GSM power management improvements

joerg Reisenweber joerg at openmoko.org
Fri Feb 15 23:37:05 UTC 2019


On Tuesday, 5 February 2019 02:27:10 CET Mychaela Falconia wrote:
> Hello what's left of Openmoko community,
> 
> If there is anyone still using their FreeRunner (or GTA01) as a phone
> with working GSM (perhaps on a private island whose owner likes GSM
> and is committed to keeping it forever), there is a modem firmware
> update which you might find interesting:
> 
> ftp://ftp.freecalypso.org/pub/GSM/GTA02/gsm-fw/moko-new-fw-20190128.tar.bz2
> 
> The primary diff from previous versions consists of a couple of sleep
> mode improvements, i.e., improved ability to go into sleep modes which
> draw less power from the battery:
> 
> * During those time windows in which the modem is disallowed from going
> into deep sleep by the UART activity timer (10 s after each transmission
> from the AP host to the modem on the AT command UART), previous fw
> versions needlessly suppressed big sleep in addition to deep sleep,
> allowing only small sleep.  The present version goes into big sleep
> during these time windows, saving more power.
> 
> * Some Openmoko devices suffer from a hardware defect that requires
> disabling deep sleep - the infamous bug #1024.  Previous fw versions
> did not provide a sleep mode configuration that allows big and small
> sleep, but not deep sleep, forcing the user to choose between small
> sleep only or big sleep only on no-deep-sleep hardware.  OM AP software
> distros have been using the big sleep only AT%SLEEP=2 config in these
> circumstances.  Our new fw offers a new AT%SLEEP=5 option that allows
> big and small sleep, but not deep sleep, which should be ideal for
> deep-sleep-deprived OM hardware.  The default is still AT%SLEEP=4
> allowing all 3 sleep modes (small, big and deep sleep), just like
> before.
> 
> * Most of the Calypso chip's GPIO and multifunction pins are unused
> and unconnected on Openmoko devices.  All fw versions for this modem
> released prior to 2017, including all legacy mokoN versions produced
> by the now-defunct original manufacturer of the hw, contain a bug in
> this regard: they configure many of these unused and unconnected GPIO
> and multifunction pins as inputs, causing them to float.  The general
> dictum in digital hw design is that CMOS floating inputs are bad, and
> they can sometimes cause increased power draw as a result of current
> flowing through both transistors of the CMOS input structure when they
> are partially open.  This bug has been fixed in the newer FreeCalypso
> fw releases since 2017: the correct way to handle unused and unconnected
> GPIO and multifunction pins is to configure them as dummy outputs with
> a constant value, which is what our current fw does.
> 
> This new firmware release is brought to you by Falconia Partners LLC,
> a manufacturer of new cellular modems under the FreeCalypso brand,
> currently for GSM/2G but perhaps some day for UMTS/3G as well.  At the
> present time we don't do any work specifically for legacy Openmoko
> devices (there is no business case for it), but our own modem product
> is very similar to OM's, thus whenever we make significant improvements
> to the firmware for our own modem hw, it costs us nothing to compile
> and put out a new fw image for Openmoko's old modem as well.
> 
> Please note, however, that even though our new FreeCalypso modem hw is
> very similar to OM's old modem, it is not identical, and the firmware
> images built for the two respective targets are NOT interchangeable!
> We build all of them from the same source tree, thus functional
> improvements made for one target automatically benefit the others as
> well, but a few hardware configuration and external interface bits are
> conditionally compiled.  If you take a firmware image built for our
> FCDEV3B and flash it into an Openmoko device, it may corrupt your FFS,
> so don't do it - please be sure to only flash fw images which were
> built specifically for whichever hardware you have.
> 
> Happy 2019, and enjoy improved power management in the modem if you
> still have a free-running Openmoko device.
> 
> M~
> 
> P.S. In case anyone is concerned about the legality and safety of
> using new GSM products from Falconia Partners LLC, whether our new hw
> or our new fw for legacy hw from OM, please note that the products in
> question (both hw and fw) have been extensively used on public
> commercial GSM networks in several countries (at least USA, Canada,
> Austria, France and South Africa to my knowledge, plus maybe others I
> don't know about) over the course of many years now, without a single
> problematic incident anywhere ever.  Getting an official stamp of
> regulatory approval is definitely in the plans, but no one has paid
> for it yet.  In the meantime, despite having no official rubber stamp
> that says so, we already know with almost 100% certainty that our
> products (both hw and fw) function 100% correctly on the air, fully
> compliant with all of the relevant technical standards.
> 
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Reviewed and considered 100% plausible and without any obvious issues.
Not tested on real hardware though by me.

Many thanks for providing this fine bugfix / improvement firmware

cheers
jOERG
(OM senior EE, hw & synergy)





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