ESP32 Forum

Hi, I have a project where I need more GPIO pins than freely available on the ESP32 and would like to have a second ESP32 managing some sensors and, when requested, send sensor reading to the main ESP32 to be uploaded to the internet via GPRS (no Wifi available).
I would like to avoid using local WiFi or BlueTooth because the device will be powered by batteries.
I have been looking for examples of such ESP32 to ESP32 local communication but found none.
What is the best/fastest way to achieve that?
Assistance will be highly welcome.
Thanks in Advance.
Paulo

Depends on your throughput/latency/aliasing needs.
Typically you have the console/programming serial port (2 pins) available, so would 250Kbps+ soft scheduling do?
If you use the programming link then you would have to disconnect one processor whilst programming the other (unless you do OTA).

If serial speeds will work for you then use serial port 1 on both ESP32's to talk to one another.

If you plan to use default pins I would rather try UART2 (default pins 16/17)

On the boards I use (or maybe for all boards?) the default pins for UART1 are in use for flash memory

I have not tested the speed you can get, but it might be higher than you think

If it is just more GPIO pins that you need, input or output, use an I/O expander chip like the PCF8574, which communicates over I2C. Of course, this won't do if you need high I/O bandwidth, but serves well for low I/O GPIO ports. Put your high bandwidth GPIOs on the ESP32 and allocate low bw on the expander.

https://ecee.colorado.edu/~mcclurel/Phi ... 8574_4.pdf

These are cheap, effective, and simple to code for.

Hi, thanks all.
What I need is to connect a camera to a TTGO Call where most pins are already taken. relocating some functions may be a solution but I would prefer to have an ESP32-Cam sending captured pictures once every, say, 10 minutes. That would solve the problem.
Regards