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Hardware design for the Peanut altimeter.
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A modern, tiny, and hackable altimeter for hobby rocketry.
Features include:
Tech specs:
Take a look at Peanut's layout and electrical schematics here.
Peanut is also the subject of one of my 2026 Apache Community over Code conference presentations. I discuss the process of designing an altimeter with NuttX in mind, as well as what considerations go into robust firmware design.
Thank you to PCBWay for sponsoring the manufacture of this project's PCBs!
The firmware for this board is made using the Apache NuttX RTOS, an open-source embedded RTOS with an incredible community and an excellent feature set.
Firmware is spread across a few repositories. If you are compiling yourself, you'll need:
rocket-altimeterInstructions for how to configure, compile and flash firmware can be found in
the Peanut BSP and rocket-altimeter
repositories. Pre-built firmware binaries are made available with each release
under the Peanut BSP repository.
All hardware designs & firmware for Peanut are open-sourced and available under permissive licensing.
The device itself is programmable over the USB-C interface using Espressif's
esptool, so users can tweak the firmware or write their own and easily
re-program the device. Want the buzzer to play custom audio? Want to change the
meaning of the "START" LED? Want to add more features to the Bluetooth
interface, or make the altimeter operate over WiFi instead? You can program
whatever you want into it!
If you'd like to fly Peanut, take a look at the 3D models so you can design your av-bay in CAD. This directory also contains the key dimensions of Peanut for size and mounting holes.
NOTE: A user manual for Peanut is coming soon! For now, be aware that Peanut is only rated for 4V2 LiPo/Li-ion batteries (3V7 nominal). You should only use batteries without overcurrent protection if you are flying Peanut for deployment purposes. Otherwise, pyro channels may not be able to draw sufficient current when fired.
If you want to make your own Peanut Altimeter, the component cost for the board is roughly $35 CAD. You can get PCB blanks from a manufacturer of your choice (i.e. PCBWay). You should only need to verify the trace widths of the Bluetooth RF trace depending on the differences between your manufacturer's PCB stackup and mine.
NOTE: This board was not designed with hand-soldering in mind (aside from the backside). My manufacture process is to use solder paste, a stencil and a hot plate to do the top-side components. There are 0402 components which are manageable with steady hands and tweezers.
My experience using PCBWay could not have been easier. They provide a plugin for KiCAD that directly exports your manufacturing files for order to their web quote interface. I only hand to click the button and choose some parameters for my board to get everything ordered.
My designs arrived on time, well package and the stencil was really high quality with a large aluminum frame. I had no issues with the fine details (in copper and on silkscreen) with such a small board, PCBWay nailed it.