Problem with writing certain SCU registers

[torbjoerntvermo]

Using a LPC4357 I am trying to configure P9_3 to have MCOA0 function.
If I write to the configuration register 0x40086000+0x49C it seems to have no effect I read back all zeros, but if I do the same for another pin (0x40086494) the change takes effect and I read back the correct value.
What can cause this behavior?

[kerryzhou · Accepted solution]

Hi Customer,

    Thank you very much for your detail information.

     I think your problem is caused by the LPC4357 user manual error.

    I check it again, I have found the address for SFSP9_3 is 0x40086000+0X48C, not like the document mentioned 0X49C, actually 0X49C is reserved:

   I have do the testing on my MCB1758 with LPCXpresso IDE, the debug interface also shows the address for P9_3 is 0x4008648c.

    So, please change the P9_3 address to 0x4008648c.

   I will report this document to our according department immediately, the problem will be fixed in the next doc reversion.

   Thanks a lot for your good question and sorry for the inconvenience we bring you.

Have a great day,
Kerry

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[torbjoerntvermo]

Hi Kerry,

Thanks for fast response to my question, I will test with the correct register address ASAP

Sincerely,

Torbjørn

[kerryzhou]

Hi Customer,

     Thank you for your interest in NXP LPC product, I would like to provide service for you!

    Please check your LPC4357 part number at first, TFBGA100 and LQFP144 package don't have P9_3, so please make sure your chip have p9_3.

  

0x40086494 is P9_5, LQFP144 have this pin, so please check your package, are you using LQFP144?

Wish it helps you!

If you still have question, please contact me!

Have a great day,

Kerry

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Note: If this post answers your question, please click the Correct Answer button. Thank you!
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[torbjoerntvermo]

Hi Kerry,

I am using a LBGA256 package and have a PCB where the signal is routed and I can measure the output.

What could cause the strange behavior that I can write to register 0x40086494 but not to 0x4008649C ?

Sincerely,

Torbjørn