RTOS/CC2640: Unknown Reset when put scope probes on the output of PA

David Hsueh

Intellectual 520 points

Part Number: CC2640

Tool/software: TI-RTOS

I use 8 GPIOs of cc2640 to generate a AC signal,

and convert it to higher voltage signal by OP and PA.

When I put the scope probes on the output of PA(There is no load on PA output),

cc2640 will reset but I don't know why.

The Output Signal:

- ACV is about ±350~400V

- Frequency is about 100Hz.

FW: Based on SimpleBLEPeripheral(TI_RTOS:2.13.00.06)

MCU: cc2640

Why cc2640 reset? How to find the root cause and fix it?

over 8 years ago

0 A. Rebel over 8 years ago

TI__Genius 11740 points

Hi David,

Are you powering the OP and PA from the same source powering the CC2640? It's possible you could be causing a voltage sag large enough for brown out.

Regards,
Rebel

0 David Hsueh over 8 years ago in reply to A. Rebel

Intellectual 520 points

Hi Rebel,

Yes, the OP and PA are using the same power source as cc2640.

I have checked the VCC Pin by scope, but cc2640 doesn't reset.

So the reason of reset seems to be not the power source.

I find a strange situation like below:

Case 1

Audio Amplifier(PA) Output "+" ---------------- "+" Scope

Audio Amplifier(PA) Output "-" ---------------- "-" Scope >> cc2640 will NOT reset.

Case 2

Audio Amplifier(PA) Output "+" ---------------- "-" Scope

Audio Amplifier(PA) Output "-" ---------------- "+" Scope >> cc2640 will reset.

0 David Hsueh over 8 years ago in reply to David Hsueh

Intellectual 520 points

The output of PA is AC signal. (100Hz,±400V)
Is it possible that scope probe becomes as an antenna?
Is it possible cc2640 reset caused by radiation ?

0 JXS over 8 years ago in reply to David Hsueh

TI__Guru** 105180 points

Did you check the Reset Source register (AON_SYSCTL:RESETCTL.RESET_SRC)?

Best wishes

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RTOS/CC2640: Unknown Reset when put scope probes on the output of PA