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Multiple JTAG Targets?

Question asked by nate.domin on May 21, 2014
Latest reply on May 21, 2014 by PatrickN

I'm confused by the JTAG output scans of an EVAL-ADUC7023QSPZ1 board. -- According to the schematic, the U5 (FT2232HL) is disconnected from the JTAG lines.  But when inspecting the JLink.exe output I see 2 JTAG devices:


PS C:\Program Files (x86)\SEGGER\JLinkARM_V484e> .\JLink.exe -Device ADUC7023

SEGGER J-Link Commander V4.84e ('?' for help)

Compiled Apr 28 2014 20:50:11

Info: Device "ADUC7023" selected (62 KB flash, 8 KB RAM).

DLL version V4.84e, compiled Apr 28 2014 20:50:02

Firmware: J-Link ARM V8 compiled Nov 25 2013 19:20:08

Hardware: V8.00



Feature(s): RDI, GDB

VTarget = 3.287V

Info: ADI system TAP: Connecting to device with system TAP.

Info: TotalIRLen = 5, IRPrint = 0x11

Info: Analog devices system TAP: Enabling CPU core.

Info: TotalIRLen = 9, IRPrint = 0x0011

Found 2 JTAG devices, Total IRLen = 9:

#0 Id: 0x4F1F0F0F, IRLen: 04, IRPrint: 0x1, ARM7TDMI-S Core

#1 Id: 0x028011CB, IRLen: 05, IRPrint: 0x1, System level TAP

Found ARM with core Id 0x4F1F0F0F (ARM7)

RTCK reaction time is approx. 504ns

Using adaptive clocking instead of fixed JTAG speed.


What is the second JTAG device?   A preliminary inspection of R35, R36, R37, R38 shows that they are not populated (by design).