Re: Power Supply | T400 RPI 2B

[Denis 'GNUtoo' Carikli]

On Tue, 17 Sep 2024 23:37:50 +0000
myrcy@posteo.net wrote:

> Hello everyone,
>          I hope this message finds you well.
> I’m reaching out for assistance with flashing a T400 using a
> Raspberry Pi 2B (at least for now). During the teardown process, I
> came across the following note:
> 
>      > A dedicated 3.3V PSU was used to create this guide, but an ATX
>     PSU is also fine.
> 
> This seems a bit abrupt, as there was no explanation provided about
> why a dedicated power supply is necessary, how to set it up, or where
> to obtain one.
The reason is that it is necessary to power the flash chip, and since
we don't want to desolder the flash chip, if we power it, it also
powers some of the things around it. So it requires more power (mili
ampers) than many single board computer can provide through their GPIO
pins. So the solution is to find a 3.3v line somewhere that does
provide such power.

For the ATX PSU, there is a trick that can power it up without the need
of a computer by connecting two pins together. I don't remember which
pins off hand but I used some metallic paper clip to do that.

> Before I proceed with installing GNU Boot, do I need to purchase a 
> different power supply?
I'm not sure. The lime2 might provide such voltage on one of the pins
already, so if it does, using that makes things much easier.

The problem here is more to understand which pin does that. For the
BealgeBone or the Arduinos, the manual of the board provides such
information.

> If so, does the power supply connect to the 
> machine itself or to the flasher (Raspberry Pi, BeagleBone, etc.)?
You need to connect it to the flash chip somehow.

Denis.

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