15 Jul

HydroBot: Measuring Atmospheric Conditions


AirSense is a HydroBot module designed to measure air temperature, relative humidity, and barometric pressure. It uses the Bosch BME280 atmospheric sensor to take measurements and sends the results out over CAN. The module can measure temperatures from 0 to +65°C with ±1°C accuracy, humidity from 0 to 100% with ±3% accuracy, and pressure from 300 to 1100 hPa with ±1 hPa accuracy. Three LEDs indicate device status, CAN activity, and error states. Read more »

HydroBot, Projects | No Comments | Tags: , , , , , , ,
1 Jul



HydroBot is a modular control system for automating hydroponic gardens. This system is designed with three objectives in mind. First, it will facilitate optimal growing techniques by using scheduling and feedback control loops to maintain state and adapt to changing conditions. Second, it will simplify controls interfaces, making setup and use easier for less tech-savvy gardeners. Finally, the components will be designed in a modular way to increase flexibility and support every imaginable garden configuration. HydroBot aims to bring sensors and actuators together through automation, which will allow hobby growers to focus on growing and not on constantly monitoring and adjusting the environment to keep their garden stable. Read more »

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6 Mar

Therm RTD

Therm RTD

Therm RTD is an addition to the Therm PID Controller family, with support for RTD temperature sensors. RTDs (or Resistance Temperature Detectors) use a coil of fine wire made from a material (usually platinum, copper or nickel) that has a very predictable temperature coefficient of resistance (or change in resistance as temperature changes). RTDs are generally more accurate and stable than thermocouples, and have a much greater range than thermistors – although they can tend to be more expensive than both. Read more »

Projects, therm | 8 Comments | Tags: , , , ,
29 Feb

FeatherHAB Source Code Released!

featherhab-0.1FeatherHAB hardware and software source code are now available for download! The hardware is released under the Attribution-ShareAlike 4.0 International license and the firmware is released under the GNU Affero Public License.

FeatherHAB Features:

  • STM32F0 microcontroller
  • SI446x transmitter broadcasting APRS on 144.390MHz
  • ublox MAX8 GPS module for position tracking
  • Buck-boost power supply for running off of single LiMnO2 cells
  • Opencm3-based firmware compiled with GCC ARM

A st-link programming adapter, blackmagic probe, or similar is required to flash FeatherHAB boards. You will also need some means of connecting to the programming pads on the FeatherHAB PCB. You can solder wires directly to the programming pads, or you can build a ProtoProg adapter.

Building your own FeatherHAB or modding the design? Drop a comment below and share your progress!

Announcements, HAB, Projects | 18 Comments | Tags: , , ,
28 Feb

Open-Source SWD Programming Adapter


After making the switch from AVR to STM32 microcontrollers, I redesigned my old 6-pin ICSP pogo-programming adapter for SWD. The new design allows programming with pogo pins or a small pin header soldered to the pogo pads for debugging, all with the same cable. The footprint uses surface mount pads only, so it can be placed on even the most compact board layouts.

Read more »

Projects, ProtoProg | 2 Comments | Tags: , ,
27 Feb

CANable now available for purchase!


The CANable USB to CAN adapter is now available for purchase on the Protofusion Tindie store! The CANable is an open-source USB to CAN adapter that works on Linux, Mac and Windows. The CANable shows up as a virtual serial port on your computer and provides a standard serial-line CAN interface. CANable is also compatible with a Python CAN library so you can easily code scripts that interface with the bus. Check out canable.io for more information.

Announcements, Projects | 1 Comment | Tags: , , , ,
6 Dec

Tenergy LiFePO4 CR123 Cell Test


I stumbled upon Tenergy’s lithium iron phosphate CR123 cells when looking for a fairly compact cylindrical rechargeable battery. The Tenergy RCR123A LiFePO4 cell, as listed on Tenergy’s website, supposedly has a nominal voltage of 3v and a nominal capacity of 750mAh. Both of these values seemed a bit unusual, so I ran the battery through a discharge test to get some realistic data on what this cell is capable of. Note that many consumer battery manufacturers publish capacity numbers that are more than 200% of the real-world value, so this isn’t a unique case.

Read more »

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31 Oct

DIY 3D-Printed Model Rocket


3… 2… 1… Blast off!

Space has often been referred to as the final frontier, and many who look towards the heavens find themselves wondering what might be hiding just beyond our reach. Although commercial space missions cost well into the millions and even billions of dollars, model rocket enthusiasts have been striving to reach just a bit closer to space for decades. Estes model rockets have allowed generations of kids to dream about one day escaping the earth’s gravity and venturing into the unknown. I like to think that a bit of exploratory spirit can be found in everyone, and I am certainly no exception. Read more »

Uncategorized | No Comments
19 Oct

FeatherHAB: 2-gram High Altitude Balloon Tracker

FeatherHAB Balloon Tracker

FeatherHAB is a lightweight, small, and inexpensive balloon tracker. It tracks the location of a balloon with GPS and broadcasts the balloon’s position to the APRS network on 144.390MHz. The tracker is built around a Ublox MAX8 GPS module and a custom RF transmitter designed with the Silicon Labs Si446x transceiver IC. Power is supplied by a single-cell Lithium battery, which runs through a tiny buck-boost converter to power the system. The total weight comes in at about 2 grams without a battery.

Read more »

HAB, Projects | 2 Comments | Tags: , , , , , , ,
23 Aug

Therm: a Tiny PID Controller

Therm PCB top

Therm is a very small PID controller with an OLED display, thermocouple interface, and USB port. It can switch an external solid-state relay for driving large loads, or a transistor for driving small loads. When attached to a computer, it enumerates as a USB serial port for easy control and logging of data. The design is based around a STM32F0 microcontroller and the MAX31855 thermocouple-to-digital IC (note: an RTD version of therm is in the works). Read more »

Projects, therm | 13 Comments | Tags: , , , ,