Here is the Nissan SIEMENS ECU pin code calculator free download link.
Free download Nissan SIEMENS Code calculator
How to use Nissan NATS Calculator?
Locate immobilizer control unit label, and record Date code and Encrypted PIN
Here it in picture show as
Input date code and encrypted pin to NATS Siemens calculator as below show
Then click “Submit”
You will get PIN code:6572