How is JTAG used in debugging and programming?
JTAG is more than debugging and programming. You may be familiar with JTAG because you have used tools with a JTAG interface. Processors often use JTAG to provide access to their debug/emulation functions and all FPGAs and CPLDs use JTAG to provide access to their programming functions. JTAG is not JUST a technology for processor debug/emulation.
Why do FPGAs and CPLDs use JTAG technology?
Processors often use JTAG to provide access to their debug/emulation functions and all FPGAs and CPLDs use JTAG to provide access to their programming functions. JTAG is not JUST a technology for processor debug/emulation.
How does JTAG TAP state-machine, operate?
To understand how JTAG TAP state-machine, operates, we need to first look into some more details of a generalized TAP pseudo implementation. TAP controller contains an “Instruction Register (IR)” and one or more “Data Registers (DR)” that can be accessed over the 4-wire JTAG interface.
What are the characteristics of a JTAG interface?
Electrical characteristics. A JTAG interface is a special interface added to a chip. Depending on the version of JTAG, two, four, or five pins are added. The four and five pin interfaces are designed so that multiple chips on a board can have their JTAG lines daisy-chained together if specific conditions are met.
Why are JTAG interfaces important to electrical engineers?
The JTAG interface gives manufacturers a way to test the physical connections between pins on a chip. When electrical engineers talk about using JTAG to “debug” a chip, they are talking about something very different than traditional software debugging.
What was the original purpose of the JTAG?
JTAG is a common hardware interface that provides your computer with a way to communicate directly with the chips on a board. It was originally developed by a consortium, the Joint (European) Test Access Group, in the mid-80s to address the increasing difficulty of testing printed circuit boards (PCBs).