TDCOFF value is changed?

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TDCOFF value is changed?

Contributor III


I changed TDCOFF value in FREEZE mode.

But TDCOFF value is changed whenever debug state is changed between suspend and resume.

- suspend : 01111

- resume : 11110

In this case, What is TDCOFF value?

please refer to as below.

1. suspend state

1) enter to FREEZE mode : FRZ - 1, HALT - 1

2.TDCOFF 변경_suspend상태.jpg

2) set TDCOFF value : 01111

2.TDCOFF 변경.jpg

3) exit FREEZE mode : FRZ - 01, HALT - 0

3.FREEZE MODE에서 나옴.jpg

2. resume state

1) TDCOFF value is kept as 01111 

4.TDCOFF 값이 변경되어있음_resume 상태.jpg

2) double click FDCTRL

5.레지스터 더블 클릭해서 녹색버튼 없앰_resume 상태.jpg

3) double click FDCTRL again : this register color is changed to green

6.레지스터 다시 더블 클릭_resume 상태.jpg

4) TDCOFF value is changed to 11110. why?

7.TDCOFF 값이 1 1110으로 바뀌어 있음_resume 상태.jpg

3.suspend state again

1) TDCOFF value is changed to 01111 again.

8.TDCOFF 값이 0 1111으로 바뀌어 있음_suspend 상태.jpg

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3 Replies

NXP TechSupport
NXP TechSupport

Hi Kim,

This is caused by P&E debugger (if you are using it, OpenSDA) which does not support real time register monitoring by default. If you click to “-not read-“ value, the “DEADBEEF” is displayed and bit fields represents part of this value. This is the reason the TDCOFF shows 0x1E.



You can try to install and test the “PEmicro’s GDB Server Plug-in for ARM devices” which allows to view variables and memory during code execution.

See more info in  

BR, Petr

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Contributor III

Hi. Petr.

Thank you for your answer.

I understood that TDCOFF value was set 01111 correctly

By the way, after terminating debug for the project set TDCOFF as 01111, when I restart debug, TDCOFF value was 00001 and TDCEN was 0.
How can I save this TDCOFF value?


1. TDCOFF is 01010 and TDCEN is 1


2. Terminate debug


3. after terminating debug, when I restart debug, TDCOFF is 00001 and TDCEN is 0


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NXP TechSupport
NXP TechSupport

Hi Kim,

The FDCTRL register's default value after reset is 0x80000100.

So if you do not configure this register within your code (in Freeze mode) the debugger will show default value.

BR, Petr

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