nrf52832 external oscillator of 32MHz replace crystal

[wxgd]

I checked the nrf52832 manual and found that both XC1 and CX2 are analog input pins for the 32Mhz clock pin configuration. The reference design for both uses 32Mhz crystals for connection. Due to the excessive frequency deviation of the 32Mhz crystal, I connected the OUT pin of the 32Mhz active crystal oscillator to the XC1 pin, leaving the XC2 pin floating（The VCC and GND of the  oscillator have been correctly connected）. The actual test shows that it is effective and very stable. It works normally for several days. My question is whether a 32Mhz active crystal oscillator can actually be used. Thank you

[Asbjørn]

Hello,

Could you explain a bit more to what you are seeing as excessive frequency deviation, that does that mean and what are you seeing? 

You can have an active clock source connected as you've discovered. It's not the option we recommend, but it will work as long as the clock source is stable with regard to frequency and amplitude. It's not a feature we have documented or tested, so if you want to continue with a single pin clock input, it's at your own discretion.

Best regards

Asbjørn

[wxgd]

hi，

The frequency deviation of the crystal oscillator is too large. On my product, the phenomenon is that the scanning or connection to the slave device (both the master and slave devices are 52832) is extremely slow, or the connection drops immediately after connection, which is unstable. I guess it's caused by excessive frequency deviation of the crystal oscillator.

Thank you for your reply

[Turbo J]

That usually happens when you made a mistake calculating the loading capacitors on the crystal circuit. I believe nordic has an appnote or online calculator for these somewhere - compare the results with your schematic.

[PaKa]

Or you have a problem with the setting of the LF clock, are you using the correct settings for that as well?

[wxgd]

After I replaced the capacitance value of the capacitor, the problem of scanning the connection was solved

[wxgd]

no error with  LF clock setting