Go Down

Topic: Braking Function in Old (rev1?) Arduino Motor Shield (Read 186 times) previous topic - next topic

chca

Hi,

apparently I bought an older revision of the arduino motor shield, which does not quite seem to function like what the schematic of the newer rev3 suggests.

My shield looks like this: https://www.robotshop.com/en/arduino-motor-shield-rev3.html
The current one like this: https://store.arduino.cc/arduino-motor-shield-rev3

The logic circuitry on the right seems to have changed. According to the schematic

https://www.arduino.cc/en/uploads/Main/arduino_MotorShield_Rev3-schematic.pdf

I would expect that a low level on DIRA as well as a high level on BRAKEA would make the motor to be tied to ground with low impedance (except for the current sensing resistor). Instead, the DIRA state does not matter and the motor outputs are always tied to supply when BRAKEA is high. I do not want this behavior in my application.

Does anyone have a schematic of this hardware revision? I did not find one anywhere.

bos1714

Hi there!

I have found schematics and PCB layouts for each version and the schematics are identical.

The Robotshop picture shows multiple small packages, whereas the Arduino website shows one big package, which I'm guessing is the difference you mentioned.

Most likely, the bigger package has simply combined all of the small packages into one to reduce space on the PCB.

I share your concern that the braking signal sends both motor channels to the supply. Technically speaking this is acceptable, however it is much safer and a better practice to send both channels to ground for active breaking. As such, you may not be able to use this shield if you don't want this braking method.

As an alternative, the Pololu Dual MC33926 Motor Shield is very similar and can be used to power two DC motors at the same time, each with its own direction and speed. Better yet, it has leads to fit right onto an Arduino Uno, but also has leads to control it separately. I would suggest looking into this shield if you don't need the servo and solenoid capability of the Arduino shield.

https://www.pololu.com/product/2503

Good luck!

P.S. I'm new to the forums so apologies in advance if I didn't post the link correctly :)
Time line? Time isn't made out of lines. It is made out of circles. That is why clocks are round.

Go Up