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PSoC™ 5, 3 & 1

Yash_r
New Contributor II

Hello everyone,

I have been trying to get a hang of the way to interface an RTC module (Waveshare PCF 8563) with PSoC 5LP.
And as a first step, I loaded up the RtcDesign01 firmware example that is provided with the PSOC creator 4.4 and programmed the device with some initial date and time values -> the LCD displays the  programmed values properly.

But then, there is no updation of the date or time values on the LCD and it just shows the same screen (with initial values - no changes) and I am unable to figure out the issue.

Can anyone please help to understand what could be going wrong here?

PS: Attaching the project in the Minimal Archive setting. If it doesn't open up, please import the RtcDesign firmware example provided in the PSOC creator.

Regards,
Yash

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1 Solution
MotooTanaka
Esteemed Contributor

Dear Yash-san,

As I am not a hardware engineer, I am not confident if we can provide external signal directly to the 32kHz Crystal Osc. For high frequency clock, many devices have direct input pin, but I don't think 5LP is providing a direct input for 32kHz.

Seeing the block diagram in the datasheet, Pin P15[3] should be the input pin,

but I don't know the required/acceptable electrical characteristic of this pin.

Since the Oscillator is designed to work with very little power consumption,

I would imagine that providing large current or high voltage could damage the device.

002-32kHz_osc.JPG

So, for the time being, I would not recommend you to directly provide a clock signal into this pin. 

 

Best Regards,

6-Aug-2021

Motoo Tanaka

P.S.I found the following table in the datasheet, max operating current is 1.0 uA.

003-kHzECO.JPG

View solution in original post

11 Replies
Yash_r
New Contributor II

Hello @MotooTanaka san,

Attaching the snapshot of the LCD.

As mentioned above, there's no change in the characters display -- RTC not working as expected.

Yash_r_0-1628230742308.jpeg
PS: I addressed the post to @MotooTanaka san since i didn't receive any response on the thread since yesterday.

Hope to hear from you soon.


Regards,
Yash

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MotooTanaka
Esteemed Contributor

Hi,

First the good news is, yes, I could download your project and opened it.

Second (possibly) the bad news is from the datasheet of RTC component,

I think that it requires a 32.768KHz crystal attached to the device.

Have you connected the crystal to the PSoC 5LP via P15[3], and P15[2]?

At least I could not locate the crystal from your picture.

moto

 

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Yash_r
New Contributor II

Hello Tanaka-san,

Thank you for pointing out the need to use an external crystal for the operation. Silly of me to have missed that part😅 (which is clearly mentioned in the doc).

Yash_r_0-1628236747708.png
Also, only connecting a 32.768KHz crystal would be okay, or is there a need to add some capacitors (22pF) like the one used in the waveshare board ?

Regards,
Yash

MotooTanaka
Esteemed Contributor

Dear Yash-san,

In the schematic of CY8CKIT-059

001-schematic.JPG

and if you take a look at the CY8CKIT-059 board, you can see C41 and C42 are already mounted 😉

 

So the last question is, why they decided not to load the crystal  (T^T) <- japanese crying face

 

Best Regards,

6-Aug-2021

Motoo Tanaka

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Yash_r
New Contributor II

Hello Tanaka-san,

Strange as to why the crystal was not added (maybe some internal reasons)😐!!!

Anyway, i will try connecting the crystal and then see if that's working properly or not and update by monday.

Thanks for your guidance.
Have a great weekend.

Regards,
Yash

MotooTanaka
Esteemed Contributor

Dear Yash-san,

After posting my last reply, I thought over the reason,

as the datasheet states, the accuracy of RTC is depending on the accuracy of the crystal, so may be they wanted to leave the chance to select the accuracy by the user.

(Beside the BOM cost, which might have been the biggest reason...)

Anyway, you, too, have a nice weekend!

Best Regards,

6-Aug-2021

Motoo Tanaka

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Yash_r
New Contributor II

Hi Tanaka-san,

I agree BOM cost would've been a major contributor, besides giving the customer the final decision.

BTW, what's your thought on using a Function Generator to generate the 32.768KHz frequency?
I know that the frequency can be generated, but what would you suggest the amplitude could be (maybe 5Vpp?), and what about square or sine wave?
And which pin the generated signal should be connected to P15[2] or P15[3]? Any need of connecting a resistor or something in series with the function generator output (before connecting to the PSOC pins)?

Regards,
Yash

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MotooTanaka
Esteemed Contributor

Dear Yash-san,

As I am not a hardware engineer, I am not confident if we can provide external signal directly to the 32kHz Crystal Osc. For high frequency clock, many devices have direct input pin, but I don't think 5LP is providing a direct input for 32kHz.

Seeing the block diagram in the datasheet, Pin P15[3] should be the input pin,

but I don't know the required/acceptable electrical characteristic of this pin.

Since the Oscillator is designed to work with very little power consumption,

I would imagine that providing large current or high voltage could damage the device.

002-32kHz_osc.JPG

So, for the time being, I would not recommend you to directly provide a clock signal into this pin. 

 

Best Regards,

6-Aug-2021

Motoo Tanaka

P.S.I found the following table in the datasheet, max operating current is 1.0 uA.

003-kHzECO.JPG

Yash_r
New Contributor II

Hello Tanaka-san,

 

I had the Waveshare PCF8563 RTC module, which had a 32.768KHz onboard.
So, I supplied the VCC and GND and just hooked up two wires from the crystal to the P15[2] and P15[3] pins on PSOC, and now the RTC component works properly.

Btw, is it possible to make the display the current system time and date on the LCD by some method? Or is it not possible because of the RTC comp being software?

 

Regards,
Yash

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MotooTanaka
Esteemed Contributor

Dear Yash-san,

I'm glad hearing that the RTC is now working properly.

> Btw, is it possible to make the display the current system time and date on the LCD by some > method? Or is it not possible because of the RTC comp being software?

I wonder if the following discussion can be some hint.

https://community.cypress.com/t5/PSoC-5-3-1-MCU/PSoC-5LP-RTC-UART-output/m-p/34826

Best Regards,

6-Aug-2021

Motoo Tanaka

P.S. I'm sorry but I must go now 😉

 

Yash_r
New Contributor II

Tanaka-san,

Thanks a lot for all the help. 
I will take a look at the thread and will create a new thread if I face some issues.

Thanks and Regards,
Yash