SPRUJ55D September 2023 – July 2025 AM263P2 , AM263P2-Q1 , AM263P4 , AM263P4-Q1
The ECCM block stores the Authentication and/or ECCM in the target memory or flash. This creates the need to translate the address from the requester to the target. The translation is fixed for a given target, that is, if a target contains ECCM, the entire target reserves an ECCM data word for each 32 byte block. If a target has only Authentication, the target reserves an Authentication word for each 32 byte block. If the target has both Authentication and ECCM that target reserves up to 5 data words for each 32 byte block.
So for a given input block address, the target address the block is stored at is dependent on the configured mode and not the region mode. That is, if you have any authentication modes enabled and ECCM enabled, the external block always reserves a MAC word and an ECCM word regardless of whether you are in a region with Authentication or ECCM. The MAC word is only used in regions that are authenticated and the ECCM is only used in regions that have ECCM.
The target address equation for a given input address is defined as follows. The configuration mode for a given target is not ever expected to change once setup.
Where variables:
The following table shows some example configurations and available blocks
| ECCM Mode | Authentication Mode | MAC Size | Target Block Address | 64MB blocks Available |
|---|---|---|---|---|
| N | N | N/A | InputAddress/32*32 | 64 |
| Y | N | N/A | InputAddress/32*36 | 56.8 |
| N | Y | 4 bytes | InputAddress/32*36 | 56.8 |
| Y | Y | 4 bytes | InputAddress/32*40 | 51.2 |
| Y | Y | 8 bytes | InputAddress/32*44 | 46.5 |
| Y | Y | 16 bytes | InputAddress/32*52 | 39.3 |
It is important to note that if a target is configured to have ECCM or Authentication but not both, the total blocks available is reduced by 11%. That is, 11% of the flash is reserved for Authentication or ECCM data regardless if any regions for ECCM or authentication are used.
If the target is configured for both ECCM and Authentication (4B MAC), the total blocks are reduced by 20%. That is, 20% of the flash is reserved for Authentication and ECCM regardless if any regions for ECCM or authentication are used.