BCM4751 » History » Revision 2

Revision 1 (Paul Kocialkowski, 02/16/2012 07:45 PM) → Revision 2/33 (Paul Kocialkowski, 02/16/2012 08:00 PM)

h1. Broadcom4751GPS 

 h2. Files 

 The non-free files holding the GPS infos/code infos are the following: 

 h2. Protocol 

 Apparently, the protocol that is used by the chip to provide the GPS infos is MEIF. The GPSD component is in charge of translating that to standard NMEA that is sent to the lib via the /dev/socket/gps Unix socket, created by GPSD. 

 h2. Attempts 

 We have written code to read data from the correct serial interface: 

 It currently doesn't work: it fails to somehow boot the chip. Though, it works after starting gpsd once and stopping it. It must be doing some kind of magic code to start the chip. 

 h3. Related gps.xml parameters  

 We have tried to change some parameters in gps.xml to see how it behaves: 

 |_. Parameter |_. Original |_. Changed to |_. Result | 
 | acPortName | /dev/s3c2410_serial1 | /dev/s3c2410_serial42 | The chip wasn't "booted" | 
 | gpioNStdbyPath | /sys/class/sec/gps/GPS_PWR_EN/value | /sys/class/sec/gps/GPS_PWR_EN/value2 | The chip was booted | 
 | gpioNResetPath | /sys/class/sec/gps/GPS_nRST/value | /sys/class/sec/gps/GPS_nRST/value2 | The chip was booted |