Board Addressing
Each Opera Cake has a numeric address set by optional jumpers installed on header P1. The default address (without jumpers) is 0. The --list or -l option can be used to list the address(es) of one or more Opera Cakes installed on a HackRF One:
hackrf_operacake -l
The address may be set to any number from 0 to 7 by installing jumpers across the A0, A1, and/or A2 pins of header P1.
| Address | A2 Jumper | A1 Jumper | A0 Jumper | 
|---|---|---|---|
| 0 | No | No | No | 
| 1 | No | No | Yes | 
| 2 | No | Yes | No | 
| 3 | No | Yes | Yes | 
| 4 | Yes | No | No | 
| 5 | Yes | No | Yes | 
| 6 | Yes | Yes | No | 
| 7 | Yes | Yes | Yes | 
When configuring an Opera Cake, the address may be specified with the --address or -o option:
hackrf_operacake -o 1 -a A1 -b B2
If the address is unspecified, 0 is assumed. It is only necessary to specify the address if the address has been changed with the addition of jumpers, typically required only if multiple Opera Cakes are stacked onto a single HackRF One.