System architecture

The system architecture is easy; the micro controller will implement a micro http server accessible from a local area network through an Ethernet controller. If the local area network is accessible from internet even better, although in such case, some security issues may arise. The http request will trigger a temperature measure event; a specific message is published to the One wire bus and catch by all sensor which star individually to perform and A/D conversion during approximately 750 msec, after this period, the microcontroller address every sensor in order to retrieve the measured temperature, a web page is constructed with the information obtained and sent back as http response. The response time is about 1 second, not too match for a timeout. In order to get the http response independent from the A/D conversion time both (httprequest/response and temperature measure) should be implemented in separate threads, but a multithreading application may be difficult to implement in an 8bit microcontroller of just 8KB, I’ve seen some micro mini OS for AVR microcontrollers like FEMTOOS or PYXIS-OS which may solve the multithreading problem.

System architecture