[Gta04-owner] AS3935 in GTA04?

Dr. H. Nikolaus Schaller hns at goldelico.com
Mon Apr 14 22:51:41 CEST 2014


Am 14.04.2014 um 22:20 schrieb Andreas Kemnade:

> Hi,
> 
> On Mon, 2014-04-14 at 08:11 +0200, Dr. H. Nikolaus Schaller wrote:
> 
>>> If I manage to integrate it into the gta04 I will send some photos.
>>> Is it possible to let the gta04 wake up from suspsend when the sensor
>>> gives an interrupt if it is integrated into the gta04 case?
>> 
>> Yes, if you can connect the interrupt to the KEYIRQ input.
>> 
>> One other thing to consider: it looks as if you need a 1.8V to 3.3V
>> I2C level shifter (TXB0201) and another one for the interrupt (unless
>> it is an open drain output).
>> 
> Hmm, IMHO I could connect that chip to a 2.5V power source (vaux1?),

Yes, VAUX1 is spare and intended for such use.

One general hint: please use very very thin copper wires if you solder directly
to the test points or you easily may rip them off by pulling on the cable. And
then there is no chance to repair them. This is the reason why we plan a
FFC connector for the GTA04A5.

A better place for connecting wires is to locate some R's or C's on the PCB.

> check whether it does not pull up the the I2C lines itself (which would
> violate i2c), and then it should work without level shifter. The irq is
> active high, maybe I can just add a voltage divider.

Yes, that should work well.

> Google does not know about that level shifter. It the part numbe really
> correct.

Sorry: I meant TXS0102. Ther is also a TXB0104 but it is not for open collector.

> 
> Considering the space: I have 27mm x 9mm (next to the battery).
> in that area. The antenna coil in the breakout board is 11.7x3.5mm
> It could work.

Yes, that looks fine :)

BR,
Nikolaus



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