UM10413
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© NXP B.V. 2011. All rights reserved.
User manual
Rev. 1 — 16 December 2011
242 of 268
NXP Semiconductors
UM10413
MPT612 User manual
26.8.1 Enable debug mode
Debug mode is enabled using pins JTAGSEL and RTCK.
To enable Debug mode, JTAGSEL must be HIGH during and after the CPU is reset. Keep
JTAGSEL LOW at all times for normal (non-debug) operation; see
For debugging with JTAG pins, RTCK must be HIGH as the RST pin is released; see
. RTCK can be driven HIGH externally or allowed to float HIGH via its on-chip
pull-up. The RTCK output driver is disabled until the internal wake-up time has expired,
allowing an interval between the release of the external reset and the release of the
internal reset during which RTCK can be driven by an external signal if necessary.
This procedure establishes the PIO27 to PIO31 pins as the JTAG test/debug interface. Pin
connect block settings have no affect on PIO27 to PIO31 pins if they are initialized as
JTAG pins.
For the effect of hardware override related to JTAGSEL and RTCK, see
“MPT612 pin description” on page 58
.
(1) JTAGSEL is tied or pulled LOW at all times. An internal pull-down causes JTAGSEL to be LOW if it
is not pulled HIGH externally.
(2) RTCK is not connected in the application and is pulled up internally.
Fig 69. Waveforms for normal operation (not in Debug mode)
aaa-000631
RST
JTAGSEL
(1)
RTCK
(2)