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external oscillators for i.MX8M

Question asked by Thomas Doerfler on Nov 22, 2018
Latest reply on Feb 14, 2019 by Benjamin Davis



for our i.MX8M HW design, we decided to use external 1.8V oscillators instead of mere crystals for the 25MHz and 27MHz clock generation. We applied them to pins XTALI_25M and XTALI_27M, which seems to be a problem: the processor does not come up on the JTAG debugging interface.


Some tests with the i.MX8M evaluation board reproduced the behaviour. When we attached the oscillator clocks to XTALO_25M and XTALO_27M though, the processor came up and booted fine.



- Can anybody give me a hint, how to understand this behaviour? 

- Is there a way to get the chip working without having to connect to XTALO_xxM pins? (due to layout restrictions, XTALO_25M and XTALO_27M not accessible on current hardware)

- Can we apply a resistor or capacitor divider or something like that?


Any hints warmly welcome ;-)