LSERDY is asserted even if oscillator is not connected
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‎2019-08-01 07:26 AM
I am using stm32F746. I have enabled the RTC via external oscillator using CubeMX.
The crystal is not connected. But I see that RTC is initialized without errors (no timeout) and LSERDY is 1. Manual says LSERDY is 1 when external oscillator is running.
How that could be possible?
- Labels:
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RCC
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RTC
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STM32F7 Series
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‎2019-08-01 09:02 AM
Is the oscillator input pin of floating? It may pick up noise.
The LSERDY circuit is a counter, there's no discrimination for the frequency.
JW
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‎2019-08-01 09:07 AM
That's kind of weird, a custom design? Things hung of PC13..15 ?
Up vote any posts that you find helpful, it shows what's working..
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‎2019-08-01 09:09 AM
Thanks for reply. They are floating. I will try to ground them and check.
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‎2019-08-01 11:36 AM
Better disable RCC_BCDR_LSEON and keep the LSE pins floating.
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‎2019-08-11 09:48 AM
Hi all
I have checked that if both pins of oscillator are connected to the ground LSERDY is still set. A bit strange.
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‎2019-08-11 11:17 PM
That indeed is.
Can you please output LSE to MCO1 and check if there are no oscillations?
You don't set LSEBYP, do you?
JW
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