Raspberry Pi Motor control HAT

Projects
1

DC Motor Control HAT

Using a Raspberry Pi to control DC motors needs additional hardware and I wanted to create a minimal sized HAT to cover a lot of requirements as listed below.

Specifications

  • 3 channel DC Motor control using SN754410ne drivers using the DFRobot motors.
  • 3 channel encoder ls7184n processing (processed before it gets to the Pi so that you just get a direction and steps # flag)
  • 2 channel MOSFET FQP30N06 switching for external devices
  • SPI breakout
  • RF24 wireless breakout
  • 5v input for Pi
  • specific motor input so that you can run different voltage motor types
  • Piezo buzzer
  • Raspberry Pi GPIO header
  • 3 x RJ45 headers for connection to the motors to have motor control and pass back the encoder data.

Board

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Schematic

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This add on HAT uses just about every single GPIO pin to achieve motion control of 3 axis of DC motors.
The encoder IC provides a direction and utilises the A and B channels from the Motor encoder to give an accurate position.

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2

Sick write-up Andrew!

Thats a sick IC, if I ever need to read an encoder on a Pi I’ll be sure to jump on this!

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3

It is an awesome IC, pity that it is difficult to get. I had to order 50 from the USA and all the associated costs that go along with that, however now that I am using it, the timing issues that I was having when reading the A and B channels went away.

The Encoder IC coupled with the DFRobot mini DC Encoder motors is a very sweet combination, the only component that I would like to change over time is the motor driver, purely because I cant get the braking function to work.
If the motors would stop faster it would be ideal, currently getting about 4-5 encoder rotations after commanding it to stop.
The other driver issue is that the motors really wont drive at any other speed than 100% via PWM, the torque is simply reduced too much.
That was the first test in replacing braking, slow down the motor when coming up to the set-point, but it would always end up stalling, unfortunately.

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