3.3.9 ECO revision number
To track any Engineering Change Order (ECO) fixes in the CCI-550, you can change part of the peripheral ID register using the ECOREVNUM input pins. You must tie these signals LOW unless you have an ECO from ARM®.
The ECOREVNUM[3:0] input corresponds to bits[7:4] of the Peripheral ID3 register,
MSB to MSB. Driving an input bit HIGH inverts the associated Peripheral ID3 bit.
Note ARM recommends that each of the signal drivers is distinct
and readily identifiable to facilitate possible metal layer modification.