Okay, Al. That's one of the most sensible replies on this thread; I hear ya. I'll dig deeper into this.
Al Johnson wrote: > On Monday 15 December 2008, Karthik Kumar wrote: > >> On Mon, Dec 15, 2008 at 5:35 AM, Stefan Monnier >> >> <monn...@iro.umontreal.ca> wrote: >> >>>>>> There are still hardware problems that exist with almost every >>>>>> freerunner out there (GPS signal levels, for one). I would like to >>>>>> see them fixed by Openmoko, Inc. >>>>>> >>>> The kernel fix for GPS is a mere quirk. Ideally it should get fixed in >>>> hardware. >>>> >>> Huh? The kernel fix seems to work OK for those people who have old >>> FRs. Newer FRs have a hardware fix. E.g. my FR doesn't need any >>> kernel workaround. No need to wait for GTA03 to get a hardware fix. >>> >> So, this kernel fix is a feature, according to Al Johnson? Then why do >> they need a hardware fix? >> > > They don't. Neither of my Freerunners has the hardware fix, and the GPS works > just fine with any kernel that includes the fix. > > >> Unless I am missing something, this software >> fix seems to be a lie. Or the hardware fix seems to be bogus anyway. >> > > You are missing something, so I will try to explain. The 'hardware fix' is a > small capacitor from the SD clock line to ground, and was a quick response to > the problem when the SD was discovered to be interfering with the GPS. This > slows the transition between the digital high and low states, reducing the > level of interference generated. Reducing the drive strength does the same > thing, but through a slightly different mechanism, and doesn't require a > soldering iron to make the change. Note that the hardware fix only reduces > interference from the clock line. The kernel fix reduces interference from > the other signal lines too. > > To understand the issues more fully I suggest you read up on the analogue > properties of digital electronics, particularly in regard to the speed of > transitions and their effect on EMI. > > >> I have one of the earlier freerunners released, so I'm sure Openmoko >> owes an explanation. >> > > Both hardware and software fixes were discussed extensively on the lists, and > are in the list archive. > > _______________________________________________ > support mailing list > support@lists.openmoko.org > https://lists.openmoko.org/mailman/listinfo/support > > _______________________________________________ support mailing list support@lists.openmoko.org https://lists.openmoko.org/mailman/listinfo/support