Strange problems when using AP6234(CYW43340) with STM32

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jawac_2707861
Level 1
Level 1

Here's my schematic. (Big photo see appendix)I try to use AP6234 module (CYW43340 solution) with STM32 in my project.

sch.PNG

But when I finish my layout and after manufacture, I met a strange problem:

When I use WICED SDK with snip.scan demo, the AP6234 only scans 2.4G APs.

And I tried to heat the board, and let the module maintain 100℃, now the scan result contains 5G APs.

But When the module cools down, it still only scans 2.4G APs.

I also tried the board called redbear duo:

https://github.com/redbear/Duo/blob/master/hardware/schematic/duo-schematic-v1.0.pdf

I moved the module to this board, the AP6234 works fine.

The strangest thing is my schematic is same as redbear-DUO board.

It's very strange, I don't know how to do. Who can help me?Thanks.

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jawac_2707861
Level 1
Level 1

I finally solved this problem.

This problem seems caused by the oscillator. The frequency of the 37.4MHz oscillator is not accurate enough. I changed one of the load capacitor of the oscillator ,and my circuit works fine now.

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