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diff --git a/doc/supported_hw/supported_prog/serprog/arduino_flasher_3.3v.rst b/doc/supported_hw/supported_prog/serprog/arduino_flasher_3.3v.rst new file mode 100644 index 000000000..0f4b76cbc --- /dev/null +++ b/doc/supported_hw/supported_prog/serprog/arduino_flasher_3.3v.rst @@ -0,0 +1,237 @@ +==================== +Arduino flasher 3.3v +==================== + +Introduction +============ + +This explains how to: + +* Easily lower the voltage of an arduino +* Use that arduino to flash a coreboot image on a GM45 Thinkpad with a SOIC16 chip + +It requires: + +* An AVR Arduino at 5v +* An USB<->Serial adapter capable of providing enough current to power up: + + * The arduino + * The flash chip + * The circuits around the flash chip + +It was tested with: + +* An Arduino.org "nano version 3.3" +* A Sparkfun "FTDI Basic 3v3" (Uses an FTDI FT232R) + +Caveats and warnings: + +* It requires you to to never connect an USB cable between the Arduino USB port and the computer while the flasher is connected to a flash chip. + This would result in the I/O voltage being 5V instead of 3.3V. If you think you may accidentally connect it this way, this flasher isn't the right solution for you. +* You need to read the tutorial, if you don't understand it, it's probably not for you. In doubt you could ask for some help in flashrom real-time channels + or on the mailing list, see :doc:`/contact`. +* For now it requires to patch frser-duino + +Theory +======== + +In the `Atmega328/P datasheet <https://web.archive.org/web/20181004225154/ww1.microchip.com/downloads/en/DeviceDoc/Atmel-42735-8-bit-AVR-Microcontroller-ATmega328-328P_Datasheet.pdf>`_, +the "32.3. Speed Grades" chapter describes (pages 368 and 369) the link between maximum frequency of the microcontroller and the voltage. At 3.3v, the maximum frequency is 12Mhz. + +HOWTO +======== + +Build the code installing it on the arduino +------------------------------------------- + +Building frser-duino +^^^^^^^^^^^^^^^^^^^^ + +First download frser-duino:: + + $ git clone --recursive https://github.com/urjaman/frser-duino.git + $ cd frser-duino + +Then modify the ``F_CPU`` value in ``main.h`` to be 12Mhz instead of 16Mhz. ``F_CPU`` will look like that:: + + #define F_CPU 16000000UL + +Change it to:: + + #define F_CPU 12000000UL + +You can then build the code:: + + $ make ftdi + +Installing the code on the arduino +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Before installing the code on arduino we want to make sure that we are talking to the right device. +To do that make sure that the arduino is not connected to your computer and run:: + + $ ls -l /dev/ttyUSB0 + +If everything went fine it will output something like that:: + + ls: cannot access '/dev/ttyUSB0': No such file or directory + +If instead it looks like that:: + + crw-rw---- 1 root uucp 188, 0 27 févr. 14:30 /dev/ttyUSB0 + +then something else is connected to your computer at ``/dev/ttyUSB0``. If you can't figure what's going on by yourself, +it's better to try get help on the flashrom channels to fix the issue, see :doc:`/contact`. + +Then connect your arduino to the computer and run the same command:: + + $ ls -l /dev/ttyUSB0 + +This time it's supposed to output a line that looks more or less like that:: + + crw-rw---- 1 root uucp 188, 0 27 févr. 14:30 /dev/ttyUSB0 + +At this point we're pretty confident that ``/dev/ttyUSB0`` corresponds to the arduino, so we can install the code with:: + + $ make flash-ftdi + +Once it is installed we can now test that everything went fine with:: + + $ flashrom -p serprog:dev=/dev/ttyUSB0:2000000 + +This will make flashrom talk to the arduino to verify if everything is fine up to this point. + +If everything went fine it will look more or less like that:: + + $ flashrom -p serprog:dev=/dev/ttyUSB0:2000000 + /sys/firmware/dmi/tables/smbios_entry_point: Permission denied + /dev/mem: Permission denied + /sys/firmware/dmi/tables/smbios_entry_point: Permission denied + /dev/mem: Permission denied + flashrom v1.0 on Linux 4.15.2-gnu-1 (i686) + 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" + serprog: requested mapping AT45CS1282 is incompatible: 0x1080000 