CC2340R5: The external 32kHz crystal oscillator of the CC2340 sometimes fails to start properly.

wangrenli

Part Number: CC2340R5

Hi,

When the CC2340 is powered on multiple times, it has been found that the external 32.768kHz crystal oscillator sometimes fails to start oscillating. During debugging, it was discovered that the program does not enter the PowerCC23X0_oscillatorISR interrupt. What could possibly cause this issue? The crystal oscillator is connected to an external 15pF capacitor.

Normally, after a successful start of the 32.768kHz crystal oscillator, the code would enter this section, but when the issue occurs, it does not enter here.

sdk:simplelink_lowpower_f3_sdk_7_40_00_64、basic_ble_oad_onchip

30 days ago

0 Jake Pulliam 30 days ago

TI__Expert 4660 points

Hello,

Please make sure the crystal meets the following requirements:

Is this repeatable on multiple devices? With your code is it repeatable on the TI reference design (LaunchPad)?

It could be a layout issue. You can submit a schematic and layout review request at https://www.ti.com/tool/SIMPLELINK-2-4GHZ-DESIGN-REVIEWS

BR,

Jake

0 wangrenli 29 days ago in reply to Jake Pulliam

Intellectual 500 points

Hi,

The issue can be reproduced on multiple devices, but my code is not replicable on the TI reference design (LaunchPad). The information I provided earlier was incorrect, and currently, there are no external capacitors connected.

+1 Jake Pulliam 25 days ago in reply to wangrenli

TI__Expert 4660 points

Hello,

Please make sure the proper load capacitance is placed. Without the correct load capacitance the crystal oscillator won't work correctly. Please place the proper load caps and report if the issue is corrected.

BR,

Jake

0 wangrenli 20 days ago in reply to Jake Pulliam

Intellectual 500 points

Hi,

With a 15p capacitor connected externally, it still has the problem of intermittent non-oscillation.

0 Jake Pulliam 18 days ago in reply to wangrenli

TI__Expert 4660 points

Please submit a design review request: https://www.ti.com/tool/SIMPLELINK-2-4GHZ-DESIGN-REVIEWS I still suspect an issue with the value for the load capacitance.

0 wangrenli 12 days ago in reply to Jake Pulliam

Intellectual 500 points

Hi，

DIO3 and DIO4 multiplex external 32k pins, these two pins I currently do not configure its mode, that is, use the default GPIO_CFG_NO_DIR, is this correct.

0 Jake Pulliam 12 days ago in reply to wangrenli

TI__Expert 4660 points

Yes, that matches the reset value for the IOC register which is correct.

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CC2340R5: The external 32kHz crystal oscillator of the CC2340 sometimes fails to start properly.