Applying 0 V to DEC2 causes freeze which cannot be returned using RESET pin.

RE: Applying 0 V to DEC2 causes freeze which cannot be returned using RESET pin.

Haruki Kawakami — Thu, 15 Mar 2018 06:20:59 GMT

Hi,

Thank you for describing. I understand I can recover from this is only by toggling power.

RE: Applying 0 V to DEC2 causes freeze which cannot be returned using RESET pin.

run_ar — Tue, 06 Mar 2018 13:37:14 GMT

Hi,

We only guarantee that the chip will not be damaged as long as the ESD is within the limits given above. Unfortunately we cannot control the state of the chip when this happens, so undefined behavior is expected. I am afraid the only way you can recover from this is by toggling power. I am sorry for the inconvenience. However, as said, it is not possible to predict the state of the chip after an ESD discharge.

RE: Applying 0 V to DEC2 causes freeze which cannot be returned using RESET pin.

Haruki Kawakami — Mon, 05 Mar 2018 13:05:39 GMT

This is an actual problem. We carried out ESD test to our product, then CPU hung up, and sending reset signal to RESET pin or sending reset command via SWD had no effect. We analyzed what caused this symptom, and found that dropping DEC2 to ground for a moment caused the same symptom, so we assumed static electricity made DEC2 connected to ground for a moment.

Anyway, how this symptom happens is not important.

It is important to know how we can reset the CPU when such like this symptom happens. As I wrote above, sending reset signal to RESET pin or sending reset command via SWD had no effect.

Do you have any idea?

RE: Applying 0 V to DEC2 causes freeze which cannot be returned using RESET pin.

run_ar — Mon, 05 Mar 2018 09:36:17 GMT

Hi again

That does not make sense. How does that happen? Please note that the chip is tested for ESD, In the datasheet you can see that the maximum values for a limited amount of time are:

ESD HBM

Human Body Model

ESD CDM_QF

Charged Device Model

(AQFN73, 7×7 mm package)

750

Exceeding this limits might damage the chip.

RE: Applying 0 V to DEC2 causes freeze which cannot be returned using RESET pin.

Haruki Kawakami — Mon, 05 Mar 2018 08:42:09 GMT

Hi,

Of course DEC2 is not connected to ground on our board, but sometimes static electricity connects DEC2 to ground.

RE: Applying 0 V to DEC2 causes freeze which cannot be returned using RESET pin.

run_ar — Mon, 05 Mar 2018 08:08:35 GMT

Hi,

Why do you connect dec2 to 0v? The product specification says this should not be connected see reference schematic.

Best regards,