[Gta04-owner] What is GPIO175 "HOST_WAKE_WWAN" for?

Dr. H. Nikolaus Schaller hns at goldelico.com
Thu Dec 15 08:35:15 CET 2011

Am 15.12.2011 um 08:23 schrieb Dr. H. Nikolaus Schaller:

> Hi Neil,
> Am 14.12.2011 um 22:02 schrieb NeilBrown:
>> Hi,
>> Looking at the schematic there are two GPIO pins connected to the GSM module.
>> 176 "3G_WOE" is apparently for the GSM module to use to wake the CPU when
>> something is happening,
> Yes. It will be moved to the GPIO10 on the A4 board since this will allow to
> power down the GPIO block #6 during sleep.
> The function appears to work and I have committed a simple patch for the
> board file so that a wakeup interrupt is being displayed if you ring up the


(also adds some #define for GPIOs and removes some older stuff)

> device or it receives a SMS or is being reset by AT_ORESET.
>> but what is 176 "HOST_WAKE_WWAN" for?  Is it out from the CPU and IN to the
>> GSM, or the other way?
>> Any hints?
> It is to be used if the module has no USB interface but SPI. The USB interface
> can wake up the module automatically (by USB handshaking). Since we don't
> use SPI this pin has no function. On the GTA04A4 board the SPI interface will
> be removed and GPIO176 will be reassigned (optional keyboard IRQ).
>> And still curious - what is the change made to the later board to make it
>> possible to power-down the GSM module?
> Christoph already wrote: it can control the on/off function which is a power toggle
> mode. In the meantime AT+CFUN=0 and suspending USB should have the same
> effect. Controlling this through the CPU allows to keep the module completely
> disabled while the CPU boots and reduces the power-up energy budget. Until
> the CPU has enabled USB.
> Nikolaus
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