michaelh@juju.net.nz 2017-05-15 https://juju.net.nz/michaelh/project/spdbt/


A fast indoor mousebot for playing with rover control and navigation.


Context that led to this project.


What the project must fufill.


spdbt is made from parts I already have which are:

  • Raspberry Pi Zero W
  • Picon Zero I/O board
  • C270 USB camera
  • FIT0441 12 V 159 RPM motor
  • HC-450 3S LiPo (~30x55x18) with XT connectors (similar to this)
  • Pololu 5V regulator D24V22F5
  • ST7735 1.8” 160x128 LCD


The deliverables are:

  • OpenSCAD models for the mechanicals
  • Ansible rules for configuring the rover
  • Firmware for the rover
  • If needed, updated firmware for the Picon Zero
  • Photos showing the assembly


Chunky steps along the way

Milestone Week Result
M1 W1 All foos have bars barred
M2 W3 All bazs are frobbed

Risks and mitigations

What are the risks, likelyhood, impact, and ways of handling them?

Alternatives considered

Do nothing…


FIT0411 pinout

  • Blue (left most): PWM. Take to GND for full speed.
  • Black: GND / Supply negative
  • Yellow: Direction
  • Green: encoder output. ~680 Hz at full speed
  • Red (right most): 12V

Picon Zero pins

Source: https://github.com/4tronix/PiconZero

Protocol: http://heeed.net/a-few-notes-on-i2c/

TODO(michaelh): uses software PWM using a delay(). Check the accuracy especially during transfers.

Pins are {6, 7, 8, 11}, {9, 10, 2, 3, 4, 5}. Good news with software PWM is any pin can do any function.