October 2018

Roller Blind controls

Rob B. showed his roller blind control using a Wemos D1 R2, relay board and worm drive motor for control. Using a Raspberry Pi as a MQTT broker.

Persistence of Vision (POV)


Bill S. showed off his POV display

The microcontroller used is a ATtiny85, which is an AVR chip. It doesn’t have a USB serial interface to upload Arduino sketch, so an external programmer is used for the 8-pin device.

Here is the code

It initially didn’t work for him, it turned out he had the pin assignments wrong.

Here is the final result.

POV Display

Arcade buttons and joystick

Bill S. also “donated” a Betop btp-4121 computer arcade. Retropie recognises it out-of-the-box.

Arduino Timers

I have written up on the blog about how to configure Arduino Timers . It has taken me a while, but I think I have finally conquered how to configure timers for the base scenario - run a task every N seconds.

There is one other scenario that I haven’t handled which I should document - Start a timer on a button press, and in the handler, stop the timer (ie. a one-shot timer)

Show and Tell

I can show off two hobby projects.

One is a turntable control using a servo motor, raspberry pi and an android app.

The android app was written with App Inventor 2, which is a Scratch-like environment. The communication between the android app and raspberry pi happens via bluetooth LE. On the pi side, bluetooth receiver written in nodejs, servo control written in python.

The other is connecting a gameport joystick to a raspberry pi via an Arduino here.

Started by connecting gameport pins to Arduino analog pins, then reading raw values. The values are then sent to the pi via Serial connection. On the Pi, wrote a python script that creates a virtual input device, then send keys to that device. I got it working on Retropie!

Problems with POE hat for Raspberry Pi 3 B+

Interesting video on EEVBlog on the issue POE hat woes

The issue is written about here

Raspberry Pi Magazines

We all know about Magpi magazine

The magazine that was not known to me was HackSpace magazine. Like magpi, back issues are available free of charge as a pdf.