VAR-320SBC Reference Guide
Copyright © 2008 Variscite
4.6. JTAG Port
JTAG provides a way of driving and sampling the external pins of the device regardless of the
core state, as well as a mechanism for device debug. JTAG logic includes a test-access port
(TAP) controller, TAP pins, an instruction register, and Test Data registers (TDRs). The JTAG
interface is controlled through five dedicated TAP pins that interface to the TAP controller: TDI,
TMS, TCK, nTRST, and TDO.
Signal
Pin number Type
Description
NTRST P2-128
I
JTAG
Test
Reset
TDI
P2-130
I
JTAG Serial data input
TMS P2-132 I JTAG
Test Mode Select
TDO
P2-136
O
JTAG Serial data output
TCK P2-138 I JTAG
Test
Clock
19