30.6.8 Silent Access
When enabled (SECCTRL.SILACC = 1), the silent access feature allows to store data and their 1's complement in one Data Flash row (selected by SECCTRL.TEROW), thus reducing the overall data reading noise, as always the same number of '0' and '1' will be read for each read access.
When Silent Access is enabled, the logical size of the TEROW Flash row is divided by two to store each byte of Data and its 1’s complement (CompData) in the whole physical TEROW size.
The data stored in the selected TEROW must be accessed using the logical mapping shown in the TEROW logical mapping table.
| Byte 63 | Byte 62 | Byte 61 | … | Byte 3 | Byte 2 | Byte 1 | Byte 0 | Page |
|---|---|---|---|---|---|---|---|---|
| Data | Data | Data | Data | Data | Data | Data | Data | 0 |
| Data | Data | Data | Data | Data | Data | Data | Data | 1 |
| Reserved | Reserved | Reserved | Reserved | Reserved | Reserved | Reserved | Reserved | 2 |
| Reserved | Reserved | Reserved | Reserved | Reserved | Reserved | Reserved | Reserved | 3 |
The physical mapping of the TEROW, when silent access feature is enabled, is represented in the TEROW physical mapping table:
| Byte 63 | Byte 62 | Byte 61 | … | Byte 3 | Byte 2 | Byte 1 | Byte 0 | Page |
|---|---|---|---|---|---|---|---|---|
| CompData | Data | CompData | Data | CompData | Data | CompData | Data | 0 |
| CompData | Data | CompData | Data | CompData | Data | CompData | Data | 1 |
| CompData | Data | CompData | Data | CompData | Data | CompData | Data | 2 |
| CompData | Data | CompData | Data | CompData | Data | CompData | Data | 3 |
The NVMCTRL automatically manages both scrambling and differential data storage if the tamper row resides in the secure Data Flash area and both are enabled (SECCTRL.DSCEN = 1 and SECCTRL.SILACC = 1).