Principle and Program Design of SI-PROG Programmer

The principle of SI-PROG programmer is introduced,the purpose is using UART chip in PC′s serial port to realize the ISP download of single chip computer.The level of SOUT,DTR,RTSandCTS pins of the 8250 chip in PC′s serial port could be controlled or read separately through a few internal registers of 8250,so the ISP programming of single chip computer could be realized by making use of those four pins.In this paper,both the logical relationship and the level translation of communication signals between 8250 and single chip computer are introduced,the characteristics of the receiver′s threshold voltage are analyzed and the condition of using the SI-PROG programmer is provided.In the end,the AVR single chip computer is taken as an example to introduce the downloading program design.The result indicates that using UART chip in PC′s serial port can realize the ISP download of single chip computer.The hardware circuit and software design are both simple.