@devan You could use a PaHub to multiplex the three addresses.

@mchott ESP_NOW in peer to peer mode.
I wrote this simple bare-bones application to share with other makers.
https://github.com/teastainGit/ESP_NOWpeer2peer
I have a Core Basic communicating with two M5Stamps in the same room, controlling space heaters and an HVAC vent damper position. etc.
The github example is used in all three devices

@arno The built-in SPI would provide the fastest frame rate but trickier to access the SPI on the Core2, second choice is the built-in I2C interface accessible by the standard Grove port on the left side.
The Core2 is bereft of GPIO as a nod to WiFi BLE I2C ESP_NOW, etc, whereas the foundational Core Basic is better equipped with I/O options!!!
I think M5Stack announced recently a GPIO base to convert the Core2.
I have a Core2 running a simulated nixie-tube clock and two Core Basics.
https://shop.m5stack.com/collections/m5stack-new-arrival/products/extension-port-module-for-core2?variant=43165402398977

Extension Port Module for Core2
SKU: M123 Regular price$6.95 Out Of Stock

@teastain SOLVED!
On one hand it did work for several years with ""esp_now_peer_info_t peerInfo;" placed in the void setup() !!!
After the Board definition, somewhow changed, the project just stopped communicating.
Researching every line of my program revealed that it should have been before the setup() as a declaration.
Whew, my desktop application is back on line!

@marelli7 When I got the StampIO with STM I was disappointed that each chip could only be used in one mode, "All Pin Mode". user felmue made a brilliant but astonishingly simple edit to the actual M5Stack StampIO library which was approved by M5Stack. It allows each pin to be a different mode, such as Pin1 Input, Pin2 Output, etc.
https://imgur.com/EduKPmV

#include <M5Stack.h>
#include <M5_EXTIO2.h>
M5_EXTIO2 extio;
void setup() {
M5.begin();
while (!extio.begin(&Wire, 21, 22, 0x45)) {
Serial.println("extio Connect Error");
delay(100);
}
extio.setPinMode(1, RGB_LED_MODE);
extio.setPinMode(0, DIGITAL_OUTPUT_MODE);
}

void loop() {
extio.setLEDColor(1, 0x0f << (8)); //RGB sk6812 type
delay(1000);
extio.setLEDColor(1, 0x0f << (16));
extio.setDigitalOutput(0, HIGH); // standard mini LED with resistor
delay(1000);
extio.setDigitalOutput(0, LOW);
delay(1000);
}

Otherwise, sorry, I don't have any Encoder code!
Neat profile picture, tho' !

@marelli7 Hi! Just curious if you have the EXT.IO (Pno. U011 using the PCA9554PW chip) or the newer EXT.IO-2 (Pno. U011-B using the STM32F030 chip) ?
Obviously the chips are different! But is would be easy to confuse.
I have the Stamp IO with the STM chip and am familiar with only that one.
Just trying to help!

Hi, all! I use a M5Stack Core Basic to communicate with two M5Stamp boards, in an HVAC app in my home office. (Using the latest Arduino ver 1.8.19) They all worked perfectly together as a stable solution...however...I had updated all my libraries as available. I wanted to edit a screen text and when I uploaded, the source compiled no problems, but the serial error message was "Failed to add peer" and "Error sending the data". (text messages in my code that I put there last year.

I had used the official M5Stack board def, so I tried the older ES32 Arduino folder, M5Stack-Core-RSP32, which USED to do the trick. Still no comm and I tried to revert the Board definitions and no joy.
My basic ESP NOW template is here: https://github.com/teastainGit/ESP_NOWpeer2peer/blob/main/ESPpeer2peer.ino
I put this code into two StickCPlus, with corrected MAC and it used to work. Push the big button on one and the LED on the other comes on, and the same the other way.
I am stuck and need help! Thanks, Terry

@kombistack
oooF! Sorry, I am not familiar with UIflow!!!
Cheers!

Having some fun today running the shortest possible sketches to see how fast they can execute code complied from Arduino IDE. The idea was to turn a physical output on and off as fast as possible!
void loop() {
state = !state;
digitalWrite (OutPin, state);
}
I measured a Core Basic, StickCPLUS and a Stamp-PICO all the same at a minimum of "about" 275 nanoseconds (plus "about" 50ns jitter) per state change or about 550ns for a complete square wave. That's just under 2MHz!
(https://imgur.com/XuIMSc3)
The Stamp-C3 is a whole different fish, at 7.2 MICRO seconds per state change!!!