Over the weekend I made a 4 digit 7 segment display countdown timer. The display driver is the SevSeg library, which I just grabbed for ease of use, on the Raspberry Pi I’ve previously just written the driver myself by mapping letters/numbers to an array of segments with HIGH/LOW states (Youtube link) but that was only a single digit display. I don’t call the delay() function at all in the code, instead it uses timers and millis() so the button presses are instantly detected and the digits redraw quicker so the countdown happens in realtime – tested with a stopwatch.

I’ve revisited my ATtiny85-based LED strip driver project, and finally got around to soldering it onto veroboard, added a proper switching regulator instead of the awful 7805/capacitor setup, and screw terminals to attach the strip which is much more secure than just pin headers. It pulls 100mA @ 12v most of the time, topping out at 200mA when on full white constantly, not bad for over a foot of LED strip that I’m testing with.

I’ve ditched the Arduino Uno and Adafruit motor shield, far too many limitations around power and pins. So now my robot is mostly done – using a bare ATMega328P and a single L293D H-bridge chip which I wrote a small library for. I’ve solved the 7.4/6v/5v problem by feeding the 7.4v output from the 18650’s to a Mini DC/DC switching regulator that outputs 6V for the motors, and then a diode drops that to about 5.

I’ve started to receive the components I need for my 2WD obstacle-avoiding robot. I got the motor shield which is a clone of the Adafruit one it seems, however its quite poorly made – the silkscreen that says which servo is which is backwards, one of the L293D chips wasn’t sitting straight in its socket, the high voltage terminal blocks for the motors are dangerously close to shorting on the Uno’s ICSP pins and USB socket (I fixed with some insulating tape) and the reset button is soldered at a bit of an angle!

I’ve been getting back into the ESP8266 now that there is an Arduino port for it. I’ve not used the full IDE, just installed the hardware core into my existing vanilla 1.6.3 IDE using this setup. I then made a little DS18B20 and ESP-01 module, which runs off of 2xAA batteries which are boosted to 3.3v using the Pololu step-up regulator. It started off as a 3xAA battery setup with a diode dropping the voltage down from 3.