GPS rework: Please test and report on software fix prior to attempting any hardware fix

[-stacy]

Al Johnson wrote:

> 
> For a bit more consistency of timing, less manual intervention, and enough
> readings to get an idea of the run to run variation in that location, can I
> suggest a script? It could do with a timeout when waiting for a fix since
> with deivestrength 3 and idleclk 1 this can take a _very_ long time, possibly
> forever in some locations!

I was just about to write a similar script when I saw yours hit my 
inbox... other than a couple of assumptions, I like yours better than 
what I had in mind

> #!/bin/sh
> PASSES=10
> TTFF=""
> 
> get_ttf() {
>   echo "1" > /sys/bus/platform/devices/neo1973-pm-gps.0/pwron
>   TTFF=`(time grep "GPRMC,[0-9\.]*,A," -m 1 /dev/ttySAC1) 2>&1 |grep real`
>   echo "0" > /sys/bus/platform/devices/neo1973-pm-gps.0/pwron
>   echo $DRIVESTRENGTH $IDLECLK $TTFF
>   sleep 20
> }

You assume that the gps is already off, you should either check that the 
gps is off or just turn it off

> echo d i time
> until [ $PASSES -eq 0 ]
> do
>   for DRIVESTRENGTH in 0 1 2 3
>   do
>     for IDLECLK in 0 1
>     do
>       #echo testing drive strength $DRIVESTRENGTH and clock idle $IDLECLK
>       echo $DRIVESTRENGTH > /sys/module/glamo_mci/parameters/sd_drive
>       echo $IDLECLK > /sys/module/glamo_mci/parameters/sd_idleclk

You assume the mount point of the SDCard. Probably a reasonable 
assumption, but I mount mine as /home

>       touch /media/card/gpstest
>       sync
>       get_ttf
>     done
>   done
>   PASSES=$(($PASSES-1))
> done
> 

should likely set drivestrength and idleclk back to default values.

And the results:

d i   min /  avg / max
0 0  35.20/ 55.33/144.30
0 1  37.39/ 77.76/315.76
1 0  33.92/ 38.90/ 41.78
1 1  38.70/ 84.46/151.32
2 0  37.66/ 47.78/108.26
2 1  45.10/120.80/207.08
3 0  36.07/ 42.07/ 47.82
3 1  97.46/173.09/359.69


-stacy