oscillator initialization not completed

[martinodeluca]

Hello, I'm developing in a company a project on a SKEAZN64 and I have a problem with the external quartz. The problem is that sometimes (often) the oscillator (using FEE mode) does not complete the initialization so the debug is stuck on the line 

   while ((OSC_CR & OSC_CR_OSCINIT_MASK) == 0); /* Wait until oscillator is ready*/

Sometimes It happens that the process is completed. Why? is It a problem regarding capacitors or other? 

someone can help me?

thank u, bye

Martino

[kerryzhou]

Hi Martino De Luca,

   Normally, this problem is caused by the hardware.

  If your oscillator circuit design is not very good, it may cause the oscillating unstable problem.

  You need to find the proper load capacitor, please check your oscillator datasheet.

  Beside, the pcb layout is also very important. You can refer to the FRDM-KEA128 board:

http://www.nxp.com/assets/downloads/data/en/schematics/FRDM-KEAZ128-SCH.zip 

And this quick reference:

http://www.nxp.com/assets/documents/data/en/user-guides/KLQRUG.pdf?fsrch=1&sr=1&pageNum=1 

Page 19.

Have a great day,
Kerry

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

[martinodeluca]

Hello Kerry, thank you for the reply. I read the documents you linked me. Our design is slighly different from the one is mentioned in the pdf of the second link. Is it a possible cause of our problem. I want to show you our PCB in the part of the quartz connection and the MCU in order to valuate a possible errors. The quartz is a HC49 SMD 8 MHz and the capacitors are 12 pF. in the image below the quartz is the rectangle above OSC_X and OSC_Y and the capacitors are under it and above it. Thank you 

[kerryzhou]

Hi Martino De Luca,

   1. Please check your HC49 SMD 8 MHz from which company, and find the according datasheet, to check the load capacitor, choose the correct loader capacitor is very important.

    2. Please add 1M feedback resistor, just like the RM recommended.

Please add the feedback resistor at first, if still not OK, check the crystal datasheet, choose the correct load capacitor.

Have a great day,
Kerry

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