Design And Implementation Of ARM11 Debugging Software Based On JTAG

With more and more embedded intelligent products using ARM core processor as their development solution, the debugging method of embedded software based on ARM core processor has drawn more developers'attention. The new-designed ARM11 core processor from ARM company has been widely used in wireless devices, consumer products, automotive electronic control system and other fields. Therefore, based on JTAG technology to design and implement an ARM11 debugging system are helpful to debug low-level embedded software such as board supported packages, and it is also help developers to locate program bug fast.The hardware architecture of debugging system based on JTAG technology is divided into PC host, debug target and protocol converter. The PC host is used to run debugging system, while the debugged program runs on debug target. The PC host sends debugging command to JTAG interface of debug target through parallel port using protocol converter, meanwhile, it receives debugging information from JTAG interface by parallel port.The debugging system is divided into protocol layer and function layer by using a bottom-up designing method. The protocol layer consists of JTAG signal stimulation, state machine and boundary-scan chain modules. The JTAG signal stimulation module implements with read and write operations based on both Linux and Windows platform. The state machine module is achieved by using digital sequence method. Driven by JTAG signals, the state machine completes data transmission with state transition. The boundary-scan chain module accesses the instruction and data registers by using a rapid shifting method.Based on protocol layer, the function layer of debugging system is composed of function as reading and writing registers and memory, setting breakpoints and watchpoints. The function of read and write registers is implemented with debug communications channel provided by ARM11 core processor. Then, we introduce read and write memory as whole word, half word and byte unit based on interface of read and write registers. Finally, we set breakpoints and watchpoints through read and write breakpoints and watchpoints registers.