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PSoC™ 5, 3 & 1

KeLa_4479261
New Contributor II

Greetings to All:

I am trying to reduce the ppm number on the 5LP.  I have enabled the USB tab in the clock settings and have got a clock running at 1250ppm.  I was hoping to attach an external crystal with some capacitors and use them to create a more accurate clock.

I was hoping to use a watch crystal with 20ppm.  This is desirable as I am looking to microsecond timers that would be accurate.

Can I use the watch crystal, create and use a clock based off this at 24Mhz?

I am trying to locate documentation on this and my searches do not amount to any thing.

Help is appreciated, regards.

Ken.

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1 Solution
MotooTanaka
Esteemed Contributor

Hi,

I'm sorry hearing that the USB Clock of 5LP does not have enough accuracy.

I tried with CY8CKIT-059. (5LP)

I'm afraid that there is no path from XTAL 32kHz to Master Clock.

The XTAL needs to be 4MHz ~ 25MHz.

000-5LP-clocks.JPG

Then I tried with CY8CKIT-044 (4200M)

If I set wco (32kHz) with 20PPM accuracy

001-4200M-low.JPG

We can trim IMO with WCO, so that IMO accuracy is +/- 0.2%

002-4200M-High.JPG

moto

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