Robot acting weird (voltage regulation issues?)

Other Hardware Motors, Mechanics, Power and CNC
1

Alright, so I'm getting to work on my combat robot to get it ready for an event. I ran into a bunch of issues last night and I'm struggling for an explanation. I do not have a wiring diagram but I can quickly explain what it looks like.

There is an RF nano (Arduino nano with NRF24L01 built in with CE on 9 and CSN on 10), a brushless ESC, a mini L298N h bridge, and a 3S LiPo. The RF nano is connected to the L298N on on pins 3, 5, 6, and 11, and the ESC on pin 12. The nano is powered from it's 5V and GND pins via the ESC's BEC. The main power lines on the ESC and L298N are fed from the 3S LiPo output.

The issues are as follows:

  • Writing to pin 3 as high and 5 as low makes them both high and the motor does not turn. Using the other motor on 6 and 11, it does rotate as normal. This is if the nano is directly programmed.
  • Using 2S LiPo voltage, the system functions, but on 3S LiPo voltage, the motors don't move.
  • The NRF24L01 would not work (Robin2's communication test said that the Arduino was not communicating with the NRF).

Issues 1 and 3 (2 was not related to the nano) were solved upon cutting the RF nano out of the robot and testing it by itself. This leads me to assume that something connected to the nano was causing problems. I have no idea what, though. I'm assuming it's the ESC because the L298N is brand new and the RF nano clearly works fine once it's disconnected from the bot.

I'm thinking that this is caused by poor BEC voltage regulation by the ESC, causing the Arduino to become unstable. I think this because the 5V lines read as 4.43V on my meter, which is below the 4.5V minimum that is usually considered "safe" for 5V devices. Also, the ESC was getting warm, even though it was doing literally nothing except from regulating the voltage. There is one other thing that could be the cause (though this seems unlikely), which is EMI from the drive motors. This doesn't explain the battery problem though, so that would have to be caused by something else (maybe the hot ESC is to blame here, too).

My question is this: Is the problem caused by EMI, voltage regulation, or a combination of both? Or is it something else entirely?

2

You better create schematics. Helpers will not do it from Your words.
Many times the issue is found in connections missing and not mentioned.

Proper powering is critical. If the powering is insufficient software analysis is a waste of time.

3

I cannot see how a missing connection would cause any of these problems, but I will create a diagram anyways.

EDIT - @Railroader

bot_schematic
bot_schematic731×429 7.68 KB

"Vcc" is 3S battery voltage (~11.1V)

4

Quick update. So I decided to rebuild the whole thing and then systematically cut wires until it worked. Once I cut the ground wire from the ESC, it began functioning. This means that somehow the voltage regulation from the ESC was not working correctly.

EDIT - I have a buck/boost converter lying around. I'm going to try to integrate so I can separate the nano from the main power system and power it directly from 12V, converting to 7V and then feeding to VIN. I'm aware that the AMS1117 can usually handle 12V but in my experience that is not the case. The difficulty here will be staying in the weight limit.

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