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Testing the CC1310's 24Mhz and 32KHz crystal

Kummi
Mastermind 6220 points
Other Parts Discussed in Thread: CC1310

Hi,

How do we check if CC1310's external 24Mhz and 32khz crystal are running properly?
Our customer's board needs to be provided to the Crystal maker for the Crystal Macthing tests
in order to find out the oscillation allowance, oscillator stability etc of the crystals on the custom board.
(in case of MSP430 devices we used to get a complete Crystal Macthing report from the crystal maker)

Is CC13XXWARE's amplitude measurement is the only way to test the crystals?

Does the below "not to measure on the 24 MHz XTAL" condition apply also to CC1310?
processors.wiki.ti.com/.../CC26xx_Tips_and_Tricks

And can we assume both 24Mhz and 32khz will start oscillation after power-up without any
register settings in the software?

Best Regards
Kummi

  • 0
    TI__Guru**** 317180 points
    Q: Does the below "not to measure on the 24 MHz XTAL" condition apply also to CC1310?
    A: Yes

    Q: And can we assume both 24Mhz and 32khz will start oscillation after power-up without any
    register settings in the software?
    A: If the chip has never been flashed with any content the chip will use the internal RCOSCs. You have to run software that tell the chip to use the xtal.

    What is the criteria for testing the xtals? Do you just need something that tells you "Does this xtal osc run, yes/ no" or is more required?
  • 0 in reply to TER
    Mastermind 6220 points
    Hi TER,

    Thank you so much for the quick reply.

    Regarding the crystal oscillation after power-up, I asked this question
    because the below E2E mentions that.,
    "The board will start up on the internal oscillators and switch to crystal during boot time"
    ttps://e2e.ti.com/support/wireless_connectivity/bluetooth_low_energy/f/538/t/419947

    Regarding the criteria for testing the xtals, usually in case of MCU's
    our customers provide their prototype boards to the Crystal makers for the hardware tests
    like oscillator frequency vs load capacitance, Oscillation Allowance tests etc with the particular board
    and they will provide the test report whether the customer crystal circuit is optimized
    and the necessary parameters for the particular board.
    www.ndk.com/.../02_01.html
    But this could be done if there is a way to measure the crystal frequencies through a GPIO pin.

    Best Regards
    Kummi
  • 0 in reply to Kummi
    TI__Guru**** 317180 points
    In the BLE forum most customers run the BLE stack which switch in the xtals at boot. But as I wrote you have to have some software running on the chip to do the switching.

    It's not straight forward to output a signal to measure on.

    A couple of other options:
    - The RF frequency will be a function of the xtal frequency so it's possible to tune the xtal by checking the RF frequency.
    - Use a small antenna to "sniff" on the xtal. It is possible to measure the xtal without actually physically connect to it.