[En-Nut-Discussion] NutOS (trunk) causes freeze

Rob van Lieshout (PragmaLab) info at pragmalab.nl
Wed Jul 18 20:24:18 CEST 2012

Hello Uwe,

> LPC people should check why the DWT counter doesn't count. DWT and DWT->
> CYCCNT are optional features on CM3 chips, but for me the wording in
> UM10470 (LPC178x/7x User manual)
> - The Data Watchpoint and Trace (DWT) unit is included. The DWT allows
>   address or data value matches to be trace information or trigger other
>   events. The  DWT includes 4 comparators and counters for certain
>   events.
> sounds like DWT and DWT->CYCCNT are available on LPC.

The thing that comes closest is the SysTick timer that is present in the
LPC177x_8x MCU. But that one only contains one counter and resides on a
different address then your recent CORTEX modification contains:

0xE000E010 CTRL 
0xE000E014 LOAD (your CYCCNT)
0xE000E018 VAL
0xE000E01C CALIB

The addresses you use in your CORTEX modification (now: MCU_STM32
modification) are in a reserved area of the LPC MCU. Might explain the

Can you point me to the DWT description in the user manual? I have here the
UM10470 (LPC178x/7x) user manual and that one doesn't know about a Data
Watchpoint and Trace Unit (DWT)..... 

I know that
F.html describes this module as being a part of Cortex M3 but at the same
time they state that it is a _configurable_ option (just like trace cells,
MPU etc). Again, I can't find this module in our LPC.... but I might
overlook something? 



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