[SOLVED - FAULTY HARDWARE] RTC not work

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pokemon99
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[SOLVED - FAULTY HARDWARE] RTC not work

Post by pokemon99 » Fri Aug 04, 2017 4:23 pm

Good afternoon. They sent a blue board without quartz 32.768. I tried to put a quartz from an old motherboard, but the RTC clock does not work. Tell me what could be the problem.

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ahull
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Re: RTC not work

Post by ahull » Fri Aug 04, 2017 4:24 pm

Do you have a picture of the board?
Are the crystal load capacitors fitted?
- Andy Hull -

pokemon99
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Re: RTC not work

Post by pokemon99 » Fri Aug 04, 2017 4:34 pm

Yes there is. Bottom of the board. Blue pill board

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ahull
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Re: RTC not work

Post by ahull » Fri Aug 04, 2017 5:17 pm

pokemon99 wrote:
Fri Aug 04, 2017 4:34 pm
Yes there is. Bottom of the board. Blue pill board
Do you have any way of measuring the load capacitors, since it is rather odd that the crystal is missing, so there is a chance that there are other issues with the board. Can you post a couple of pictures of your board, as modified with your crystal, both the front and back.
- Andy Hull -

pokemon99
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Re: RTC not work

Post by pokemon99 » Fri Aug 04, 2017 5:30 pm

Now there is no way. But I read that there should be quartz with an internal capacitance of 6pf
and the quartz of the motherboard has a capacity of 12pf

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ahull
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Re: RTC not work

Post by ahull » Sat Aug 05, 2017 7:59 am

You might also like to read through this thread -> http://www.stm32duino.com/viewtopic.php?f=15&t=132

.. and this one -> http://www.stm32duino.com/viewtopic.php?t=594

.. one other thing to consider, these small crystals are pretty delicate easily damaged when soldering, so it may not have survived the "transplant operation".

They are extremely cheap however, and you can easily pick up a replacement for a few cents for example -> https://www.ebay.co.uk/sch/sis.html?_nk ... 2749.l2658

If you have access to an oscilloscope, you can check to see if the oscillator is oscillating, by scoping the pins of the RTC crystal.

If you don't have an oscilloscope then you might enjoy these links.
http://www.stm32duino.com/viewtopic.php?t=107
https://github.com/pingumacpenguin/STM32-O-Scope/wiki

One other trick, try placing your finger on top of each of the load capacitors in turn and see if the oscillator starts. The small change in capacitance and a little bit of interference induced by your finger may be enough to start it.
- Andy Hull -

pokemon99
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Re: RTC not work

Post by pokemon99 » Sun Aug 06, 2017 12:03 pm

Ok. For my project the exact time is not so important, I need a clock timer. I can use the internal crystal 40khz, I understand that time will be in a hurry. How will it be calibrated before 1 minute?

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RogerClark
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Re: RTC not work

Post by RogerClark » Sun Aug 06, 2017 12:16 pm

I would check the manual for the STM32F103C8T, to see if 40Khz is supported as a RTC crystal

I know on some MCU's they are tuned to only work with a 32kHz crystal and you can't use any other values, because the oscillator circuit inside the MCU will not run.

pokemon99
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Re: RTC not work

Post by pokemon99 » Sun Aug 06, 2017 4:27 pm

On another forum I read what works, but hours per day rush for 6 minutes. I did not exactly check, but I did a sketch with blink, it works. I'll find out more precisely tomorrow.

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RogerClark
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Re: RTC not work

Post by RogerClark » Sun Aug 06, 2017 10:23 pm

Ok..

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