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)
The PMB 2520 Hammerhead is a IC sulution for GPS that producted by the Infineon Technologies. It allows the usage of assistance data by surpporting A-GPS standards.
(all infomations are getting 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 library. The library has two seperate interfaces for the software. One part of them provides an interface to communicate with the high level software. The other part is the HAL(Hardware Abstraction Layer), it is used to communicate with the system.
The library provides the following infomations to the high level software:
The high level software sends the following messages to the library:
The library communicates with the system at the following part:
At the GTA01, the host processor is a SC2410..
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.