The Global Positioning System (GPS) is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations.
GPS uses these "man-made stars" as reference points to calculate positions accurate to a matter of meters. In fact, with advanced forms of GPS you can make measurements to better than a centimeter!
In a sense it's like giving every square meter on the planet a unique address.
GPS receivers have been miniaturized to just a few integrated circuits and so are becoming very economical. And that makes the technology accessible to virtually everyone.
These days GPS is finding its way into cars, boats, planes, construction equipment, movie making gear, farm machinery, even laptop computers.
Soon GPS will become almost as basic as the telephone. Indeed, at Trimble, we think it just may become a universal utility.
(from the GPS Tutorial)
(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.
The Hammerhead driver software is delivered as a binary, which can be interfaced to gpsd as it outputs NMEA information, as many serial GPSs do.
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.
A: Not directly. However, the gpsd program 'gpspipe', with the -r switch will output NMEA data with the current position information. The right way to do it is to use libgpsd in your program if possible.