Monthly Archives: December 2016

Arduino Tamagotchi, first power up!

That was more intense and exciting than I anticipated! I thought building my first “homebrew Arduino”  from an atmega 328p and controlling an OLED via I2C shouldn’t be too complicated.

In fact, it isn’t, but there are a couple of things you have to think of, especially when you do it in this contrained space.

20161204_173740sAnd actually, you can see the wiring mistake I did up there, I connected the RST of the chip and the DTR of the FTDI port wrong. But chip, FTDI and capacitor survived it…

I also did the buttons wrong as the buttons were rotated and always ON / HIGH. So, I changed the layout from this:20161204_183737s

To this:20161211_212541So now the power is on the upper part of the buttons, instead of the right (for the left buttons).

Yeah, so finally, here’s the first power up! The date / time is wrong because the third perf board with the RTC and the speaker are not connected yet, so the clock starts when the atmega is powering up:



68k homebrew computer – parts list

For building my own version of an 68000 based computer (actually, it’s the 68008, i.e. 8bit version) I recently, ordered all parts that are described in the 68k blog, here is a list together with the prices that I paid at Digi-Key. The package to about 10 days from the US.

Here’s a video walk through, followed by the list and data sheets of the chips:

all other chips for the 68k computer

all other chips for the 68k computer

Here’s the list of glue chips, together with their function and respective datasheets as links:


SN74LS32N: quadruple OR gate

SN74LS08N: quadruple AND gate

SN74LS377N: flip-flops

SN74LS139: demultiplexer for deciding whether to access flash, RAM or serial.

SN74LS00N: NAND gates

More complex chips:


SST39SF040: 4MBIT Flash ROM

ATF22V10C: GAL chip (programmable logic)

The USB host chip referred in the video is here, there is also shields for Arduino.

After posting this on Reddit, there was a great discussion on how to reduce the chip count. Some suggested that I could reduce the complexity by using the address lines in a clever way, i.e. using one pin to enable RAM access, one to enable flash access and one for the serial connector. I’d LOVE to try that out. Should I dare?