No problem on 2nd but malfunction on 3rd Rev chip

[Motti Ng]

We have been using SDKv11.0.0 with S130 softdevice on nRF51822-QFAA rev 2 on a custom board with no problems at all.

Since our nRF51822 BLE module vendor no longer support rev 2 chip, we need to change to rev 3.

It is found that new BLE module is NOT functioning properly.

The P0.11 pin (used as SPIM MOSI) is irregularly toggling by itself even if there is no SPI CLK.

Some of them are NOT even advertising.

With the same code on the rev 2 one, P0.11 pin is just pull high since there is no active SPI.

According to the compatibility matrix, rev 3 chip should support SDKv11.0.0 + S130.

Is there anything I am missing to migrate from rev 2 chip to rev 3 chip?

Do I need to modify the firmware to be run on rev 3 chip?

Thanks.

[Kenneth]

Hi,

Have you tried to swap chips (rev 2 and rev 3) between old and new module? Just to rule out other circuitry / components?

The rev 3 can directly replace rev 2, this is also described in the consequence of change on page 2 in the product change notice:
http://infocenter.nordicsemi.com/pdf/pcn_092_v1.2.1.pdf 

The only exception is that there are a very few new anomalies on rev 3 that you should check may apply:
http://infocenter.nordicsemi.com/pdf/nRF51822_pan_v3.3.pdf 

Best regards,
Kenneth

[Motti Ng]

Hi Kenneth,

Kenneth said:

The only exception is that there are a very few new anomalies on rev 3 that you should check may apply:

The rev3 chip we received is marked exactly N51822-QFAAH0-1749VA.

It is one of the anomalies mentioned in PAN v3.3.

Does it means I should not use this chip for production, and even for evaluation?

I think I should reject this module from the vendor.

Thanks,

Motti

[Kenneth]

You should not reject it unless you have checked that the description of the PAN is used in your firmware project. In general the probability is very low, but you may need to look into source code whether the specific configuration is used.

I also regommend to try the swap as I suggested.

Best regards,

Kenneth

[Motti Ng]

Hi Kenneth,

I checked my code and the specific configurations are not used.

I tried the swap and found that the module which does not advertise should be defective.

The other one module has passed our test mode (which includes a lot of SPI communications)

This Rev3 module seems functioning, but I am quite concerned about the random toggling signal on MOSI.

I checked other products that uses nRF51822 Rev3 H1, there was NO similar random MOSI toggling.

I have uploaded a CRO screenshot of the SPI signals.

Can you give me some advise where those MOSI toggling may come from?

Thanks,

Motti

[Kenneth]

Hi,

I could not find any screenshot? 

Maybe the MOSI is floating, have you tried to configure internal pull-down or use external pull-down?

Best regards,
Kenneth

[Motti Ng]

Hi kenneth,

The screenshot was added to this post above.

I tried changing MOSI to internal pull-down or external pull-down, there was nothing changed.

Refer to the screenshot, there are long pulses and short pulses.

It is found that the long pulses disappear if BLE advertising is stopped,

and Short pulses disappear if nrf_drv_spi_transfer has never been called.

Any thoughts?

Thanks,

Motti

[Kenneth]

Hi,

What would you say the failure rate is here?

It is very odd that the MOSI pin is fluctuating, are you sure nothing has changed, e.g. MISO or MOSI is swapped somehow. Poor connection or soldering? Have you measured on MOSI using analog input on the oscilloscope? You are sure CSN is high at all time?

Motti Ng said:

I tried the swap and found that the module which does not advertise should be defective.

What does this mean? Does rev 2 fail on new module? Does rev 3 work on old module?

Best regards,
Kenneth

[Motti Ng]

I am sure nothing has changed. Both rev 2 and rev 3 module were programmed with the same .hex file. They were soldered on the same PCBA and 3 pcs of rev 3 modules shows the same MOSI behaviour. I even tried to power up the module by test jig, the MOSI does fluctuate without the present of PCBA.

I have measured on MOSI using analog input. The pulses are at 3.3V-High and 0V-Low.

CSN is high at all time. CLK is always low until I send out my desired signal (as shown in my screenshot). So I do not think those fluctuations are SPI operation.

I tested 1pcs Rev2 module and 3pcs Rev3 module.

The Rev2 module is all fine.

All 3 Rev3 modules have MOSI issue. Among them 1 Rev3 modules was found not advertising. By swapping this Rev3 module to another Rev3 module, this Rev3 module is proven defective.

[Kenneth]

Hi,

I am not quite sure if we are talking about the same thing.

Can you send me a picture of rev2 and rev3 module?

Best regards,
Kenneth

[Motti Ng]

Rev 2 module:

Rev 3 module:

[Kenneth]

Hi,

I am a little unsure how to best help you on this case.

We could re-test the chips in specific if you like, just to confirm they are not damaged in some way. I assume we can also be helpful in physically swapping the nRF51822 chips between the two modules if you send them to us.

It would be interesting to know if you have tried your software on an nRF51-DK (with rev3) and if you can observe the same, that might give some indication if it's module, chip damage or revision in specific. Is there any code we can run on a nRF51-DK to replicate the issue?

Let me know your thoughts.

Best regards,
Kenneth