OMAP-L137
SPRS563G – SEPTEMBER 2008 – REVISED JUNE 2014
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6.30.1 JTAG Port Description
The device target debug interface uses the five standard IEEE 1149.1(JTAG) signals (TRST, TCK, TMS,
TDI, and TDO), a return clock (RTCK) due to the clocking requirements of the ARM926EJ-S and EMU[0].
TRST holds the debug and boundary scan logic in reset (normal DSP operation) when pulled low (its
default state). Since TRST has an internal pull-down resistor, this ensures that at power up the device
functions in its normal (non-test) operation mode if TRST is not connected. Otherwise, TRST should be
driven inactive by the emulator or boundary scan controller. Boundary scan test cannot be performed
while the TRST pin is pulled low.
Table 6-114. JTAG Port Description
PIN
TYPE
NAME
DESCRIPTION
When asserted (active low) causes all test and debug logic in the device
TRST
I
Test Logic Reset
to be reset along with the IEEE 1149.1 interface
This is the test clock used to drive an IEEE 1149.1 TAP state machine
TCK
I
Test Clock
and logic. Depending on the emulator attached to , this is a free running
clock or a gated clock depending on RTCK monitoring.
Synchronized TCK. Depending on the emulator attached to, the JTAG
RTCK
O
Returned Test Clock
signals are clocked from RTCK or RTCK is monitored by the emulator to
gate TCK.
TMS
I
Test Mode Select
Directs the next state of the IEEE 1149.1 test access port state machine
TDI
I
Test Data Input
Scan data input to the device
TDO
O
Test Data Output
Scan data output of the device
EMU[0]
I/O
Emulation 0
Channel 0 t HSRTDX
6.30.2 Scan Chain Configuration Parameters
Table 6-115
shows the TAP configuration details required to configure the router/emulator for this device.
Table 6-115. JTAG Port Description
Router Port ID
Default TAP
TAP Name
Tap IR Length
17
No
C674x
38
18
No
ARM926
4
19
No
ETB
4
The router is ICEpick revision C and has a 6-bit IR length.
6.30.3 Initial Scan Chain Configuration
The first level of debug interface that sees the scan controller is the TAP router module. The debugger
can configure the TAP router for serially linking up to 16 TAP controllers or individually scanning one of
the TAP controllers without disrupting the IR state of the other TAPs.
6.30.3.1 Adding TAPS to the Scan Chain
The TAP router must be programmed to add additional TAPs to the scan chain. The following JTAG scans
must be completed to add the ARM926EJ-S to the scan chain.
A Power-On Reset (POR) or the JTAG Test-Logic Reset state configures the TAP router to contain only
the router’s TAP.
206
Peripheral Information and Electrical Specifications
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