The first goal of the LoCoRo was to make the robot “low cost”. Now it’s time to make it easier to build.
Feedback from testers was that “it’s easy to make simple mistakes connecting all of the GPIO wires.” Sarah Petkus provided a good solution – develop a printed circuit board (PCB).
Here is the prototype …
This is a manually wired “plate”. A Raspberry Pi plate differs from a “hat” by not having the digital identification circuit. Otherwise, it provides the same function.
This plate contains the power input (5v-9v), on-off switch, and voltage regulator. It has the servo control board, a 128×64 pixel display, and a 9-axis gyro / compass / accelerometer.
The plate uses a 40-pin connector which plugs directly onto the Raspberry Pi GPIO. The connector uses “extra long pins” so all of the GPIO is still accessible for additional electronics.
An etched PCB would also provide convenience pins for more I2C devices, at least 4 channels of analog-digital signals, as well as a bank of 3v, 5v, and ground pins.
Ideally, the design would contain a battery, 8 channels of analog-digital support, and input/output voltage display. However, there was no way to fit all of the components – even on two stacked plates – because too many modules needed to be on the top plate. With some creativity, it may still be possible.
It would be possible to fit everything if the PCB were designed for discrete electronics rather than the pre-built modules – which take up extra space – but then the complexity of soldering would be beyond most users.
Everything is a compromise.