SMAKN&reg; AVR USB JTAG Downloader Emulator Programmer Module AVR JTAG is a complete set of debugging tools based on chip JTAG interface that is compatible with Atmel company's AVR Studio, and support all AVR 8-bit RISC instruction with a JTAG port of the microprocessor. The JTAG interface is a 4-wire IEEE 1149.1 standard test access port (TAP) controller. The IEEE standards provide an effective board connectivity testing standard methods (boundary scan). Atmel's AVR device has been extended to fully support the programming and on-chip debug function. The AVR JTAG emulator used for emulates chip hardware, such as procedures for single-step, set breakpoints, etc. hardware emulation can understand the detailed operation of the chip inside the program. The AVR JTAG emulator is mainly used to simulate operation of the chip.