Analysis of OUTPUT high GPIO in suspend / DL_GSM
joerg at openmoko.org
joerg at openmoko.org
Sat May 10 16:00:18 CEST 2008
Am Sa 23. Februar 2008 schrieb Andy Green:
> > [ 58.325000] GPJ06: OUTPUT 1 <== DL_GSM... what does it do? ***
> DL_GSM controls a couple of tristate drivers via an active-low nOE that
> are to do with communication to the GSM side as part of an elaborate
> scheme that looks like it can in the fullness of time just be replaced
> by DL_GSM and one other IO under a FIQ GPIO UART implementation,
> removing R4403, U4401 and doing it all from the CPU side.
> R4403 (100K to 0V connected to DL_GSM) means we burn 33uA / 108uW by
> having OUTPUT 1 in suspend ... hey it all adds up. However setting it
> OUTPUT 0 or allowing it to float so R4403 controls it means this dual
> tristate driver (always-on BTW) is enabled to drive unknown levels into
> bad places.
Make R4403 NC!
If we need R4403 for fab, kill it after flashing GSM-module.
Booting with headset connected, uBoot gives those bad deafening chirps and
clicks. (don't do this at home!! Will OM pay for my hearing aid? For any
The tristate drivers of U4401 are active by default when CPU is reset, due to
I *strongly* recommend to make R4403 NC. So we have a chance GPIO DL_GSM is
high Z at CPU-reset and U4401 blocks TX-IRDA to aerjack path.
This should be a pullUP, no pullDOWN!
ps: there are other very strange issues like
O- after boot, left earpiece(!) is microphoning to right earpiece when tapping
it with a finger (no that's not the mic and ALSA settings! That's left
O- Sound only by left earpiece?
- Left earpiece *gets hot* during boot????
Will have to check more detail on these issues.
O-(!!) [hw] Using headset for a call is completely useless, GSM RF feeds into
mic _really_load_ so you don't hear anything else (missing RF block measures
on earjack receptacle). Maybe can fix with a ferrite block near jack on
headset cable? (compare charger for what I'm talking about)
O- [sw?] Headphone (earpiece_l) and device speaker SPK4102 are mutually
exclusive. (Alas this is NOT headset and _device_earpiece_ are alternative)
We can not disable headphone, so we mustn't activate speaker(-mode) of
U4101-amp when headset connected. What about ringtone playback while headset
used device: Prototype GTA02-113.
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