[coreboot] your preferred method for supplying power to chip for RPi spi flashing?

[Zoran Stojsavljevic]

> Now I always unplug the AC adapter and remove the battery before
> powering up my flasher (although I do leave the chip-clip connected).

This is about right. I programmed most of INTEL platforms using dediprog
SF100: ATOM: from D4xx/D5xx (Pine Creek) series, TNC, BYT-M/I, BSW and CORE
(IVB, HSW, BDX-DE, BDW-H, SKL-Y/U), whereas for some HSW-U series it was
necessary to put platform in S5 state by shutting down them to S5. AC in
most cases removed, I did not have battery since I played with test
platforms. And there were 4x2 pins connectors for most of platforms,
recently with special small connector forms and adapters for SF100
programming heads, but in some cases I needed clip to connect directly to
flash.

Zoran

On Thu, Dec 1, 2016 at 3:02 PM, Trammell Hudson <hudson at trmm.net> wrote:

> On Thu, Dec 01, 2016 at 01:15:59PM +0000, Peter Stuge wrote:
> > Michael Carbone wrote:
> > > I have been attempting to use a raspberry pi for spi flashing and when
> I
> > > use the 3.3v pin the raspberry pi doesn't power up as the chip draws
> too
> > > much power through the 3.3v pin for the raspberry pi to also run.
> >
> > It's not the flash chip drawing current, it's the rest of the mainboard.
>
> For some mainboards (like the 15" 2014 Macbook Pro) I had to add a 1-10
> Ohm resistor on the power lead from my flasher, which basically glitches
> the rest of the mainboard, but since many SPI flash chips can run at
> a slightly lower voltage it allowed me to read/write the firmware.
> This is probably not the right way to do it.
>
> > [...]
> > > Looking online [1] some folks recommend using laptop AC adapter +
> > > wake-on-lan (and not using the VCC/3.3v pin), but I'm not sure
> > > that's a dependable strategy
> >
> > In fact I consider it the *only* dependable strategy. It is the
> > obvious way to adhere to the required power up sequence.
>
> I've never had success with this technique due to the multi-master
> situation that you described.  The PCH (or ME?) on modern CPUs
> seemed to always be driving the IO lines when I provided power.
> Now I always unplug the AC adapter and remove the battery before
> powering up my flasher (although I do leave the chip-clip
> connected).
>
> Perhaps I'm a little more YOLO with many of my test machines than
> is prudent, so I don't worry too much about what other bits are being
> powered up by the 3.3V rail.  On the x230 I used an external bench
> supply and found that the rail needed about 110 mA to function:
>
> https://www.flickr.com/photos/osr/28494632165/lightbox
>
> So on my teensy 2 flasher I replaced the small SMD regulator with
> a larger UA78M33 regulator in a TO-220 package that can supply 500mA:
>
> https://www.flickr.com/photos/osr/30531707094/lightbox
>
> My biggest problem these days is that the chipclips seem to wear out
> after a few hundred applications (the pins get pushed upwards, making
> the connection flaky).  Anyone have a recommendation for one that can
> stand up to constant use?
>
> --
> Trammell
>
> --
> coreboot mailing list: coreboot at coreboot.org
> https://www.coreboot.org/mailman/listinfo/coreboot
>
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