Trouble using 2 controllers simultaneously

Submitted by panayiotis on Fri, 09/23/2022 - 11:09

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Hi all,

I have built a robot using a RasPi 4, 2 ThunderBorg motor controllers and 8 AA batteries. Each motor controller works fine when tested individually, but when both are connected to the Pi only the controller that is connected to the battery pack seems to be working.

This has me buffled somewhat, I have followed the wiring instructions to the best of my ability, but can only assume I have wired sth incorrectly - or maybe that the power supply is not strong enough?

I have included some photos below, I would appreciate any suggestion you could give me.

Thank you,
Panayiotis

Images: 
piborg's picture

piborg

Fri, 09/23/2022 - 18:00

Not to worry, it's just a simple misunderstanding :)

Each ThunderBorg gets power for running the motors from its own V+ and GND connections. This means that the ThunderBorg that is not connected to the battery pack has no power to supply to the motors, so they do not run.

The connections between the ThunderBorgs and to the Pi only carry the lower logic voltages (5V and 3.3V) along with the communications used to control the boards. There is no wire carrying the full battery voltage between the boards.

All you need to do is connect the battery pack to the V+ and GND on both boards. This can be done by having an extra wire connected between the two V+ terminals and the same for the GND terminals.

Also if you have not already you will need to have different I2C addresses configured for each ThunderBorg as explained under "Multiple Boards" on the Getting Started page.

panayiotis

Fri, 09/23/2022 - 19:22

That makes so much more sense.... Thank you so much - I could have spent a lot of time trying to find the solution on this one.... :-)

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