Communication between esp8266 and arduino

Hallo together, I am working on a small weather station. The plan is to connect multiple sensors to an esp8266, some are using I2C as protocol. The station shall work with a battery, thus I set the esp8266 to deep sleep to save power. As I reset the esp8266 on each wakeup it should not be an issue with the i2c protocol.

In order to connect a rain gauge that requires an interrupt I will use an Arduino Nano to count the pulses from the reed switch. This Arduino shall be in deep sleep. To send the rain counter to the esp8266 I need a connection between esp8266 and arduino. One digital wire allows me to wakeup the arduino with a command that is sent by the esp8266.

Now comming to my question: Which protocol can be used to send the data from the arduino to the esp8266? I aready tried i2c but this is very complicated due to the sleep mode. Is there a better way to deal with it?

Thanks to your support. Greetings Ben

I solved the issue by using SPI as communication protocol between the ESP8266 and the Arduino.

ESP8266 is an IC. Depending on which ESP8266 module you have, it may not even necessary to have the Arduino.

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Use software serial