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If you want to find out exactly what a venerable Z80 is doing on its bus while executing instructions, in this post I outlined a dongle and the software that will let you see that. Using just a few components and connecting them to an Arduino Mega, you can trace instructions clock by clock and observe what's happening on the bus.

...continue reading "Arduino and ZiLOG Z80"

This article is a follow-up to the "RS232 and Raspberry Pi" (link)

The same MAX board that I had also worked with Arduino at 5V although it was designed for 3.3V operation (capacitors onboard were sized for 3.3V operation - page 10 of MAX3243 datasheet). Still, it seemed to work fine up to the 28800 baud rate. Any faster and the software starts detecting data framing errors and the data becomes corrupted.

However, that was purely a design limitation of that particular RS232 board that I had.

...continue reading "RS232 and Arduino"

The most common (and the simplest) use of Arduino ADC (analog to digital converter) uses its internal Vcc reference voltage, and that voltage is 5V, right?

The internal reference voltage varies around 5V, and it is rarely exactly 5V. This article explains that in detail:

...continue reading "Accuracy of Arduino’s ADC"


A weather station, Ambient Weather WS-2080 that I installed in my backyard has a receiver unit with a pretty nasty hardware issue: occasionally, its USB interface would hard hang. It could happen twice a week or once a month – it is very unpredictable and highly annoying. Once it happens, nothing short of a power reset of the receiver unit would fix it. You’d have to remove the battery or unplug the USB if you powered it through it. I've finally got around to fixing it. If you have a similar problem with that weather station, you may be interested to read on...

...continue reading "Ambient Weather WS-2080 hang fix"