Semtech LR1121 - Deriverootkeysandgetpin; Table 11-5: Deriverootkeysandgetpin Command (Standard); Table 11-6: Deriverootkeysandgetpin Response

LR1121
User Manual Rev 1.1
UM.LR1121.W.APP Mar 2023
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11.2.3 DeriveRootKeysAndGetPin
Command DeriveRootKeysAndGetPin(...) derives the AppKey and NwkKey root keys, and calculates the
corresponding PIN, required to claim a device on the Semtech Join Server. It is a very versatile function with a standard use
and a more advanced use, as described in the coming sections:
Three use-cases are possible:
• Standard: Uses the pre-provisioned ChipEui, DevEui and use the Semtech Join Server.
• Advanced: The DevEui and/or the JoinEui can be personalized, whilst still using the Join Server.
• Alternate: AppKey and NwkKey are forced by the user, and the Join Server can’t be used.
11.2.3.1 Standard Use
PIN: Coded on 4 bytes, in big endian format
In the standard use-case, the ChipEui is used as LoRaWAN DevEui, SemtechJoinEui is used as LoRaWAN JoinEui, and
therefore no specific action should be taken. The host should:
1. Call the DeriveRootKeysAndGetPin() command with no argument.
2. Read the SemtechJoinEui (GetSemtechJoinEui() command) and assign it to a JoinEui variable.
3. Read the ChipEui (GetChipEui() command) and assign it to a DevEui variable.
4. Execute the Join procedure using the elements that have just been read.
5. At the reception of a valid Join Answer, all lifetime and session keys can be derived according to the required LoRaWAN
Standard.
The device must also be claimed on the Semtech Join Server for the Join Request to be accepted.
Table 11-5: DeriveRootKeysAndGetPin Command (Standard)
Byte 0 1
Data from Host 0x01 0x27
Data to Host Stat1 Stat2
Table 11-6: DeriveRootKeysAndGetPin Response
Byte 0 1 2 3 4
Data from Host 0x00 0x00 0x00 0x00 0x00
Data to Host Stat1 PIN(31:24) PIN(23:16) PIN(15:8) PIN(7:0)