
UM10850
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2016. All rights reserved.
User manual
Rev. 2.4 — 13 September 2016
406 of 464
NXP Semiconductors
UM10850
Chapter 29: LPC5410x Serial Wire Debug (SWD)
The JTAG boundary pin functions are selected by hardware at reset. See
The following setup is required to enable SWO output on GPIO PIO0-15 (FUNC2) or
PIO1_1 (FUNC2):
1. Write 0x00000001 to TRACECLKDIV (0x400000E4). Enables the Trace divider.
2. If the clock to the IOCON block is not already enabled, write 0x00002000 to
AHBCLKCTRLSET[0] (0x400000C8). The clock must be enabled in order to access
any IOCON registers.
Table 457. JTAG boundary scan pin description
Function
Direction
Description
TCK
Input
JTAG Test Clock.
This pin is the clock for JTAG boundary scan when the RESET pin is LOW.
TMS
Input
JTAG Test Mode Select.
The TMS pin selects the next state in the TAP state machine. This pin
includes an internal pull-up and is used for JTAG boundary scan when the RESET pin is LOW.
TDI
Input
JTAG Test Data In.
This is the serial data input for the shift register. This pin includes an internal
pull-up and is used for JTAG boundary scan when the RESET pin is LOW.
TDO
Output
JTAG Test Data Output.
This is the serial data output from the shift register. Data is shifted out of
the device on the negative edge of the TCK signal. This pin is used for JTAG boundary scan when
the RESET pin is LOW.
TRST
Input
JTAG Test Reset.
The TRST pin can be used to reset the test logic within the debug logic. This pin
includes an internal pull-up and is used for JTAG boundary scan when the RESET pin is LOW.