NAND vs SD on GTA02

Michael Sokolov msokolov at ivan.Harhan.ORG
Tue Sep 27 09:23:17 CEST 2011

Gennady Kupava <gb at> wrote:

> Interesting point. I noticed that all my last GSM failures with GTA were
> related to simple fact that CPU itself were working, but GSM do not
> because simple battery discharge. 

The set of Calypso docs I have found and put up on my FTP site (see the
other thread) includes a spec for the Iota chip.  Iota is the Analog
Baseband (ABB) component of the chipset, but it also handles power
management.  The Iota spec says the minimum battery voltage is 3.0 V.
The Rita chip (RF transceiver) also draws some power directly from the
battery without going through the Iota, and its spec also says 3.0 V is
the minimum.  That voltage appears to be the design minimum for
Calypso/Iota/Rita phones.

In comparison, the PCF50633 which provides power management to the AP
(application processor) part of the GTA02 claims to be able to handle
Vsys going down to 2.8 V.  Hence the Calypso/Iota/Rita block appears to
be the limiting factor for how low you can drain the battery and still
keep the phone functional (as a phone).

> Use NAND.

Yup, that's my plan.

> If it wears out in few years, you can just buy one more GTA02
> cheap as dirt.

Hmm, I wouldn't call $468.46 USD (what I've paid for my GTA02 order,
after EUR currency conversion, shipping and international bank transfer
fees) exactly dirt cheap.

> Also you can switch to uSD at any time, so if you NAND
> will fail, you can just start using uSD.

Yes, very true.

> I hope anyone interested can buy GTA04 soon, so no need to worry about
> GTA02 stock.

For some of us GTA02 is a lot more valuable than GTA04!  Am I really the
only person left in the world who wants his phone to be a PHONE, not a
handheld computer, not a PDA, not a Wifi toy and not a GPS navigation
device?  For a phone that acts as a *phone*, i.e., stays registered with
the cell network while drawing the smallest possible amount of power
from its battery, receives incoming calls and SMS on its assigned PSTN
number, and allows its user to make outgoing calls and SMS, the part
that matters the most is the GSM baseband processor.  The whole Linux-
based application processor becomes essentially superfluous fluff for a
basic phone.

For someone who wants his phone to be a phone, "free your phone" means
freeing the GSM baseband processor, nothing less.  With the leaked/
liberated Calypso bits I've been finding on that Chinese forum site
(hoping to find more...), there is now at least a glimmer of a possibility
of freeing a Calypso-based phone down to the GSM RF level.  But I don't
see how anyone would be able to do that with a "modern" fully-monolithic
UMTS module (GTA04 style) any time soon.


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