Unfortunately I don't have any soldering tools or experience, so if you could give an advice about ISP programming (In-System-Programming/In-Situ-Programming) , it will be super helpful!
I teardown a bricked laptop, removed AC power, laptop's power battery, and even a small CMOS battery, and now I am trying to write a working BIOS image to laptop's SPI flash chip using a SOIC8 test clip.
But here is a problem: I could read a dump from this BIOS chip without problems, however it fails when I am trying to write - so the contents of BIOS flash chip are remaining unchanged. Luckily I found out this helpful wiki page - http://flashrom.org/ISP , which describes common problems with this ISP method of flashing, as well as gives 3 hints for solution! Sadly this page is currently down, so here is a screenshot: http://i.imgur.com/SJEYHR2.png
1. - tried to make shorter wires, less than 10cm as they recommend - it did not help 2. - soldering is out of possibility, cant do it, and also: wires are already short and they are good quality (pure copper) 3. - This hint looks more promising, but I need help in understanding this piece of information: "disconnect Vcc from the programmer and power it with its normal PSU"
If I understand correctly, by Vcc they mean Vcc pin of the BIOS flash chip. But if I disconnect Vcc from the programmer, what is "normal PSU" which should power this Vcc pin?
Should I connect to motherboard a laptop's power battery, or small CMOS battery, or AC adapter of laptop, so that this Vcc pin would be powered by them, or it is forbidden to do it while using SPI programmer in the same time? Or its better to try to power Vcc of flash chip from "USB to TTL" adapter - which has this 3V3 (3.3V) voltage pin?
Yours faithfully, Robert Brown
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Hi Robert,
it might be easier to help if we knew your Laptop model. Also, please provide a full log of the failing flashrom run with the -V switch, you can specify a log file with -o.
On 17.10.2015 02:07, Robert Brown wrote:
But here is a problem: I could read a dump from this BIOS chip without problems, however
Please further define "without problems". Did you try several reads and compared the contents?
it fails when I am trying to write - so the contents of BIOS flash chip are remaining unchanged.
Log please. By guessing two possible issues come in mind: 1. Your pro- grammer doesn't provide enough power for erasure. 2. The write protec- tion pin of your flash chip is asserted.
Should I connect to motherboard a laptop's power battery, or small CMOS battery, or AC adapter of laptop,
I'd try with the AC adapter. In that case Vcc must _not_ be connected to your programmer. GND, OTOH, has to stay connected.
so that this Vcc pin would be powered by them, or it is forbidden to do it while using SPI programmer in the same time?
Not forbidden. It's sometimes even encouraged because there are boards where the Vcc pin of the flash chip is directly connected to other chips, which would draw down the power from the programmer.
Or its better to try to power Vcc of flash chip from "USB to TTL" adapter - which has this 3V3 (3.3V) voltage pin?
It really depends on your machine.
Nico
On Sat, 17 Oct 2015 12:57:54 +0200 Nico Huber nico.h@gmx.de wrote:
- The write protection pin of your flash chip is asserted.
That's what I suspect too, but it could also be some other sort of write protections. Some chip do support more flexible ways of write protecting the chip, that's for instance used in the chromebook where, if I understand correctly, only a region of the chip is protected (like 2MB/16MB for instance).
I should check the datasheet mentioned previously. I'll look briefly if the issue is not resolved.
Robert, since the laptop is bricked anyway and that you already have backups of the flash, you could try to erase the chip with "flashrom --erase" and then dump the content of the chip again. That way you could more easily see which zones have been erased, and which haven't. Also please attach the log next time.
Also, I'm not used to all the issues related to powering the laptop on or not, I never took the time to look that up. Do you have a multimeter to investigate such issues? If so you could check the voltages at the chip pins (to verify if any drop is occurring), you could also check the value of pins like WP# (write protect).
On Sat, 17 Oct 2015 12:57:54 +0200 Nico Huber nico.h@gmx.de wrote:
I'd try with the AC adapter. In that case Vcc must _not_ be connected to your programmer. GND, OTOH, has to stay connected.
If that happens, could the EC be destroyed? or the laptop power system? I've a laptop that doesn't lit its leds once a power supply is connected to it. I broke it while messing with reflashing after trying to test ME related stuff on it.
On Sat, 17 Oct 2015 12:57:54 +0200 Nico Huber nico.h@gmx.de wrote:
so that this Vcc pin would be powered by them, or it is forbidden to do it while using SPI programmer in the same time?
Not forbidden. It's sometimes even encouraged because there are boards where the Vcc pin of the flash chip is directly connected to other chips, which would draw down the power from the programmer.
Robert, I think it can be detected by measuring the voltage at the pins of the SPI programmer before and after plugging the clip. Nico, Are there other common issues of the same kind with laptops?
Denis.
On 22.10.2015 00:24, Denis 'GNUtoo' Carikli wrote:
On Sat, 17 Oct 2015 12:57:54 +0200 Nico Huber nico.h@gmx.de wrote:
I'd try with the AC adapter. In that case Vcc must _not_ be connected to your programmer. GND, OTOH, has to stay connected.
If that happens, could the EC be destroyed? or the laptop power system? I've a laptop that doesn't lit its leds once a power supply is connected to it. I broke it while messing with reflashing after trying to test ME related stuff on it.
It's more likely to break a power supply. If you connect different Vcc sources you might get a current flowing in the wrong direction at the weaker source.
On Sat, 17 Oct 2015 12:57:54 +0200 Nico Huber nico.h@gmx.de wrote:
so that this Vcc pin would be powered by them, or it is forbidden to do it while using SPI programmer in the same time?
Not forbidden. It's sometimes even encouraged because there are boards where the Vcc pin of the flash chip is directly connected to other chips, which would draw down the power from the programmer.
Robert, I think it can be detected by measuring the voltage at the pins of the SPI programmer before and after plugging the clip. Nico, Are there other common issues of the same kind with laptops?
Doing ISP on a board that's not designed for ISP gives issues all over the place. Most can be worked around with very low clocks and a good power supply. But if you get reliable reads, writing usually works too (if there's no write protection).
Nico
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Denis 'GNUtoo' Carikli -
Nico Huber -
Robert Brown