crystal trimming OTP parameters on nRF70

[Adam M]

Our production facility has some concerns about using the OTP parameters.  Specifically, they are concerned about writing the wrong value and then needing to scrap the device.

The only parameter that they are writing is opt_write_params CALIB_XO

I understand this is a one-time operation per bit (1 can transfer to 0, but not back to 1), based on this page: https://docs.nordicsemi.com/bundle/nan_043/page/APP/nan_043/otp_programming.html

I see there is also a large number of commands labelled "retrim", and 15 PRODTEST.TRIMxx registers in the OTP memory.  I cannot find any documentation on these.  Are they at all related to the frequency trimming?  Do they allow for multiple write processess if an error is made?

[Håkon Alseth]

Hi,

 

Our production facility has some concerns about using the OTP parameters.  Specifically, they are concerned about writing the wrong value and then needing to scrap the device.

The only parameter that they are writing is opt_write_params CALIB_XO

Apart from the very first two steps here:

https://docs.nordicsemi.com/bundle/nan_043/page/APP/nan_043/otp_programming.html

 

This is the only writing to OTP that is strictly required to ensure that you're within the requirements for both 2.4 GHz (+/- 25 ppm) and 5 GHz (+/- 20 ppm), as set by the Wi-Fi Alliance.

 

I understand this is a one-time operation per bit (1 can transfer to 0, but not back to 1), based on this page: https://docs.nordicsemi.com/bundle/nan_043/page/APP/nan_043/otp_programming.html

This is correct. You can change a '1' to '0', but not the other way around.

 

I see there is also a large number of commands labelled "retrim", and 15 PRODTEST.TRIMxx registers in the OTP memory.  I cannot find any documentation on these.  Are they at all related to the frequency trimming?  Do they allow for multiple write processess if an error is made?

These are non-documented and written during our production. These should not be overwritten or manipulated, as they are related to the physical parameters of the radio.

 

Kind regards,

Håkon