The Design Of Embedded Iot System Based On PMB7900

With the integration and development of embedded technology and internet of things technology, smart home technology based on embedded technology improves continuously. However, the existing smart home technology is designed for the new type of smart appliances, lacking consideration for the upgrading of old appliances. Currently, the smart home system usually consists of a main controller and a separate wireless transceiver module, having the disadvantage of complexity in hardware and software design, high cost and high power consumption. So a simple, low cost, low power consumption and is compatible to the old appliances system needs to be designed.To meet those above requirements, an embedded IOT(Internet of Things) system based on PMB7900 is proposed. In this paper, we focus on designing an embedded networking module based on PMB7900, the main work is as follows:(1) The IOT module project design and hardware selection is discussed and analyzed, and the minimum system design is accomplished with the PMB7900 as the core chip. The minimum system includes PMB7900, power supply, SIM card, and circumscribed Flash and power amplifier(PA), etc.(2) The low-power design plan based on the dual core architecture is constructed, and the dual core architecture is formed by PMB7900 and MCU. The circuit design of communication between MCU and PMB 7900, external communication interface(I/O, IIC interface), power circuit and battery voltage acquisition, etc. is accomplished. After adopting the dual core architecture, the standby current at idle hours declines from 1mA-2mA to 30μA-140μA.(3) The external radio-frequency circuit of the IOT module is designed. At first, the radiating circuit and receiving circuit of GSM900 and DCS1800 frequency band are designed, and then calibration and test analysis are conducted by combining the main technical indexes of the radio-frequency circuit.(4) The software architecture design of IOT module is accomplished. Firstly, the receiving and dispatching of SMS package of Wipay application is designed and implemented with the ULC3 message mechanism, and then, with IOT water and gas meter as an example, the application of MCU is designed and implemented.Finally, the typical application introduction is carried out for the embedded IOT system. The working means and business flows of the back-stage management system are analyzed, and test demonstration is carried out for the IOT water and gas meter.