Week 11 - JTAG Flashcards
1
Q
What is JTAG?
A
- Joint Test Action Group
- Designed to Test and verify Printed Circuit Boards after manufacture using boundary scan
- Program on board Flash or EEPROM devices on a PCB.
- Uses a serial communication interface to probe the key components on a PCB in order to validate their correct operation. Achieved by inputing known data onto registers and testing the output against this expected data.
- Adopted by the Institute of Electronic Engineers IEEE 1149.1-1990 Standard
2
Q
JTAG Fault Detection
A
JTAG Fault Detection:
- Used to detect faults on Integrated Components of a PCB
- Isolate and identify common faults such as:
- Solder joints (open or short)
- Component misalignment, wire bond failure, track failure
- Connector failure
3
Q
The Test ACcess Port
A
- The connection interface used for JTAG is known as a Test
Access Port (TAP) on a PCB - Multiple connections used
- Identification and location can be a challenge
4
Q
JTAG Tools
A
- Low cost
- Designed for service needs - have read and write functions
- Combine SW/HW/Drivers/Cables/Jigs
- Support specific vendors/chipsets
- Other support many devices
- Developed from a non forensic
perspective - Various user interfaces/terminology
- Can appear/disappear from market quickly
- Level of support varies
- Lack of audit or hash addressed by work practice
- Tool mobile device support often quicker than commercial
tools - Large worldwide market driving innovation
- Bypass Operating system
- JTAG pinout support
- Additional acquisition support add-ons
- Missing battery or SIM may not prevent acquisition
- Slow download speed
5
Q
What are the 3 JTAG Connection Methods?
A
- Solder
- Jig (a term used for connecting to the device’s internal ports (e.g., JTAG, test points, micro-USB, or eMMC pins) via a specialized fixture, jig, or dongle that makes it easier to access the device’s memory, even if the phone is locked or damaged.
- Molex (a company that manufacturers various connectors / cables etc)
