Hi,
I am doing a project with nano every in a car. I have successfully integrated nano every to pull BMS data via RS485 and show some elements needed on a TFT display. I am working on next steps, and this one is to put arduino in sleep mode and wake up when few things happen. First I am trying out when the car key is on.
I don't want to turn the nano every off completely as it would stop checking any data coming from BMS. I just want to wake it up from IDLE mode or other modes when the car key is on. There is a wire in a dashboard that is 0V when key is off and 13V when key is on. This is from a small EV car. The problem here is for a sec, that voltage shoots up to 20V. I am trying to separate this voltage from feeding into nano. So, I thought about using an optocoupler but since the grounds will be same (from the car/arduino since they are using same power supply) I read suggestions of using a transistor. So, here is what I have come up with.
When car is off
When car is on
I pass 13V in base, 5V from a PULLUP pin say D3 to collector and after a resistor we connect another D4 pin as well. So, when key is off, D4 will be 5V and when key is on D4 will be 0V so depending on the D4 state, we can wake up arduino/turn on the TFT display. The problem is base voltage can spike and greater than collector which doesn't seems to be recommended. I am not sure of any other way to do this.
Any suggestions are highly appreciated. Thanks.
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