RTC (Real Time Clock) support

[Ishwar Sharma]

Hi,

We are looking to use nRF5340 device in our new design. We need RTC (Real Time clock) feature with this design.

Does nRF5340 device support RTC (Real Time Clock). nRF5340 supports only Real Time counters. 

Best Regards

Ishwar

[Kazi Afroza Sultana]

Hello Ishwar,

It may be possible. What do you intend to do implementing Real Time Clock in your design? A little bit details information is helpful.

Thanks.

Best Regards,

Kazi Afroza Sultana

[Ishwar Sharma]

Hi,

The RTC (Real Time clock) is needed for time and date.

Best regards

Ishwar

[Ishwar Sharma]

Hi,

Can you please update here.

Best regards

[Kazi Afroza Sultana]

Hello,

Sorry for late reply. Since we do not have any peripheral for Real Time Clock ((+) RTC real-time clock - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com)) so RTC is just a low power counter which cannot keep track of time during resets/power outages. 

If you are thinking of using an external device, can have a look at this driver (3231) specific API RTC — Zephyr Project Documentation (nordicsemi.com). You have to implement by yourself. 

There is a previous case (devzone.nordicsemi.com/.../using-nrf_connect-zephyr-with-the-comparator-interrupt) that may give you some relevant idea. There is no zephyr driver for that. So, you need to use nrfx driver instead (https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrfx/drivers/comp/driver.html). 

Hope it helps. Thanks.

Best Regards,

Kazi Afroza Sultana

[Ishwar Sharma]

Hi

Thanks for reply.

There is one more question here.

Do we need external pull up resistors on I2C signals (Data and Clock) with nRF52840 device?

Best regards

[Kazi Afroza Sultana]

Hello,

You can add external pull up resistor if you want. However, according to design, it is not necessary. All our pin has internal 13Kohm. This actually can restore the signal to high when no device is asserting it low.

BR

Kazi

[Ishwar Sharma]

Hi,

Thanks.

I have one more query as below.

What is the best way to configure unused GPIOs for minimum current consumption. This is our low power mode (Battery operated) application.

Please suggest configuration for unused GPIOs.

Best regards

[Ishwar Sharma]

Hi,

Can you please update here on priority.

Best regards

[Kazi Afroza Sultana]

Hello,

You can set the unused pins as input with disconnected buffers (as GPIOs are configured as inputs with the input buffer disconnected on reset), they will not draw excessive current due to floating.

https://infocenter.nordicsemi.com/topic/ps_nrf52840/gpio.html?cp=4_0_0_5_8_1_9#register.PIN_CNF-0-31.

Thanks.

Best Regards

Kazi

[Ishwar Sharma]

Hi,

Please see my below queries:

1. There are different option given for RF signal (ANT) connection with Antenna. What should be the matching circuit. Is there any calculation for this. We need to use SR4W035 Antenna (2.4 GHz) with NRF52840-QIAA-R device.

2. Do we need to populate series resistors and capacitors to Ground for I2C signals.

3. Should we go with High drive 0 and High drive 1 if the GPIO (output) is used with connector/Cable.

Best regards