- Wed Jan 29, 2020 9:27 am
#85460
Hi everyone
For a personal gardening project I am planning to control several 5V and 3.3V sensors, a tft screen and to send via wifi all data to my MQTT gateway, all with a MEGA 2560 (for the tft screen and the 5V sensors) and a Lolin NodeMCU V3 (for a 3.3V BME280 sensor and wifi comunication).
1. I am wandering if, instead of powering both MCUs independently, it is possible to power the Lolin from the MEGA. I have available a couple of power adaptors, 5Vs / 9Vs / 12V, having the 5Vs higher amperage than the 9V / 12V.
2. Are specific pull-up resistors required for the I2C connection? I have read different answers in many forums. Some say that the Lolin is 5V tolerant, so a direct connection is fine, but some others mention that this is ok for testing, but not for a long term solution. My project will be running 24/7.
Attached there is a diagram of both connections.
I still have a lot to learn, and I am pretty scared of causing a fire.
Thank you!
For a personal gardening project I am planning to control several 5V and 3.3V sensors, a tft screen and to send via wifi all data to my MQTT gateway, all with a MEGA 2560 (for the tft screen and the 5V sensors) and a Lolin NodeMCU V3 (for a 3.3V BME280 sensor and wifi comunication).
1. I am wandering if, instead of powering both MCUs independently, it is possible to power the Lolin from the MEGA. I have available a couple of power adaptors, 5Vs / 9Vs / 12V, having the 5Vs higher amperage than the 9V / 12V.
2. Are specific pull-up resistors required for the I2C connection? I have read different answers in many forums. Some say that the Lolin is 5V tolerant, so a direct connection is fine, but some others mention that this is ok for testing, but not for a long term solution. My project will be running 24/7.
Attached there is a diagram of both connections.
I still have a lot to learn, and I am pretty scared of causing a fire.
Thank you!
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