31.2.3 Definitions
The Flash Controller, Write (FCW) supports programming operations (writes/erases) for on-chip Flash memory. This device’s Flash memories have 256-bit read data width and 64-bit write data width. There are extra bits which the FCW uses to implement Error Correction Code (ECC) for single error correct (SEC) and double error detect (DED).
A Flash panel is a single Flash memory block. This device has a dual panel Flash memory system, consisting of two identical 4M, 2M, or 512k Byte panels. The structure of each Flash panel is shown in the following figure.
For the purpose of the Flash Controllers a “Word” is defined as 4-bytes or 32-bits. A Write Word (WW), the native write width of the Flash, is a Double Word, DWord, of 8-bytes. A Read Word, the native read width of the Flash, is a Quad Double Word, QDWord, of four Write Words or 32-bytes. “Flash Words” as described in this section are Read Words.
Flash panels contain 16 extra bits per Read Word to support ECC. These bits are among the four Write Words of a Read Word (i.e. 4 extra bits/Write Word). Therefore, a Write Word is really 64 data bits and 4 ECC bits. Referring to DWords, Flash Words, QDWords implies the associated ECC bits also.
A Flash panel is divided into three logical Flash partitions:
- Program Flash Memory (PFM).
- Boot Flash Memory (BFM).
- Configuration Flash Memory (CFM).
The dual panel system provides two sets of logical Flash partitions, of which the PFM and BFM are identical, but CFM usage varies slightly between panels.