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PSoC™ 4 Forum Discussions

Anonymous
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I need to create a timeout that occurs 60 days after power up.  I realize that I cannot do this accurately but that is OK.  I would like to know the possible error.  The crystal I use (24 MHz) has a spec of 30ppm, the Creator IDE list the ILO tolerance of +-2%, which is correct?

Rich

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Anonymous
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Is the crystal different from the one built into the chip/module?

If it is an external crystal, then it is most likely that the +/- 2% is related to the accuracy of the Cypress hardware using the crystal, and the error will propagate through with that.

Otherwise, it could be the two errors are calculated together for the IDE, and each is showing the same number, but at different measurements (I think 30ppm is 0.003%, so probably not true).

Or, the specific selection of routing/signaling introduces some error into the circuitry, and is increasing the error from 0.003% up to 2% error.

Can you give a picture of where you are seeing the two numbers?

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Anonymous
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It is an external 24 MHz crystal.  30 PPM 30 PPM is from the crystal spec

+- 2% is listed in the Creater IDE cydwr clocks tab  Obviously the IDE does not "know" what the crystal accuracy is.

does the PSoC internal oscillator really add 2% error?

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ILO is the Internal Low-speed Oscillator. The ILO, and the IMO (internal main oscillator) are both RC-oscillators, and are trimmed to 2% accuracy. You can use an external _oscillator_  (not a crystal) as clock source - if you configure your project that way you can specify the accuracy of that oscillator.

Depending on the PSoC4 family you are using, you can also use the ECO (external crystal oscillator), then you can also configure its accuracy.

Maybe you can show the clock configuration dialog, so we can see what you have configured currently?

RyanZhao
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Hi Hendrik,

The accuracy of PSoC4 IMO can be +-2%.

However, the accuracy of PSoC4 ILO is -50%~+100% or +-60%(dependent on which PSoC4 series you use).

Kindly refer to details in datasheet.

Thanks,

Ryan

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RyanZhao
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Hi Rich,

Which device are you using?

Thanks,

Ryan

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Anonymous
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I am using the CY8C4127LQI-BL473

I have attached the clocks page

Thanks

Rich

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Anonymous
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And I should have said IMO not ILO...

Rich

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I actually wanted the page which shows which oscillators are active, and how the clock tree looks like (the one you get when double-clicking on the one you captured).

But I can already see that your system clock is derived from the IMO, not from the ECO. So you are not using the crystal (or an external oscillator). Configure your ECO properly, and then select it as source clock for HFCLK.

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