How can I identify a Lepton 2 from a Lepton 3? Is there a sequence in a serial number that is readable? Is there a register with an ID of some kind?

The “SYS Scene ROI Select” command is common to both Lepton 2 and 3. The ROI coordinates can be read from the telemetry lines over VoSPI, if telemetry is explicitly enabled, or by using the CCI command over i2c.

The software default values for the LEP_GetSysSceneRoi command are set to the entire array and therefore indicate the array size (80x60 for Lepton 2 or 160x120 for Lepton 3), so the user can distinguish the resolution.

For example: Lepton 3: (startCol,startRow,endCol,endRow) = 0,0,159,119 Lepton 2: (startCol,startRow,endCol,endRow) = 0,0,79,59

The Lepton part number can also be read using the CCI bus. The command for this is also common to all Leptons. This allows very specific verification.

For example: 500-0659-XX = Lepton 2.0 500-0726-XX = Lepton 3.0