Abstract: A T5557 RF card system based on microcontroller MSP430 is developed. In order to achieve low cost, low power consumption and high reliability requirements of instrumentation applications, this paper uses microcontroller on-chip peripherals to generate 125kHz signal, which is amplified by power and modulation to provide power and data for RF card; While taking advantage of the on-chip timer measuring RF card returns signal pulse width to decoder card to return data and achieve RF card read/write function. By applying this design in the prepaid calorimeter, the system successfully achieves such as data exchange recharge and maintenance etc functions; by experiment, it fully meets the requirements of performance, cost and power of instrumentation system.

Key words: RF card, T5557, MSP430