Atmel AVR - Debugging Interfaces - JTAG


JTAG provides access to on-chip debugging functionality while the chip is running in the target system. JTAG allows accessing internal memory and registers, setting breakpoints on code, and single-stepping execution to observe system behaviour.

Atmel provides a series of JTAG adapters for the AVR:

  1. The JTAGICE 3 is the latest member of the JTAGICE family (JTAGICE mkIII). It supports JTAG, aWire, SPI, and PDI interfaces.
  2. The JTAGICE mkII replaces the JTAGICE, and is similarly priced. The JTAGICE mkII interfaces to the PC via USB, and supports both JTAG and the newer debugWIRE interface. Numerous 3rd-party clones of the Atmel JTAGICE mkII device started shipping after Atmel released the communication protocol.
  1. The AVR Dragon is a low-cost (approximately $50) substitute for the JTAGICE mkII for certain target parts. The AVR Dragon provides in-system serial programming, high-voltage serial programming and parallel programming, as well as JTAG or debugWIRE emulation for parts with 32 KB of program memory or less. ATMEL changed the debugging feature of AVR Dragon with the latest firmware of AVR Studio 4 - AVR Studio 5 and now it supports devices over 32 KB of program memory.
  2. The JTAGICE adapter interfaces to the PC via a standard serial port. The JTAGICE has been End-Of-Lifed, though it is still supported in AVR Studio and other tools.

JTAG can also be used to perform a Boundary Scan test, which tests the electrical connections between AVRs and other Boundary Scan capable chips in a system. Boundary scan is well-suited for a production line; the hobbyist is probably better off testing with a multimeter or oscilloscope.

Read more about this topic:  Atmel AVR, Debugging Interfaces

Other articles related to "jtag":

Wiggler (JTAG) - Serial Wire Debug
... Serial Wire Debug (SWD) is a 2-pin electrical alternative JTAG interface that has the same JTAG protocol on top ... On JTAG devices with SWD capability, the TMS and TCK are used as SWDIO and SWCLK signals, providing for dual-mode programmers ...
Wiggler (JTAG)
... Joint Test Action Group (JTAG) is the common name for the IEEE 1149.1 Standard Test Access Port and Boundary-Scan Architecture ... Today JTAG is also widely used for IC debug ports ... processor market, essentially all modern processors implement JTAG when they have enough pins ...
Segger Microcontroller Systems
... Segger also develops a JTAG emulator for ARM7, ARM9, ARM11, ARM Cortex-M0 / M1 / M3 / M4, ARM Cortex-R4 cores ... the mIDASLink, Atmel as the SAM-ICE, Digi International as the Digi JTAG Link, and IAR Systems as the J-Link and the J-Link KS ... This is the only JTAG emulator that can add Segger's patented Flash breakpoint software to an RDI compliant debugger to enable the setting of multiple breakpoints in Flash while ...
Intellitech - Electronics Development
... For example, to test more JTAG-based circuits at a time, the company has patented a technique called "Concurrent JTAG" enabling simultaneous test of multiple targets over JTAG (IEE 1149.1) without ... To enable PCB self-test, the company has patented self-contained on-board JTAG BIST ...
Wiggler (JTAG) - Client Support - JTAG Connectors
... There are no official standards for JTAG adapter physical connectors ... Production boards may omit the headers or when space is tight, just provide JTAG signal access using test points. 2×7 pin) used for MIPS based systems 2×5 pin Altera ByteBlaster-compatible JTAG extended by many vendors 2×5 pin AVR extends Altera JTAG with SRST (and in some cases TRST and an event ...