RPi Compute Module 4 small form factor break out board

Projects and Learning
#1

It is common to run something like a RPi as a high level controller for things like: computer vision, AI, ROS, SLAM and high level user interfaces.

RPi zero does provide a small forma factor but is very light on processing power for some of the complex operation. A RPi4 has much more computing power especially if over clocked but has a much larger form factor which is also a disadvantage when trying to squeeze it into a robot.

The RPi compute module 4 is purposely design for use in embedded applications with form factor only slightly larger than a RPi4 but with more features than a RPi4 but doesn’t have anything broken out to connectors, rather everything is accessed via the high density headers.

Here is a very interesting small form factor break out board GitHub - harlab/CM4Ext_Nano: Smallest, yet feature rich baseboard for Raspberry Pi Compute Module 4

I am also wondering if someone in the know might be interested in designing a breakout board especially designed for using on robotics, I think aimed at the CM-550 controller??

#2

Hi @Out_of_the_BOTS, great post and interesting idea! It would be quite cool to see a carrier board for robotics designed for the Compute Module 4. If designed with DYNAMIXEL in mind it could even include built-in half duplex communication circuits for easy connection to DYNAMIXELs.

I know a number of our members here have designed interface boards for DYNAMIXELs in different applications. @JosueGtz has created an interface for Raspberry Pi, and
@hierophect also made their own interface for Adafruit Feather pinout boards.

Another power user @roboteer is very experienced with custom projects involving the CM-550 and ROBOTIS software, as well as custom programming with these.

Would this be related to upgrading an ENGINEER KIT 2 robot (combining the CM-550 with Raspberry Pi Computer Module 4) or is there another reason you are interested in the CM-550?

#3

Yes I have ordered both kits of the Robotis Engineer.

Having experience in building many robots myself this kit is of great interest to me. I have build robots controlled by RPi and I have built robots controlled by Micro controllers using both bare metal embbed C and also mircopython. I find RPi is great for computationally heavy tasks like computer vision but it is really poor at real time stuff and of course micro controllers don’t perform tasks requiring heaving computation or large RAM. Mixing the 2 together is best solution. Micro controller for low level stuff and RPi for high level stuff. I also like micropython because it makes for very fast development and it works by sitting on top of C and calling the underlying C functions so you can mix C and python.

The CM-550 to me looks like a great low level controller (STM32F4 is my favorite family of MCUs to work with).

I think a carrier board that breaks out the camera port, display port, UART connection to CM-550 and rest of GPIO, USB C, micro HDMI and the needed USB connection to boot and pins to force boot loader mode for updating OS on the EMMc storage. Then to add a small amp and speaker to play sound from the I2S peripheral on the RPi and small mic to record on the I2S.

Something like this can be made very small to easily fit on a robot.