The Global Positioning System (GPS) is a a satellite positioning system, using a constellation of 31 satellites.
GPS uses these as "man-made stars" to calculate positions to within a meter. With some forms of GPS. measurements accurate to better than a centimeter can be made.
With advancing technology, receivers have shrunk from several dozen ICs and hundreds of other components, to one, and a handfull.
This has drastically reduced costs.
The reducing cost has enabled it to be easily integrated in phones, laptops, cameras, as well as more traditional apparatus such as farming equipment, navigation systems and construction equipment.
(Another helpful overview Global Positioning System Overview)
is described on a page of its own.
The PMB 2520 Hammerhead is a one-chip solution for GPS that is produced by Infineon Technologies in cooperation with Global Locate. It allows the usage of assistance data by supporting A-GPS standards.
(all infomation is coming from the datasheet of PMB 2520) short datasheet
The Hammerhead consists of the following modules:
The Hammerhead integrates 3 serial interfaces:
The UART in the Hammerhead is a full-duplex UART interface. It is fixed in 8N1(8 data bits, no parity, 1 stop bit) mode. On the GTA01, the host processor connect with the Hammerhead through the UART. In all models of Neo1973, this is connected to a serial port.
The Hammerhead driver software will be delivered as a binary, which can be interfaced to gpsd as it outputs NMEA information, as many serial GPSs do.
The gps driver is now available. (There were some problems in the past getting a license to distribute the binary. [1])
The gpsd libraries provide the following infomation to the high level software:
The high level software sends the following messages to the plugin:
Gpsd communicates with the system at the following part:
At the GTA01, the host processor is a S3C2410.
On the GTA01, the Hammerhead are configured that connected with the host processor through the UART. The UART of data output/input is connected to the UART 1 of the SC2410. The UART of the hardware flow control is connected to the UART 2 of the SC2410.
To get gpsd working on the Neo Freerunner you have to run the following commands:
echo "GPS_DEV=\"/dev/ttySAC1\"" > /etc/default/gpsd /etc/init.d/gpsd restart
See also Server:A-GPS.
A:
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