I've been doing some work recently with a little Silicon Labs EFM8UB3 microcontroller. This is a nice 8051 clone with a bunch of peripherals all in a QFN24 package. I've been using a minimal development board Silicon Labs calls the Thunderboard. It's mostly fine, but it has one failure mode that's pretty annoying. This article is about how to back out of that failure mode if you encounter it.

The Thunderboard has a built-in JLink debugger, and it's unfortunately possible to put the MCU into a state where the debugger can't talk to it. That means that you can't program the board any more, so you might think you're stuck. You're not!

One thing I need to do for my pump monitor is to determine when the pump is running. I'm going to do this by measuring the current flowing in the power cable to the pump. That seems like it ought to be an easy thing to do, but doing it safely (it's a 240V AC mains cable to the pump) and reliably is more complicated than I expected. There might be a simpler way to do things than what I'm trying to do, but this is a good opportunity to do a little bit of analogue electronics and to learn some things. (My analogue electronics skills are negligible, so I'm always on the lookout for small projects or parts of projects that have the right "challenge level" to help me get better!)

We live on the side of a hill where rainwater runs down into our garden, gathering at the lowest point to make a "sumpy" patch. The soil has a high clay content, so the runoff is efficient. We also have a cellar. (You can see where this is going already, right?) We have a shaft next to the house that contains a pump to clear out water draining into the sumpy area. A couple of months ago I took the lid off the shaft and found the pump under two metres of water, not running. Opening up the stairs down to the cellar revealed half a metre of water down there... Not good.

Kolyma is a region in the far east of Russia. It's brutally cold, sparsely vegetated, mostly covered in permafrost, and has huge mineral reserves. It was a "favourite" destination of convicts in the Soviet penal system.

I'd not even really heard of the place until a few months ago, but since then I've read two books set in Kolyma. Two very different books, one a modern thriller and one something completely other.

In this final article of three, we're going to make our DMA-based ADC example from the second article run off a timer, and we'll do a small demonstration of how this might be used in a realistic application.

There's a video demonstrating each of the examples covered in this series of articles. It's probably most useful to watch it in conjunction with reading the articles.