RAREblog

A working prototype I've now got a home-brew Arduino clone reading the keyboard and sending key-presses to a micro:bit using I2C. Preparing the Arduino clone was trickier than usual. As I mentioned in yesterday's post , the Arduino needs to run at 3.3 volts. That's the working voltage (V cc ) for the micro:bit, the Pi and the Jetson Nano. Connecting I2C lines from a 5v device would damage them, so 3.3 v operation is essential. I have a good stock of ATmega328P chips left over from the days when I was running Shrimping workshops. The ATmega328P  works well at 3.3 volts, so long as the clock frequency is no more than 8 MHz . Most Arduinos run at 5v with a clock speed of 16 MHz, so there's work to do.   8 MHz clock issues If I2C is to work reliably at 8 MHz the Arduino needs to be configured for an 8 MHz clock, and it needs a bootloader that works at that clock rate. My first step was to wire up a working clone on a breadboard with an 8 MHz crystal and i...

Yesterday's Raspberry Jam at Covent Garden was amazing. The Dragon Hall was packed with Raspberry Pi enthusiasts of all ages and the whole event pulsed with energy. I ran the Shrimping It! workshop  with some very welcome help from Jim Darby (@HackerJimbo). I'd never had a group that large, and I'd managed to bring the wrong glasses, so Jim saved the day. By the end of the day we had lots and lots of LEDs blinking under program control, and lots of experimenters who'd discovered how breadboards work and what a capacitor looks like. The organisers did a fantastic job, and made everyone very welcome. I'll certainly be going again. The next Covent Garden Jam will be on 20th June, and I've got the date in my diary.