encounters with electron•ics

by flabbergast

The bat board - a breakout for STM32 in LQFP48

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I like the size of the ARM Teensies, and I’ve seen (and tried) a STM32L4 breakout of this size here: Dragonfly. However I wanted something cheaper, simpler, and hand-solderable (as usual). Hence a breakout board I dubbed “the bat board” (because I’m not good with names).

ARM breakouts

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A summary of hand-solderable ARM breakout boards that I’ve made over the past year (STM32F042F6P6, STM32F030F4P6, MKL27Z256VLH4).

BBB-RFM69 (Beaglebone Black radio half-cape)

A BeagleBone Black half-cape featuring: an atmega328p, a RFM69(H)W radio and a DS3231 RTC with battery backup.

X-A4U-stick rev2

Following up on X-A4U-stick rev1, I’ve made another revision of the board, again Open Hardware.

X-A4U-stick rev1

Delving into the world of designing PCBs and SMT soldering, I’ve made an USB stick with atxmega128a4u, microSD socket and a couple more goodies.

Remarks about soldering tinyUSBboard rev4 (SMT) kit

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This post is about soldering matrixstorm’s tinyUSBboard rev4 - you can get a kit at Tindie for an incredible price of $4.

A microSD + crypto shield for AVR stick

A shield for Stephan’s fantastic AVR stick is in the works! It has the same format as the AVR stick itself, 5cm x 2.5cm. I want to use the AVR stick as an encrypted “mass” storage, so the features are

Encrypted USB stick with atxmega128a3u

Stephan Bärwolf’s AVR stick is a wonderful device to play with: it is a breakout of sorts for ATMEL’s atxmega128a3u chip, and I like how it is designed:

JeeNode Micro with TMP102

I bought a TMP102 breakout, made by Sparkfun and soldered it onto my JeeNode Micro.

Notes on programming JeeNode Micro with Arduino

Having gotten a JeeNode Micro (with a RFM69CW instead of the usual RFM12B), I needed to figure out a way to program it from Arduino GUI. A Bus Pirate from Dangerous Prototypes came in really handy:

RFu-328 with RFM69CW and Thermistor coin cell board

As I’ve been moving from Ciseco’s radios to HopeRF’s RFM69CW’s, my XRF + thermistor sensor from Ciseco needed to be “converted” as well. As RFµ-328 has the same footprint as XRF (except it’s “sticking out” from the pins at the other end), with similar pinout (GND, VCC and some input/output pins at the same places), I thought that I would just replace the XRF with a RFµ-328 with a proper firmware. Success!

From Ciseco to HopeRF

Recently there were several things related to Ciseco that annoyed me a bit (RFµ-328 is going to get a bigger footprint; they removed an item from a bundle in their shop from one day to the next without changing the price or announcing anything; buying SRF radios can be now only in bulk (10 minimum) UPDATE: Ciseco rescinded the decision; SRFs are available individually again. Well, too late for me.). Don’t get me wrong, they still make cool stuff (like the RFµ-328), but I didn’t want to depend on them for radio modules.

USB tester

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Inspired by FriedCircuits’ USB Tester 2.0, I’ve decided that instead of ordering one, I’ll make one myself on a protoboard.

HVSP fuse resetter

Having looked at simpleavr’s HVSP fuse resetter, I wanted to make one myself, since I play with attiny85’s and sometimes I want to reset the fuses to “unlock” an attiny with disabled reset.

Attiny25/45/85 programming shield for my attiny USB stick

Having looked longingly at Sparkfun’s Tiny AVR programmer, I wanted the same functionality for my attiny USB stick. So I scrounged some old arduino stacking headers, and made another shield for it: Attiny25/45/85 programming shield!

USB stick with attiny85

About a year ago, I made a sort of a DigiSpark, or LittleWire clone on a stripboard. I’ve come back to it now and made a couple of shields.

A "paperPCB" amplifier with LM386

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I wanted to make a simple amplifier (essentially for use with Arduino), a little googling showed that one of the simplest ones uses LM386 operational amplifier chip. There are very many slightly different schematics to be found on how to go about using LM386. In the end, I used the one below, a combination of what I found and which parts I had on hand ;)

Monitoring temperatures with ruby and XRF

I’ve written about monitoring the temperature using a Raspberry Pi (running a node.js app) and XRF radios from Ciseco, communicating together using LLAP messages.


For the impatient: the project is hosted on github here: node-llap.

Intrigued by the cheap and easy-to-use radios from Ciseco, I set out to make a sensor data collecting station out of my Raspberry Pi. The goal is to have the Pi act as a central unit, with sensors reporting to it, and the Pi serving the data in a visually pleasant and easily comprehensible way over the net. Plus, it should be reasonably easy to hack, so that modifications to suit particular needs are quick.

Roll a dice / afternoon soldering exercise

Inspired by a Sunday fun rolling dice, one afternoon I ventured to build my own dice on a protoboard.

VUSBtiny expansion board

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The really tiny VUSBtiny programmer I’ve made is a handy thing, but hooking up the wires to the flat 6 pin connector gets annoying. So I’ve soldered a ZIF socket onto a piece of a stripboard, a couple of wires, some headers…

Stripboard diagrams for vusbtiny and tinyUSBboard

Here are drawings of the stripboard layout for the boards I’ve soldered (vusbtiny programmer and tinyUSBboard), together with an extension board for the programmer (photo in an upcoming post).

ATmega stickers with pinout

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As I’ve started using ATmega ICs on a breadboard or a tinyUSBboard, looking up the pinouts became a chore. I’m not the first to come up with the sticker – I found a couple of them on the web, even orderable from Adafruit for instance, but I wasn’t happy with those I found. The main reason is that sometimes I want to use the Arduino IDE to program them, sometimes straight avr-gcc with a programmer. So I made stickers in Inkscape which has both pinouts: red for arduino, black for original names from ATMEL. Plus indicators which pins support PWM. If you’re interested, grab a svg – it has drawings for ATmega328p and ATmega8.

Self-made tinyUSBboard

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As a second exercise in soldering, I decided to make a tinyUSBboard. It’s a pretty cool gadget – a prototyping board with an AVR chip (can be programmed through the Arduino IDE). The USBasploader bootloader makes it very easy to program the chip without any extra ISP programmer; to run the bootloader just hold the “Program button” while resetting the board. Check out its website for some examples, and also the files to add to the Arduino IDE for programming through it.

VUSBtiny AVR programmer

As an exercise in soldering (to which I’m quite new), I decided to take the VUSBtiny programmer on a breadboard and make one on a piece of a stripboard. I used a stripboard with 3x1 strips (so I didn’t have to etch anything off). The schematic is of course the same as the original breadboard version, except I added female headers for the USB and the ISP-out connection. Since I routed some wires underneath the ATtiny, instead of soldering the IC directly, I let it “stand” on a pair of precision female headers. Of course a dedicated socket is also fine (but I didn’t have one); I think one’d need a precision one, since there’s not much space underneath the usual one.

Variable light (Arduino sketch)


Control the light intensity of a LED diode by the length of a button press: if just clicked, then turn it on all the way; if held for a longer time, slowly change the intensity up and down. Releasing just keeps the current intensity.