yes(CAM)
30/18---------------------------Yes(CAM)
31/19---------------------------Yes(CAM)
32/NC
33/21--------------------------Yes(CAM)
34/3------free after uploading--
35/1------free after uploading--
36/22------------------------Yes(CAM)
37/23------------------------Yes(CAM)
38/GND

Total free GPIO lines: 11
GPIO-33, 14, 12, 13, 11, 6, 15, 2, 4, 3, 1

image
image1000×445 115 KB

Figure-2:

(Facing Camera) on ESP32-CAM Module -- at right/bottom.

23

Ah so the pin that is connected to EN (Reset) on some ESP32CAM boards, be careful using that pin for other stuff.

24

I thought that GPIO6 and GPIO11 were used by the ESP32 flash memory, maybe my memory is failing ?

25

Right! That pin (righ-bottom and falsely marked as GND) of CAM Board is connected with EN-pin of ESP-WROOM-32 Module (for my CAM Module).

Right! Those GPIO lines (6, 11) of ESP-WROOM-32 Module are indeed connected with off-chip flash memory (Fig-1).
esp32offchipflash
Figure-1:

Ultimately, the ESP32-CAM Module has 8 (+1) free GPIO lines if SDCard/Flash_Bulb and onboard LED are not used.

Practically, it is beyond one's ability to unfold the Metallic box of the ESP-WROOM-32 Module and bring out two free GPIO37 and GPIO38 lines from Pin-6 and 7 of the ESP32 MCU (Fig-2).

esp32PinMappingAmong3
esp32PinMappingAmong31084×872 25.3 KB

Figure-2:

To @srnet, I am extending my humble gratitude for exercising his wise and smart way of bringing me out-of darkness of the statuses of the GPIO lines of the ESP-WROOM-32 Module.

26

Hi srnet,
may i ask if you managed to get your SPI LoRa Device working? Can you share the pins you used?

I am bangig my head against a wall here and tried all kinds of pinout combinations.

The LoRa Device is not faulty, a dummy sender sketch on another ESP32 Wemos D1 Mini is working without any issues.

27

Yes I did, and it took a long while to make the ESP32CAM, SD and LoRa module work;

28

so if we use both sd card slot and all flash and led then what is the total no. of free usable pins that are available on esp32- cam

29

Here is how to free up GPIO12 and GPIO13.
URL: ESP32-CAM AI-Thinker Pinout Guide: GPIOs Usage Explained | Random Nerd Tutorials
Search for "Norberto REDONDO MELCHOR", find post @ March 10, 2020 4:25PM.
Look for bullet point 2.

(I followed this method to successfully configure those pins for I2C and added DS3231/RTC and SSD1306/OLED display to the AiThinker ESP32-CAM)

Here is the snippet:

In order to free pin12 and pin13 (provided you wouldn’t need them for a very demanding SD card usage) you can modify ESP32-CAM fuses like this:

(from Terminal window) $ espefuse.py –baud 115200 –port your_USB_port_name set_flash_voltage 3.3V

and then include in your Arduino code:

SD_MMC.begin(“/sd”, true);

When you set the second initializer attribute to ‘true’ you’re saying that SD card will run in ‘1-line’ mode. This apparently suggests that SD card would continue to be accessible in a slower or less versatile mode, but I have not tested it.

Anyway, after that code line, you can use pins 12 and 13 like any other I/O pin. I’ve done it, and it works.

30

You can use pin 12 without changing fuses, just be sure its left floating during reset.

Pin13 is no needed if the SD card is used in 1bit MMC mode, which is a simple code fix.

31

@srnet: If PIN12 is used as the I2C clock, would it be floating during ESP32 boot-up/reset? IIRC, I had to change the fuse for that to work

32

It would not be floating if you have an I2C pullup resistor on the pin ......