[gta02-core] GSM modem [was Re. Status & next milestone for GTA02-core?]

Álvaro Lopes alvieboy at alvie.com
Mon Aug 3 16:01:05 CEST 2009

Dave Ball wrote:
> Werner Almesberger wrote:
>> Dave Ball wrote:
>>> potential alternative to the calypso (option gtm501) has been 
>>> identified, though we don't yet know for sure that we can use it.
>> By the way, there may be a third possibility for telephony: the
>> Telit GE865-QUAD GSM module:
>> http://www.telit.com/en/products/gsm-gprs.php?p_id=12&p_ac=show&p=11
> I keep forgetting about the Telit :-)  I prefer the option because it's 
> smaller (I don't like the idea of filing down plastics to get a larger 
> module to fit), it's 3G and newer.

I'll be honest here. Even at "typical" consumption the Option chip seems to draw up to 1.1A @ 3.6V. This is completely absurd for a mobile device. We draw at
most 2.5W from USB (500mA at 5v). Chip consumes 3.96W. Completely absurd. I did not find anything about "idle" consumption.

> Having said that, the Telit does have a UART interface (where the option 
> appears to be USB only) - so should be easier to fit into our existing 
> design.

True, but USB is less error-prone, less sensitive to EMI.

> I get the impression that the calypso isn't going anywhere, so how about 
> getting started with Telit based schematics while we're waiting to find 
> out if the Option is a goer or not?

I'm with you Dave.

As long as we can get the schematic "non-intrusive", meaning it does not require changing the already drawn ones.


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