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 | 3 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 | 14 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 | 10 Comments | Tags: , , , ,
8 Aug

Local Restaurants: The Ann Arbor Experience

Polaroid Shots of Ann Arbor

Polaroid Shots of Ann Arbor

Ann Arbor is known for its exceptional selection of local restaurants, but picking a place to try can be overwhelming. Here is a short list of my favorite places to eat in town that you won’t find anywhere else.

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Food | 1 Comment | Tags: , , , , , , , , , , , ,
31 May

The CANable: a small USB to CAN adapter


The CANable is now available for purchase on the Protofusion store!

The CANable is a hardware clone of Eric Evenchick’s CANtact project, an open-hardware USB to CAN adapter compatible with socketcan. I took his design and reworked the hardware to be a bit more suitable for my personal needs, with a screw terminal instead of a DB9 connector and a much smaller PCB.

The design is open-source hardware and the schematic is nearly identical to CANtact except CANable uses the STM32L042’s onboard high speed oscillator, has a micro-USB connector, and has a smaller 3.3v regulator. Feel free to pull down the hardware source and the firmware (a forked version of the CANtact firmware that uses the internal oscillator instead of an external crystal).

Update: CANable support has been merged into the CANtact firmware. Just change the define in main.c for CANable and you should be good to go!

I’m currently not producing these boards, but you may fabricate your own from the source files linked above. If there’s enough interest I may consider fabricating and selling some boards. Drop a comment if you’re interested!

Projects | 15 Comments | Tags: , , ,