Title: LED Blinking on Custom nRF52840 Board but Not at Given Intervals

[Usha]

Body:

Hello,

I have designed a custom board using the nRF52840 and flashed a simple LED blinking code. The LED does blink, but not according to the specified time intervals in the code. Instead, it blinks at an unexpected rate.

Here are some details about my setup:

• Microcontroller: nRF52840
• SDK Version: [Specify your SDK version]
• Power Source: USB
• Firmware: A simple delay-based LED blinking code

Troubleshooting Steps I Have Tried:

1. Verified the GPIO pin configuration in the firmware.
2. Checked if the correct clock source is selected.
3. Measured the actual delay using a logic analyzer.
4. Confirmed that the LED circuit is correctly wired.

Despite these checks, the blinking does not follow the intended timing. Could this be related to the clock configuration or power settings? Any guidance on debugging this issue would be appreciated.

Thanks in advance!

[Jakob Ruhe]

Usha said:

The LED does blink, but not according to the specified time intervals in the code. Instead, it blinks at an unexpected rate.

It indeed sounds like the code assumes that the MCU has another clock configuration as input than what it actually has on your custom board. It is hard to guess without seeing the code or the schematic. You can read about clocks here: CLOCK - Clock control.

Perhaps test your blinking LED application also on a nRF52840-DK or similar to ensure that it works there as intended there.

[Usha]

we can connect external crystal to custom board ?

[Priyanka]

Hi Usha,

SDK Version: [Specify your SDK version]

Please specify the SDK version that you are using.

Usha said:

we can connect external crystal to custom board ?

Yes of course. You can use an external crystal as the clock source.

As Jakob mentioned in the previous comment, please go through the Clock control documentation. Also, please make sure you schematic is following the Nordic reference designs. 

Moreover, as mentioned in the previous comment, please try to run your firmware on a nRF52840DK and see if the issue persists. If so, then it should be a firmware issue, else it's a problem with the clock configuration.

-Priyanka

[Usha]

SDK version:2.5.1

[Priyanka]

Priyanka said:

Usha said:

we can connect external crystal to custom board ?

Yes of course. You can use an external crystal as the clock source.

As Jakob mentioned in the previous comment, please go through the Clock control documentation. Also, please make sure you schematic is following the Nordic reference designs. 

Moreover, as mentioned in the previous comment, please try to run your firmware on a nRF52840DK and see if the issue persists. If so, then it should be a firmware issue, else it's a problem with the clock configuration.