SPI Archieven - #Tom's Weblog

I made this post as a addition or supplement to my “Flashing a BIOS chip with an Arduino” post.

While doing some research online I found several articles/posts from people using a Raspberry Pi to flash SPI flash chips. Apparently the Raspberry Pi is very suitable for this kind of thing as it has a SPI interface and is able to run linux. I was eager to try this out for myself so I got out my Pi 3 model B and got to work. For this project I used a Winbond 25X80 salvaged from a motherboard I had lying around.

Preparing the RaspberryPi

As others have pointed out, the latest version of Raspbian (Stretch) will also work by adding the spispeed param to the Flashrom command.

Enable the SPI interfaces by typing sudo raspi-config and selecting P4 SPI under the Interfacing options.

The SPI interfaces will become available under /dev/spidev0.0 and /dev/spidev0.1.

Next we install the packages are needed by Flashrom by using the following command.

sudo apt install git libpci-dev libusb-1.0 libusb-dev

Make and install Flashrom.

git clone https://github.com/flashrom/flashrom.git cd flashrom make && sudo make install

Connecting the Raspberry to the SPI flash chip

The table below show the connections between the RaspberryPi and the chip.

RPi pin	SPI flash
25	GND
24	CS
23	SCK
21	DO
19	DI
17	VCC 3.3V and /HOLD and /WP

Flashing the chip

In order to verify Flashrom correctly identifies the chip we run Flashrom without any operations.

pi@raspberrypi:~ $ flashrom -p linux_spi:dev=/dev/spidev0.0,spispeed=512 flashrom p1.0-76-g291764a on Linux 4.14.34-v7+ (armv7l) flashrom is free software, get the source code at https://flashrom.org  Using clock_gettime for delay loops (clk_id: 1, resolution: 1ns). Found Winbond flash chip "W25X80" (1024 kB, SPI) on linux_spi. No operations were specified.

Now that Flashrom correctly identifies the Winbond W25X80 we can continue to backup the current BIOS.

pi@raspberrypi:~ $ flashrom -p linux_spi:dev=/dev/spidev0.0,spispeed=512 -r flash.dat flashrom p1.0-76-g291764a on Linux 4.14.34-v7+ (armv7l) flashrom is free software, get the source code at https://flashrom.org  Using clock_gettime for delay loops (clk_id: 1, resolution: 1ns). Found Winbond flash chip "W25X80" (1024 kB, SPI) on linux_spi. Reading flash... done.

After backing up the old BIOS we can safely write the new BIOS back to the chip.

pi@raspberrypi:~ $ flashrom -p linux_spi:dev=/dev/spidev0.0,spispeed=512 -w flash.dat  flashrom p1.0-76-g291764a on Linux 4.14.34-v7+ (armv7l) flashrom is free software, get the source code at https://flashrom.org  Using clock_gettime for delay loops (clk_id: 1, resolution: 1ns). Found Winbond flash chip "W25X80" (1024 kB, SPI) on linux_spi. Reading old flash chip contents... done. Erasing and writing flash chip...  Warning: Chip content is identical to the requested image. Erase/write done.

References:

Testing for some issues with Raspbian Strech

In this post I will explain how to flash bios chips with an Arduino. We will be using a Arduino Duemilnove (uno, mega or clones do also work) and a ASUS P5B motherboard that no longer boots after a failed bios update.

Here is an outline of the steps (some of these steps are not strictly necessary but I figured they might help the uninitiated):

Identify board
Find documentation for the board
Locate and identify bios chip
Find documentation for the chip
Find pinout and operating voltages (important)
Prepare the Arduino
Connecting the Arduino to the chip
Download and install flashrom
Testing
Flashing and verify
Troubleshooting

Identify board and finding documentation

As mentioned in the introduction we are using an ASUS P5B motherboard. The manual of this board can be found on the ASUS website (a direct link can be found in the list of references).

Locate and identifying the bios chip

In the manual we find a board layout that shows the location of the chip, to the right of pci slot 3.

If for some reason the manual does not contain this information we will have to find it ourselves.

Software

VM Player/Workstation (I tried using Virtualbox but for some reason it does not play nice, flashrom will see the chip but will not actually read or write)
An Ubuntu 16 or 18 Virtual Machine
flashrom
fser-duino

The process

Installing git, flashrom and dependencies for frser-duino

sudo apt install git flashrom gcc-avr binutils-avr avr-libc avrdude

Getting frser-duino and preparing the Arduino

git clone --recursive https://github.com/tomvanveen/frser-duino.git
cd frser-duino
make ftdi
sudo make flash-ftdi

Connecting the Arduino to the SPI chip

The following image is an example schematic taken from the flashrom GitHub and shows the pins on the Arduino and the pins on the chip they should connect to (please note that PB0 does not have to be connected):

The image below shows the pinout for the MX25L8005:

Please note that different manufacturers might use different pinouts for their chips and you should therefore always check the datasheet for the correct one.

Flashing the SPI chip

To verify that everything is working correctly we first run flashrom without any operations:

sudo flashrom -p serprog:dev=/dev/ttyUSB0:2000000

The output should look like this:

flashrom v0.9.9-91-g0bfa819 on Linux 4.10.0-28-generic (x86_64)
flashrom is free software, get the source code at https://flashrom.org

Using clock_gettime for delay loops (clk_id: 1, resolution: 1ns).
serprog: Programmer name is "frser-duino"
Found Macronix flash chip "MX25L8005" (1024 kB, SPI) on serprog.
No operations were specified.

If the previous command worked as expected we are now ready for our final step. To write the new BIOS to the chip we use the following command:

sudo flashrom -p serprog:dev=/dev/ttyUSB0:2000000 -w [NEWBIOS]

The output should look like this:

flashrom v0.9.9-91-g0bfa819 on Linux 4.10.0-28-generic (x86_64) flashrom is free software, get the source code at https://flashrom.org Using clock_gettime for delay loops (clk_id: 1, resolution: 1ns). serprog: Programmer name is "frser-duino" Found Macronix flash chip "MX25L8005" (1024 kB, SPI) on serprog. Reading old flash chip contents... done. Erasing and writing flash chip... Erase/write done. Verifying flash... VERIFIED.

And that is it. We have successfully flashed a chip using the SPI interface. If you have any questions or feedback about this post please leave a comment below!