nRF5340 external clock requirement

[luker]

Hello,

This is probably a dumb question but, I'm having issues with an initial prototype for a product that has been given. The hardware engineer (me) designed and got a bunch of boards made for testing and forgot to add the 32MHz clock to the board (and traces to it) I've tried to find information regarding the clock for the micros and there is reference to internal clocks but I'm unable to find out whether the external clock is required to generate these or if its possible to enable the 32mhz clock internally.

Any support would be muchly appreciated. the next revision will have the clock on it but am hoping I can do some testing instead of just spending a bunch of money on paperweights.

[Einar Thorsrud]

Hi,

The 32 MHz crystal is needed for anything that requiers a precise clock, for instance the radio. But the MCU starts up using the internal HFINT clock, and the CPU runs of that. So as long as you don't use the radio or try to start the HFXO in any other way, you will be able to use the CPU etc, so you can do some basic testing.

PS: I suggest opening a new support case here to get your schematics and layout reviewed.

[luker]

Thank you, glad to hear I can at least get some testing done. I shall create a ticket to get this board and some changes I have already done reviewed for the next revision.

Side note, I was hoping this would explain the issues I'm having with this board but I fear there is more I don't understand regarding project/ board setup to get it to function correctly.

The board does appear to be programmed successfully, just nothing appears to be executing. Currently attempting to just get it to toggle an LED with no success.

[luker]

Just a note to this, If I flash the custom board using the nRF5340dk board set as the destination and toggle one of the leds on the custom board it does work. Using the custom build board files it fails to flash the LED, I've been looking into the boot side of things as I don't believe the application is getting to that point of running

[Einar Thorsrud]

Hi,

Is what you are saying that if you build for nrf5340dk_nrf5340_cpuapp and flash your custom board your simple app or blinky works? But with your own board files it does not?

Have you debugged and observed the log output? What does that tell you? Also, what is thed difference between your board files and the DK board files?

PS: There is a module on custom board files in the nRF Connect SDK Intermediate course: Lesson 3 – Adding custom board support.

[luker]

Hi Einar,

Thank you for your help. I didn't realise there had been another course released regarding nRF Connect, I went through it and used the example they provided to copy the DK files and change rename parameters accordingly and have now managed to get the board working.

[Einar Thorsrud]

Hi,

I am glad to hear you got it working. Thanks for letting me know.