bytes at 0xfef80000. + No EEPROM/flash device found. + Note: flashrom can never write if the flash chip isn't found automatically. + +This is the important line:: + + serprog: Programmer name is "frser-duino" + +It means that flashrom is able to talk to the flasher, which reports itself as "frser-duino" We also have the following line:: + + No EEPROM/flash device found. + +which tells that it didn't find any flash. This is what's supposed to happen since we didn't connect any yet. + +Build the programmer +-------------------- + +Connect the programmer to the USB<->Serial adapter +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +To do that: + +* Connect the FTDI adapter RX to the TX of the arduino +* Connect the FTDI adapter TX to the RX of the arduino +* Connect the 3V3 of the FTDI adapter to the 5V pin of the Arduino +* Connect the GND of the FTDI adapter to the GDN of the arduino. + +Here's a summary of the above: + +======== ========================= +Arduino USB<->Serial port adapter +======== ========================= +RX TX +TX RX +5v 3.3v +GND GND +======== ========================= + +You can now check that the programmer is responding with:: + + flashrom -p serprog:dev=/dev/ttyUSB0:2000000 + +Since you didn't connect yet a flash chip, it will says it found no flash chips:: + + $ flashrom -p serprog:dev=/dev/ttyUSB0:2000000 + /sys/firmware/dmi/tables/smbios_entry_point: Permission denied + /dev/mem: Permission denied + /sys/firmware/dmi/tables/smbios_entry_point: Permission denied + /dev/mem: Permission denied + flashrom v1.0 on Linux 4.15.2-gnu-1 (i686) + 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" + serprog: requested mapping AT45CS1282 is incompatible: 0x1080000 bytes at 0xfef80000. + No EEPROM/flash device found. + Note: flashrom can never write if the flash chip isn't found automatically. + +Again like before the important parts are:: + + serprog: Programmer name is "frser-duino" + +And:: + + No EEPROM/flash device found. + +If you made it up to this point, you successfully built the flasher. + +Using the programmer +-------------------- + +Connect the programmer to a flash chip +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Since the flasher has been built, you probably want to use it. + +If you use a clip (Like a SOIC-8 or SOIC16 Pomona clip), connect it to the Arduino +Connect the chip to the clip, or if you don't use a clip, the chip to the Arduino +Here's how to connect the flash chips to the programmer: + +=========== ========================== =================== ===================== +Arduino pin Function Flash chip pin name SOIC16 Flash chip pin +=========== ========================== =================== ===================== +D13 CLK (Clock) CLK 16 +D12 MISO (Master In Slave Out) MISO or SO 8 +D11 MOSI (Master Out Slave In) MOSI or SI 15 +D10 CS# (Chip Select) CS# or CS OR SS 7 +GND GND (Ground) GND 10 +5V 3.3V VCC 2 +5V 3.3V WP# (Write Protect) 9 +5V 3.3V HOLD# 1 +=========== ========================== =================== ===================== + +Then connect an USB cable between the USB<->Serial adapter and the computer. +Never connect the cable between the Arduino USB port and the computer while the flasher is connected to a flash chip. +That would result in the I/O voltage being 5V instead of 3.3V. + +Flashing +^^^^^^^^ + +Run flashrom like that:: + + flashrom -p serprog:dev=/dev/ttyUSB0:2000000 + +With some models of Macronix flash chip (that are present in the Thinkpad X200) you might need to add ``spispeed=100k`` like that:: + + flashrom -p serprog:dev=/dev/ttyUSB0:2000000,spispeed=100k + +Thanks +======== + +Thanks a lot to SwiftGeek on IRC (#libreboot on Libera) for finding the first workaround to make it detect flash chips at lower voltage. +Thanks also for telling me about the Macronix issues on the Thinkpad X200. This project would not have been possible without that. + +Page license +============ + +This page is available under the following licenses: + +* `CC-BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0/legalcode>`_ +* `CC-BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0/legalcode>`_ or later +* `GFDL 1.3 <https://www.gnu.org/licenses/fdl-1.3.txt>`_ or later |