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 ;-)