Design And Implementation Of Agent Based Generic Cross-debugging Of Jtag Standard

Cross Debugging Agent,including debugging stub, debugging server, ROM Monitor and Rom Emulator, is an important component for the embedded cross debugging system. It is also the most widely-used method. Its biggest weakness is that the resources of target system and the time of processor are occupied. It influents the executing result of target procedures because of the difference between the ultimate target environment and the debugging environment. In Circuit Emulator can eliminate this effect by replacing the target processor, but a specific ICE is needed for each target processor and the price is high. Debugging technique based on On-Chip-Debugging makes up for the weakness, while it's not generic enough.Research of generic ICE based on OCD is still a front work. Although foreign generic ICE products are mature and stable, costs of them are still high. As the factors of fund and market, there have been very few domestic research on ICE.Based on the analysis of debugging agent, OCD technique and generic ICE products based on OCD technique, a generic debugging agent solution is proposed.It can make up for the shortage of debugging agent by separating the cross debugging agent from the target system using OCD technique. JTAG is selected as it is currently supported by the majority of embedded processor chips. By the solution, a generic debugging agent model is designed by using SOPC technology. The model is realized taking ARM7TDMI as the target processor.This generic debugging agent has the following basic functions: setting up breakpoints, single-step operation, continuous operation, reading and writing registers and memory, etc. Applying to different embedded processors, the only thing is to change the code relating to target processor in debugging agent. In the result, the debugging agent is capable to debug different kinds of target processors supporting JTAG.There are two important characteristics for this debugging agent. One is the independence. Influences are eliminated by separating the debugging agent from the target system. The other is the universality, which refers to that the model is generic and it can debug all the processors supporting JTAG.