Flashing in General

The only supported method of flashing in DeityGuard is via the FTDI UM232H (datasheet), a breadboard-friendly breakout board for the FTDI FT232H “bridge chip” (datasheet). (Note that it is completely unnecessary to read “datasheets” as long as you follow the instructions on this page precisely; they are only linked here if you want to better understand how everything works).

The UM232H is plugged into a breadboard, and wires are added to configure it and connect it to either:

  • a test clip for in-circuit flashing of the t400 BIOS chip, or:
  • a land area for a DIP-8 chip for flashing of the d16 BIOS chip.

Flashing t400 (Lenovo T400)

Here is the schematic (or rather, “breadboardatic”):

In the schematic, the arrowed wires should lead to a 3.3V power supply (not shown). The teal dot below the clip diagram indicates the side of the clip that should be towards the LCD panel. Once you have assembled it, the most convenient way to connect it is to place the breadboard on the left side of the BIOS chip with the USB port pointing in the other direction from the LCD panel.

Once you have assembled the breadboard, proceed to:

  • unpower the t400 by disconnecting power and battery from the t400
  • connect the Pomona test clip to the t400’s BIOS chip
  • turn on the external power supply
    • if it has a current indicator, it should read about 180mA
  • connect the UM232H to the host computer through USB

Now you are ready to flash from the host system.

Flashing d16 (ASUS KGPE-D16)

Here is the schematic (or rather, “breadboardatic”):

When wiring up the breadboard, bear in mind that some breadboards have the power and ground rails configured differently from the way shown in the diagram. It is recommended to change the wiring to match the breadboard’s indicators. If your breadboard does not have power and ground rails, you can dedicate some unused rows for this purpose.

The default BIOS chip in the d16 has a capacity of only 2MiB. After unpowering the d16, remove the default BIOS chip carefully (in order to not damage the socket) and solder a 4MiB SOIC chip onto a SOIC-to-DIP adapter.

Using gold-plated machine pins has the advantage that the assembly can be inserted and removed from the socket with great ease compared to a normal DIP chip, and the gold plating ensures good electrical contact despite the smaller contact area.

Once you have assembled the breadboard, proceed to plug the BIOS chip into the landing area on the breadboard and you are ready to flash from the host system.

Flashing bpi (Banana Pi)

Not necessary! Firstly, the Banana Pi has no BIOS chip; the SoC’s boot ROM has enough smarts to load the bootloader from the SD card. Secondly, it is not recommended to boot from the SD card at all since it is not possible to protect against malicious SD card firmware. Always boot the Banana Pi through USB FEL mode.

Flashing rok (Asus C201 Chromebook)

Allegedly, one must disconnect the battery before flashing this board. To do so, you must unscrew all the screws that hold the heat spreader down onto the motherboard, as the battery connector is under the heat spreader.

Getting the clip connected properly is challenging due to small passive components soldered near the BIOS chip, but getting a good contact can be done reliably with practice.

In the schematic, the arrowed wires should lead to a 3.3V power supply (not shown). The teal dot above the clip diagram indicates the side of the clip that should be towards the LCD panel.