A duck, typing

Logipi Lives!

2 months ago electronics fpga logipi programming raspberrypi

Good news from the resurrecting-dusty-boards-from-the cupboard department: I have managed to get the Logi-pi board to work! The process wasn't too painful:

Resurrecting the Logi-Pi

2 months, 1 week ago amaranth electronics fpga logipi raspberrypi

Way back in 2013, a Kickstarter crowdfunding campaign was launched, aiming to produce an FPGA board that would attach to a Raspberry Pi: the Logi-Pi. Since I was interested in learning more about programming FPGAs, and very excited about the (then very recent) launch of the Raspberry Pi, I supported the campaign, and received a board.

Sadly, for a variety of reasons, that board has sat on a shelf ever since: I didn't even manage to compile the demonstration projects for it! But with my recent interest in Amaranth, I thought it might be a good platform to try out some designs on actual hardware.

So I've dug it out, and will be trying to make it work on recent Raspberry Pi hardware and software. This will present a number of challenges:

When the board was designed, there was only the original Raspberry Pi model B. This had a 26-pin GPIO header, where newer models have a 40-pin header. Though the headers are largely compatible, physical constraints may mean the board doesn't fit newer models so well.
Even if I get the board to fit, the software for talking to the board will need some work: it works by accessing the control registers for the GPIO lines directly. That works fine when there is just one Raspberry Pi model in existence, but now that there are a whole family of them (and the registers are different on different models of the Pi's Broadcom system-on-a-chip) it's preferable to use a library that takes care of all the differences and presents a consistent interface. This will involve rewriting parts of the control software, whose source is fortunately available on GitHub.
I'll have to find somewhere to run the FPGA toolchain. There doesn't seem to be a good open source toolchain for this FPGA (Xilinx Spartan 6 LX9), so I'll need the vendor's multi-gigabyte downloads, plus a beefier machine to run it on than a mere Pi!

Watch this space for progress...

Telescope

3 months, 1 week ago 3dprinting astronomy calibration making telescope

A while back, my son received a birthday present of a telescope: a Chinese-manufactured one, but of reasonable quality - but with no easy way of identifying targets. Since I am very much not an astronomer it proved tricky to train it on anything interesting - even the Moon, a big enough target by any standards, isn't that easy to aim at.

Latchup

4 months, 3 weeks ago amaranth electronics latchup programming python

Latchup leaderboards showing psmears in position 1

I've wanted for quite some time to learn a hardware definition language - that is, a language that can be used to design chips (ASICs) and FPGAs - because this would enable some cool projects. Finally I've found a solution to bridge a motivation gap...

Ferries and Firewalls

7 months, 2 weeks ago firewall irishferries ssh travel

Ferry wi-fi sign

Not long ago we travelled to Ireland on the ferry. The ship's wifi was pretty reasonable quality in terms of speed (it is based on some sort of satellite system) - but it had some curious firewall effects going on. In particular, ssh would sometimes work, and sometimes be blocked (with everything else, including ping to the intended server, working just fine). Annoying - what could I do about it?

Pythonberries

7 months, 2 weeks ago berry polyglot programming python

Berry is a scripting language tailored to embedded devices; in particular it is available on some builds of Tasmota. It has a syntax that is relatively close to that of Python, but not identical. I recently had cause to write the same program in both, which led me to wonder whether it's possible to write one single program that works in both (that is, a polyglot program).

Let's see what that entails...