libreboot
/
lbwww
1
0
Fork 0
Code Packages Projects Releases Activity

w541: clarify notes about chip select 

Signed-off-by: Leah Rowe <info@minifree.org>
master
Leah Rowe 2024-08-18 01:26:14 +01:00
parent f1151c0f3e
commit b7c7fd53e4
1 changed files with 9 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
site/docs/install/w541_external.md
View File

@ -92,8 +92,8 @@ pin 1.
When you wire the clip, to flash one of the ICs, the same voltage rail also
turns on the other IC and the other IC's own chip-select is in a *floating*
state, which in practise means *high logic state*; in other words, the other
flash will be active.
state, which in practise means *random logic state*; in other words, the other
flash may or may not be active, randomly.
This means that external flashing would not ordinarily work, unless you use
the following trick:
@ -105,6 +105,13 @@ on pin 8 of the chip that you're flashing. Ideally you should pull the other
chip select high via 47ohm resistor, which should be enough to prevent damage
in the case of accidentally shorting the wrong pin.
Doing this means that you *disable* the chip fou're not flashing. It's very
important that you ensure only the one you want to flash is active, when using
an external flasher.
**This is not required for internal flashing. It is only required for
external flashing.**
If you do it right, the chips should flash reliably. This same trick must be
used when flashing either of the chips.