Development And Design Of Embedded Modem

The developing project of this thesis is an Embedded-Modem, which is used in data transmission of Tax-controlling POS machine developed by QingDao Hisense Intelligence Commerce Inc. The Tax-controlling POS machine is a project set up by the government. The company is the second to none in the development and application of the POS machine and has absolute advantage in the market.With the Modem development in home and abroad, and through careful market research and comparison, the Company decided to adopt ISOModem chip unit of Silicon Laboratories as top development chip to take the place of that of Rockwell. So that both are greatly improved the capability and the appearance size of the Embeded-Modem.The ISOModem of Silicon Laboratories integrates micro controller, DSP, encoder and DAA into very small-sized chip solution plan, whose circuit board area is one half less than and power consumption is only one third of that of the other plans. The high integration makes the design of Hisense's commercial Tax-controlling POS machine much easier.ISOmodem chip unit applies double-chip type: Modem controlling chip Si2457/34/15 and DAA chip Si3018. Modem controlling chip Si2457/34/15 is to control the Modem communication and provide the communication interface to the micro controller; DAA chip Si3018 is to modulate digital signals into analog signals, and then output them, or demodulate analog signals it receives into digital ones.This article detailedly introduces the working prototype, hardware organization cautions in design and debugging of the Modem. It also comprehensively discusses the interference immunity of the circuit. It raises solutions to the problems in Modem to help with the design of economical products with reliable capability.Electro Magnetic Compatibility (EMC) is a new field which is growing with the development of modern microelectronic technology, computer technology and control system technology; which is getting improvement during its adaptation to the development of microelectronic circuit chip. The development of electronictechnology brings along that of EMC technology. Currently a lot of techniques are introduced into China, which make our electronic technology into a new stage and which make our technicians aware of some new fields that they were never aware of. EMC is one of them and is very important area.This article detailedly depicts the factors that cause Electro Magnetic Interference and the components to restrain it. The anti-jamming technique in the design of PCB is also presented.