The development tools available for tracking device

The development tools available for GPS application design vary depending on the complexity of the target system and the GPS solution being used. Most GPS tracker vendors offer software tool suites that allow a developer to communicate with the GPS receiver through the serial port of a personal computer. These software tools typically use messages compatible with the standard NMEA (National Marine Electronic Association) format, but many vendors also offer their own customized sets of messages and message formats. 

The more advanced development tools, available for some GPS chip sets, are intended to help the application developer integrate their software with the GPS tracking software running on the same MCU. Because of the hard real-time constraints typical of GPS software implementations, the most efficient way to enable the smooth integration of the GPS tracking platform with the application software is through a clearly defined software API. With a standard interface to the GPS software and the necessary development/debugger tools to support it, an application developer can easily configure the GPS receiver software, enabling access to the appropriate PVT information by the application as needed. For an illustration of the basic software architecture of a GPS enabled application running on a single MCU that is supported by this type of tool suite.

For those developers that have the skill of designing the entire GPS receiver circuit into their application, several semiconductor manufacturers now offer GPS chip set solutions. These chip sets, offered with either complete or partial reference designs and control software, enable the designer to integrate GPS into an application at the lowest possible cost, while also conserving power, board space and system resources. However, this high level of integration is achieved at the expense of doing the RF and IF circuit layout and software integration in-house, which can take significant resources and effort. The custom chip sets used for the original GPS receivers often had up to seven ICs, including the external memory chips, amplifiers, downconverter, correlator ASIC and system processor, in addition to a variety of discrete components. Continuous advances in the performance and integration level of MCUs have greatly increased the performance of the newer GPS chip sets while reducing the power consumption and physical size of the complete system. System-on-a-Chip (SoC) technology has resulted in the integration of the GPS correlator directly onto the MCU, along with embedded RAM, ROM and FLASH memory. In some cases, this increased level of integration has reduced the device count down to a mere two ICs and a handful of discrete components, further decreasing the cost and development effort required. 

Even more recently, high-performance RISC MCUs have begun showing up in low-cost GPS chip set solutions. These powerful processors have many more MIPS available for GPS computations, which in turn increases the overall performance and reliability of the tracking device . This level of computational power is making it possible to execute dead reckoning or WAAS algorithms on the same processor as the GPS algorithms, further improving the accuracy of the positioning solution at little or no increase in chip set cost. This diagram illustrates all of the functional blocks required by a basic GPS system, including an active antenna, a downconverter with an integrated temperature sensor, and a correlator integrated onto a basic microcontroller, along with the additional MCU peripherals required to perform a basic tracking loop routine and calculate a PVT solution.