The WEBGIS Data Acquisition Design Based On FPGA

Based on the FPGA environmental data acquisition, the paper achieves the GPS positioning data acquisition, environmental information data acquisition and Wireless Network data transmission, which provides the basis environmental data for WEBGIS. For the hardware designing, a variety of interface circuits and power supply circuits were designed for the FPGA; for the software designing, the functions of modules were achieved by using VHDL, and verified by the simulation.The type of GPS positioning data is asynchronous serial ASCII code, including the time, longitude, latitude, altitude, satellite, speed and other information. Accordingly, using VHDL to design the string data conversion module to selectively receive and stored collected data in the RAM, waiting to be sent. Environmental information acquisition used DS18B20 digital temperature sensor, HIH-4000-003 humidity sensors, light resistance, gas-sensing resistor and ADC0809, to collect the temperature, humidity, light, gas concentration data respectively. The transmission part of wireless network was composed of two modules: AT commands sending module and string conversion module. The AT commands sending module was designed to send AT commands, whose data type is the parallel ASCII code .Through string conversion module the data was converted to asynchronous serial data, then, the converted data was sent to SIM300 data transmission devices, used to control data distribution.The type of GPS positioning data is asynchronous serial ASCII code, including the time, longitude, latitude, altitude, satellite, speed and other information. Accordingly, using VHDL to design the string data conversion module to selectively receive and stored collected data in the RAM, waiting to be sent. Environmental information acquisition used DS18B20 digital temperature sensor, HIH-4000-003 humidity sensors, light resistance, gas-sensing resistor and ADC0809, to collect the temperature, humidity, light, gas concentration data respectively. The transmission part of wireless network was composed of two modules: AT commands sending module and string conversion module. The AT commands sending module was designed to send AT commands, whose data type is the parallel ASCII code. Through string conversion module the data was converted to asynchronous serial data, then, the converted data was sent to SIM300 data transmission devices, used to control data distribution.