topic Re: PCA21125 RTC Get real time in Other NXP Products

PCA21125 RTC Get real time

AshBirari — Thu, 02 Nov 2023 12:44:35 GMT

Hello NXP,

I am trying to get the real time using RTC PCA21125.Following way I have implemented the RTC interface with AURIX TC389 controller using SPI communication.

Write Command : 0x10

Read Command : 0x90

SPI Configurations :

Data width : 8

Transfer Start : MSB

RTC Initialization :

Configuring Register Control 1 as 0x0C (POR_OVRD = 1, 12_24 = 1)[is this correct way ?]

Configuring Register Control 1 as 0x00

RF bit of SECOND regirster is always 1 as its default value.

trying to read the Second, Minute, Hour data from the register using SPI commands.

Observed Values :

Seconds : 0

Minutes : 19

Hours : 12

Re: PCA21125 RTC Get real time

TomasVaverka — Thu, 02 Nov 2023 12:38:40 GMT

Hello Ashwini,

I do not fully understand what is the issue you are facing.

I would recommend you to take a closer look at our UM10301, mainly chapters 12.1 - Initialization of the RTC and setting the time, and 6 - Oscillator.

The simplest way to check for oscillation is to use the CLKOUT pin. There should be a 32.768 kHz signal at pin CLKOUT available after power-on. If your design does not include a pull-up resistor to the CLKOUT, then add one temporarily.

BR, Tomas

Re: PCA21125 RTC Get real time

AshBirari — Thu, 02 Nov 2023 12:58:15 GMT

Thank you for suggesting me the UM10301 user manual. As given in the module, chapter 12.1 table 5 I need to initialize the RTC POR bit of Control register 1 and RF bit of Second register should be cleared. But I am facing issue while clearing POR bit of Control Register 1 and RF bit of Second Register. I am not able to clear these above bits. How can I resolve this issue ?