NRF52 DK and BMD-300 - different low frequency clock speeds

RE: NRF52 DK and BMD-300 - different low frequency clock speeds

Hung Bui — Mon, 05 Dec 2016 08:25:08 GMT

You would need to calibrate manually, unless you are using the softdevice then it calibrate for you. I think you may also want to test the 16MHz clock, make sure it has proper frequency.

RE: NRF52 DK and BMD-300 - different low frequency clock speeds

AlekseyJ — Fri, 02 Dec 2016 22:26:54 GMT

BMD300 schematic with DC-DC converter. Try to enable DC/DC converter:

// Enable DC/DC converter
uint32_t err_code;
err_code = sd_power_dcdc_mode_set(NRF_POWER_DCDC_ENABLE);
APP_ERROR_CHECK(err_code);

RE: NRF52 DK and BMD-300 - different low frequency clock speeds

TenderLoins — Fri, 02 Dec 2016 15:46:16 GMT

It should automatically calibrate? I just tried downloading the SDK, and running the ble_app_uart example and it 'works' but constantly restarts. I think this module is faulty unless anyone has any other ideas?

RE: NRF52 DK and BMD-300 - different low frequency clock speeds

Hung Bui — Fri, 02 Dec 2016 15:06:59 GMT

Maybe you can try to calibrate the 32kHz RC as telling here? infocenter.nordicsemi.com/.../hardware_driver_clock.html

RE: NRF52 DK and BMD-300 - different low frequency clock speeds

TenderLoins — Fri, 02 Dec 2016 14:11:24 GMT

Both the NRF52 and BMD-300 are running for the internal RC 32kHz oscillator (they both use the custom_board.h config with the NRF_CLOCK_LFCLKSRC set to NRF_CLOCK_LF_SRC_RC).

I'll try the LED idea and see what happens.

The BMD-300 appears to be running faster than the NRF52, I'll get the exact difference and update this post.

I ran the output to my Saleae Logic, and toggled a pin inside the rtc_handler. The BMD-300 has a frequency of 17.32Hz while the NRF52 is 16Hz. It doesn't appear to have crashed.

EDIT: It has crashed now :(

RE: NRF52 DK and BMD-300 - different low frequency clock speeds

Hung Bui — Fri, 02 Dec 2016 14:09:03 GMT

Hi TenderLoins,

To avoid any delay may cause by other peripheral such as the UART, you can try to blink an LED instead of printing out something in the Tick.

In addition, you can try to test with only internal RC 32kHz not the external crystal. This can tell if it's the issue with the crystal or not.

Would the interval on the NRF52DK slower than it should or the Rigado board faster than it should ?