Assemble the Droids! | Pi 5 Build Log 5
Let’s take a look at building the new 3D printed head for the Raspberry Pi 5 robot.
This is a companion post to the build video, so make sure you watch that first.
New head design
It took a few attempts to get the head design right. In the end I settled on a design that is made up of three layers. The bottom layer is a base that holds the power modules and speaker. The middle layer holds the Raspberry Pi 5 and mounts the other modules. The top layer holds everything together while still exposing the components.
The advantage of the layered design is that can be 3D printed, laser cut or CNC milled easily.
I prototyped with cardboard, then transferred measurements to Onshape to create the final design.
You can see and print the design on Onshape using the link below:
Onshape - Raspberry Pi 5 Head v4
Connectors
For this version we’re using JST connectors for power and data. The PCB connectors are JST XH 2.54MM (plug male, terminal female) for all except the head connection to the body which is JST-2.54mm Terminal Wire Connector Cable Plug
We’re also using a standard servo header (2.54MM spacing) for the servo connections, these are compatible with dupont connectors.
Power and USB-C
Power can be delivered via the USB-C module or the JST connector from the body. The body must be disconnected if powering from the head directly, as this will back-feed power into the body, which it is not design to handle.
The USB-C module is a USB-C PD2.0/3.0 to DC Converter Supply Module Decoy Fast Trigger Poll and is designed to negotiate the highest possible voltage from the power supply at a maximum of 5A.
The power from either source is fed into the XL-4015 DC-DC converter which accepts 5-36V and is configured to output 5.1V for the Raspberry Pi 5 and other modules in the head, including the servo connected to the antenna. This output is feed into the custom PCB.
Custom PCB
The custom PCB is available as a KiCad project on GitHub:
KiCad Project - Modular Biped Head PCB
Gerber Files for printing - Modular Biped Head PCB
We recommend printing the PCB with JLCPCB. They sponsored the printing of this PCB and have been great to work with.
You can find their website here: JLCPCB
Antenna integration (SDR)
The antenna is a standard MCX connector, which can be connected to the Nooelec NESDR Nano 3 module to provide SDR functionality. There is also a MG92B servo connected directly to the board for antenna rotation.
Adhoc modules
Modules can be connected to three ports on side of PCB.
Each port has the following connections:
- 5V / 3.3V
- Ground
- GPIO / I2C
In the case of the 5V port, this runs via the logic level converter to change the 3.3V signal from the Pi to 5V for whichever module is connected.
I will cover this in more detail in a future post.
Want to get involved?
Read more about this and other projects
Take a look at the playlist below for previous videos in this series