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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
612 of 808
NXP Semiconductors
UM10360
Chapter 33: LPC17xx JTAG, Serial Wire Debug, and Trace
Another issue is that debug mode changes the way in which reduced power modes are
handled by the Cortex-M3 CPU. This causes power modes at the device level to be
different from normal modes operation. These differences mean that power
measurements should not be made while debugging, the results will be higher than during
normal operation in an application.
During a debugging session, the System Tick Timer and the Repetitive Interrupt Timers
are automatically stopped whenever the CPU is stopped. Other peripherals are not
affected. If the Repetitive Interrupt Timer is configured such that its PCLK rate is lower
than the CPU clock rate, the RIT may not increment predictably during some debug
operations, such as single stepping.
Debugging is disabled if code read protection is enabled.