SPRABA5D January 2014 – January 2019 AM1802 , AM1802 , AM1806 , AM1806 , AM1808 , AM1808 , AM1810 , AM1810
NOR (or parallel Flash) boot happens from a NOR Flash device connected to the external memory interface (EMIFA) peripheral on EMA_CS[2]. For this boot mode, the bootloader configures EMIFA for 8-bit access and reads the first word from the NOR Flash. This first word indicates if the NOR Flash should be accessed in 16-bit or 8-bit mode, as well as which boot method to be used. This word is interpreted as shown in Figure 1
The NOR boot configuration word register is shown in Figure 1 and described in Table 1.
| 31 | 12 | 11 | 8 |
| Reserved | COPY |
| 7 | 6 | 5 | 4 | 3 | 1 | 0 |
| Reserved | METHOD | Reserved | ACCESS | ||||
| Bit | Field | Value | Description |
|---|---|---|---|
| 31-12 | Reserved | 0 | Reserved |
| 11-8 | COPY | Length of data to copy from the base of the NOR Flash to the base of the On-chip RAM. This value is used only for the Legacy NOR boot method. | |
| 0x00 | 1 KB | ||
| 0x01 | 2 KB | ||
| ... | |||
| 0x0E | 15 KB | ||
| 0x0F | 16 KB | ||
| 7-6 | Reserved | 0 | Reserved |
| 5-4 | METHOD | Boot method | |
| 0x0 | Legacy NOR boot | ||
| 0x1 | Direct NOR boot | ||
| 0x2 | AIS NOR boot | ||
| 3-1 | Reserved | 0 | Reserved |
| 0 | ACCESS | EMIFA access mode | |
| 0x0 | 8-bit access | ||
| 0x1 | 16-bit access |
If ACCESS == 0x1, bootloader reconfigures EMIFA for 16-bit access before using specified boot METHOD to boot from NOR. The default configuration of the bootloader is for an 8-bit access.