Comments: Sending Sensor Data Over WiFi

Just as a "heads up", if you try to compare the pressure measured with that reported by, say, the National Weather Service, you'll probably see a lower reading on yours than on theirs. That's because they normally adjust their readings for altitude, and unless you happen to be within a hundred or so feet of mean sea level, the difference can be substantial.

For my sensors, I've implemented Babinet's Formula to correct for this -- see this for details. (It also requires the "mean temperature", but I just use the current temperature value.)

If you wish to have multiple "transmitters" and/or multiple "receivers", I would suggest investigating something called "MQTT" as a data protocol. At least, that's what I use, with the "broker" running on a Raspberry Pi.

I was unable to get this to work until I found a fix at

https://github.com/espressif/arduino-esp32/issues/6029

The "register peer" part of the transmitter code needs an addition line:

// Register peer esp_now_peer_info_t peerInfo;

memset(&peerInfo.peer_addr, 0, sizeof(peerInfo)); // <--- This line needs to be added

memcpy(peerInfo.peer_addr, broadcastAddress, 6);

peerInfo.channel = 0;

peerInfo.encrypt = false;

Not sure if I missed this somewhere, but the code to find the MAC address returns an error

class wificlass has no member named mode

It worked when I removed the #include <WiFi.h> and instead included the ESP8266WifFi library.

Perhaps there's something here telling us that and I just missed it, but I had to dig around a while to figure it out. Hope this helps.