Do you have any idea what the JTAG is? To be honest, it’s a parallel port interface for either JTAG or BDM debugging. Well, it might be a little bit slower than a Raven, but it’s a much stable and easy to use device than Raven did.
Today’s project is all about the JTAG Debugger. For your information, this JTAG Debugger is based on an ATmega644 and it’s capable of controlling program execution by setting breakpoints and accessing registers and memory.
The ATmega644 is the big brother of ATmega164, but it has one USART less. By the way, the ATmega644 has the following features, included:
- 64-Kbyte self programming Flash Program Memory
- 4-Kbyte SRAM
- 8 Channel 10-bit A/D converter
- JTAG interface for on-chip debug
Different from the other project, this JTAG Debugger used two ATmega644 MCUs. You will program one of the microcontrollers with any arbitrary code, while the other microcontroller (the debugger) contains the actual debugging firmware. Since it has two microcontrollers, hence you’re able to interface with the debugger through a command window on HyperTerminal.
Since the ATmega644 consist an On-Chip Debugger unit, it can executes AVR instructions and set breakpoints without any hassle!