Robo-Tank v5.0 is Ready

[Rob F]

Hi Mike, sorry for being so slow to reply, I was down for the count yesterday. Unfortunately it's appears there is an issue with the pump port and not the code, it seems like the main MOSFET is stuck on. Going through the logs everything is doing what it should, the start/stop is always activated when it should and after an emergency stop they don't activate.

Here's how it works.

The main ATO sensor is using pin 59 which is working ok. If you look at the code where you uncommented "ATO start/stop/emergency" you will see a line like this.

   digitalWrite(49, HIGH);

This sets the voltage on Arduino pin 49, HIGH is 3.3v and LOW is 0v. This voltage is sent to a MOSFET which turns it on/off and the MOSFET then turns the pump on/off. I'm guessing this MOSFET is always getting 3.3v so it stays on.

The backup float uses a separate MOSFET and we can see this is working correctly. When this MOSFET gets 5v from float it completes the ground path to the main MOSFET, without that ground the main MOSFET can't power up and that is operating correctly because the pump does stop when you open the backup float. 

Here's an image showing where to check voltage when ATO is on and off. I'm guessing you will have the same voltage in either mode. The voltage you read here is coming from pin 49 on Arduino, if the voltage doesn't drop to 0v when ATO is off can you remove that resistor with the arrows and see if voltage is 0v on top pad when ATO is off and 3.3v when ATO is on.

If you remove the resistor and you still don't get 0v when ATO is off then the Arduino pin is damaged, if it does change from 0-3.3v then the MOSFET is likely the problem.