Notices by Attie Grande (attie@chaos.social)

I have an old box for Gigabit Ethernet over free space optical (FSO) link.

The model number and company don't appear to exist on the internet, the very-thin documentation (2 sheets) references what appears to be a private residence near Newbury (UK), and is dated 2004 ish. It's heavy metal box is not 19" but eyeball suggests 1U high, and claims to have been built in Russia.

Sadly I don't have the optics part or the counterpart.

Anyone be interested in seeing the insides, possibly in a video?

Once I've had a rummage inside (because I'm curious), it's free to anyone in the UK who may also be interested.

It was offloaded on to me by a colleague after a FSOC project I was involved with recently, but this box operates at a much reduced distance and is intended for fixed point-to-point communication only.

These f**king plugs with USB adapters in that screetch at you all night long with no way to turn them off. 👎

And there were THREE in the room!

I usually make hotels work as best I can, but this was one thing too much after a long (long) day.

@penguin42 I'm sure, but I didn't have three worthy loads with me! 😭

> If you have difficulty reading emails, or do not have regular internet access, you may benefit from your application being converted to “Assisted Digital”. This would mean that our correspondence with you would be by post.

... uhh ... "assisted digital"?

Do you remember these days?

"Bitcoin could cost us our clean-energy future"

https://grist.org/article/bitcoin-could-cost-us-our-clean-energy-future/

The displays used here are one of my most favourite pieces of optoelectronics ever...

I first saw them on some ultra-expensive rack mount studio equipment while I was working on the BBC Egton Wing refit... and many years later made my wife a silly little scrolling message thingy with 2x 8-character modules (HCMS-3977).

They are *expensive* - I got four, for £37.70 EACH, because I just had to have some. They're £42.48 now...

https://www.youtube.com/watch?v=dBEupkQBFis

@Polychrome Yes, and if you get the band narrow enough then it doesn't sound too terrible! 😂

Biosynthesis by Abiogenesis just came on... and there's this obnoxious tone up at ~15.7kHz

... can we just not please? 😭

I stopped listening... ouch.

@ryanc If you have access to the u-boot console, can you just use that to dump / rewrite the flash?

@ryanc Are you trying to do it in-situ, or did you remove the IC from the board? If it's on the board still, what have you tried? ... e.g: have you tried powering it and holding the main processor in reset (if you can find that signal)

@ryanc Yeah, totally valid imo! I've taken this route with some commercial projects - just allocate a chunk of space and patch in the config on the production line.

@ryanc I saw - a perfectly valid route! 😄

@ryanc @kkarhan Is there no support for using environment variables(?!) ... put the secrets into a .gitignore'd *.env file (or CI variables)... or use the same to produce a header as a pre-build step.

The 32-bit CRC used by Quectel's AT+QFCRC command is a mystery, and there are a handful of unresolved posts on their support forums. I have no idea why this seems to be guarded and isn't in the manual.

So here you go, in case anyone was looking. It seems to be a non-standard configuration of the common polynomial (i.e: Ethernet, Gzip, etc...)

crc width=32 poly=0x4c11db7 init=0x0 xorout=0x0 refin=false refout=false out_endian=big

Thanks delsum!
https://github.com/8051Enthusiast/delsum

Occasionally there comes a time in tracking down a bug, where one eyebrow starts to go up. 🤨

This is one of those moments - the patch below causes the firmware to crash within 2.5 seconds, ~90% of the time. Yay.

The "after" build is 4 bytes smaller due to different assembly output.

... needless to say, two carefully inserted nop instrutions (4 bytes), make everything outside the immediate vicinity align with the "good" sample, and cause the "broken" version to work fine... 😭

This *stinks* of an issue I had a while ago, needing an extra wait-state... the processor was near the edge of a voltage-defined boundary declared by the manufacturer.

https://box.agsys.io/hardfault.html

Unfortunately, it seems to be set correclty in this case.

tmux paired with a quick script is paying dividends here.

1. Send keystrokes to GDB to restart the firmware
2. Wait 45 seconds
3. Look at the last line from the console output
4. If it looks bad, then flag a failure
5. Repeat

See `tmux send-keys` and `tmux capture-pane`