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thoUART t480 

Signed-off-by: Leah Rowe <info@minifree.org>
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Leah Rowe 2024-12-29 15:12:25 +00:00
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1 changed files with 14 additions and 27 deletions
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site/docs/install/t480.md
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@ -356,40 +356,27 @@ the Fn keys for it don't currently work, as of 6 December 2024.
You can set the backlight manually, or use a hotkey, depending on your window You can set the backlight manually, or use a hotkey, depending on your window
manager or desktop environment. manager or desktop environment.
UART UART (T480 only. Not T480S)
---- ----
To our knowledge, this functionality is *only* available in coreboot-based **NOT supported on the S model (T480s). Please only do it on a T480.**
firmware such as Libreboot. It is completely unsupported on the original
firmware!
A serial console is possible via the line-out (headphone jack). Not yet tested The EC on ThinkPad T480 has a UART available, and it is enabled in coreboot,
on the T480s (S model), nor implemented, but it is working on the regular as used by Libreboot. However, you must use a *specific* EC firmware version.
T480 (non-S model). Please read notes elsewhere in this page regarding Lenovo UEFI/EC BIOS updates;
an exact version number is referenced, which you must install prior to Libreboot
installation.
**TODO: show photo and wiring diagram here.** Ways to flash the EC firmware from Libreboot have not yet been established. Now,
please observe the following photo:
Use baud rate 115200 in your favourite serial terminal client, e.g. GNU Screen. <img tabindex=1 alt="ThinkPad T480 UART jumpers" class="p" src="https://av.libreboot.org/t480/t480uart.jpg" /><span class="f"><img src="https://av.libreboot.org/t480/t480uart.jpg" /></span>
Next to the headphone jack on the T480, you will find pads for two 0ohm jumpers, You will solder zero-ohm jumps on the indicated footprints. These correspond
normally unpopulated, but you can bridge each jumper yourself using a 0ohm 0201 to TX and RX, which are connected to the R and L lines on the headphone jack,
jumper; alternatively, simply strip a bit a wire (30awg solid core) and carefully respectively; a ground will also be available.
solder the wire across each of the pad jumpers, then carefully using a pair
of side cutters to cut off the excess wire, being careful not to rip the pads!
If you do this, please make sure to have the latest EC firmware as of 5 You can hook this up to any 3.3v TTL UART dongle, to get a serial console.
December 2024 (do not use older than what was latest on this day, and don't
use newer versions), because the code for this in coreboot targets a specific
area of code within the EC firmware.
You can then wire a 3.5mm stereo plug. On the other end you will wire your
TX/RX lines as you wish, to a suitable UART adapter; any 3.3v-rated TTL
adapter should work. The Raspberry Pi Pico can be used for this, which is handy
because that can also be used as a serprog-based NOR flasher!
The T480s (S model) schematics is a bit different and the signals are
properly muxed. Note that this is not to be confused with `spkmodem`, which
has not been tested on these boards (but could theoretically be possible too).
Idea for 2nd NVMe mod Idea for 2nd NVMe mod
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