LisaList2

Quote from: sigma7 on August 23, 2026, 08:44:09 PM

Quote from: AlexTheCat123 on August 23, 2026, 06:53:54 PMPerhaps @sigma7 can tell us what he used to successfully power up his Twiggy drives?

This "atomi AT1080" gets me far enough to boot BLU from the built-in ESProFile, and runs the drive well enough to read...

I noticed that there are a few high-powered USB-C power bricks made for the Raspberry Pi platform, including this one that claims a total output of 27W @ 5A and up to 45W, depending on what device it's connected to. I thought for sure this would supply enough power to run one Twiggy drive.

It did get further along and booted to the LOS 2.x desktop, and read the Twiggy disk that I inserted into the drive. This disk came from an LOS 1.2 machine, so it prompted me to update the disk format. When I affirmed the decision to format the disk, it tried to write to the disk and died as before. Not enough power once again, it seems.

Here's the power adapter I used: https://www.amazon.com/dp/B07H125ZRL

Quote from: ried on August 25, 2026, 04:44:42 PMthis one that claims a total output of 27W @ 5A and up to 45W, depending on what device it's connected to

One of the reviews on the amazon listing says:

QuoteI found out what the issue was. You have to add a line to the config.txt file and rpi-eeprom-config file to tell the Pi5 that it is indeed powered by a compliant PSU. That line is "PSU_MAX_CURRENT=5000".

Which to me means that a USB-C PD current higher than 3A needs to be negotiated by the device... I guess.

Perhaps Alex can have the FPGA negotiate with the power source?

edit: I'm now thinking that it may have been the Pi5 that was limiting the current for that reviewer, not necessarily the supply.

Are you using a cable rated for 5A? Apparently they have some electronics in them that tell the supply if they are capable of more than 3A.

Quote from: ried on August 25, 2026, 04:44:42 PMIt did get further along and booted to the LOS 2.x desktop, and read the Twiggy disk that I inserted into the drive. This disk came from an LOS 1.2 machine, so it prompted me to update the disk format. When I affirmed the decision to format the disk, it tried to write to the disk and died as before. Not enough power once again, it seems.

Well that's progress I guess! It means that the Lisa successfully read the disk's filesystem.

Do you have a bench power supply that you could connect straight to the board instead of using a USB-C cable? If so, set it to 5V, set the current limit as high as you can, and then connect it between any 5V pad on the board and GND. The center leg of the POWER switch would be a great 5V pad to attach it to, because then you'd still preserve the functionality of the switch. That should give you more than enough current to drive the Twiggies.

Quote from: AlexTheCat123 on August 25, 2026, 05:43:11 PMDo you have a bench power supply that you could connect straight to the board instead of using a USB-C cable?

Unfortunately, no.

Quote from: ried on August 25, 2026, 05:46:50 PMUnfortunately, no.

Darn. Well I guess my only suggestion is to keep trying other USB power supplies until you find one that works. I can't really think of anything else to try!

Quote from: sigma7 on August 25, 2026, 04:57:08 PMAre you using a cable rated for 5A? Apparently they have some electronics in them that tell the supply if they are capable of more than 3A.

The cable is part of the power adapter (permanently attached). It's very sturdy, more so than any other USB cable I have.

Quote from: AlexTheCat123 on Yesterday at 02:43:37 AMDarn. Well I guess my only suggestion is to keep trying other USB power supplies until you find one that works. I can't really think of anything else to try!

Just ordered an Anker 140W GaN charger. This one has to work, right?
https://www.amazon.com/dp/B0DFCFTNXM

Quote from: ried on Yesterday at 03:16:06 AMThis one has to work, right?

Of course it does!

For a low-tech alternative I'm wondering about:
https://www.amazon.com/cablecc-Repair-Solderless-Connector-Terminal/dp/B0FY2GW4YN

With something like:
https://www.amazon.com/HPMN-5V-10A-50W-Transformer/dp/B0FQTP9R12
However, some of the random named power adapters I've tested only deliver 1A in spite of being rated 3A or 5A, so maybe Amazon isn't the right place to get such a thing.

This might be more likely to work:

https://www.jameco.com/z/GST60A05-P1J-MEAN-WELL-5-Volt-6-Amp-30-Watt-3-Wire-Regulated-Switching-Desktop-Power-Adapter-2-1mm-Plug-Level-VI_2224358.html

If one is going to assemble something like this, a voltmeter is required to confirm it is correct before connecting it to something valuable like a LisaFPGA.

edit: A preferred power source would be adjustable and display the voltage and current, but those tend to be more than $100 (some much more depending on features).

Quote from: sigma7 on Yesterday at 04:26:07 AMFor a low-tech alternative I'm wondering about:
https://www.amazon.com/cablecc-Repair-Solderless-Connector-Terminal/dp/B0FY2GW4YN

With something like:
https://www.amazon.com/HPMN-5V-10A-50W-Transformer/dp/B0FQTP9R12
However, some of the random named power adapters I've tested only deliver 1A in spite of being rated 3A or 5A, so maybe Amazon isn't the right place to get such a thing.

This might be more likely to work:

https://www.jameco.com/z/GST60A05-P1J-MEAN-WELL-5-Volt-6-Amp-30-Watt-3-Wire-Regulated-Switching-Desktop-Power-Adapter-2-1mm-Plug-Level-VI_2224358.html

If the Anker charger doesn't work, then this would definitely be the next thing to try. It's basically the same thing as my bench power supply idea, but more elegant.

The CanaKit for Raspberry Pi would at least allow the Twiggy disk to be read. The Anker doesn't even get that far. Ugh.

When booting LOS 2.x, the Anker's built-in display indicates around 6W of power being drawn by the USB-C port. When the desktop appears and the Twiggy drive starts to move, the display briefly indicates 10W being drawn, and the LisaFPGA shuts off.

Quote from: ried on Yesterday at 08:12:24 PMWhen booting LOS 2.x, the Anker's built-in display indicates around 6W of power being drawn by the USB-C port. When the desktop appears and the Twiggy drive starts to move, the display briefly indicates 10W being drawn, and the LisaFPGA shuts off.

Yeah, I think @sigma7's suggestion is going to be the only solution here. I had no idea that a single Twiggy would draw so much current!