I couldn't find a concise summary, so I looked at the schematics (page 11 of SPF-3880_A2.pdf).
- SW802 is the main mode switch, two position.
- SW801 is the secondary switched, used if "internal boot (development) is selected.
SW1 is BOOTMODE_1, and SW2 is BOOTMODE_0. The board ships with SW1=1 and SW2=0.
| SW1 | SW2 | Mode |
|---|---|---|
| 0 | 0 | Boot from fuses |
| 0 | 1 | Serial Downloader -- load data over USB using the Type C port. |
| 1 | 0 | Internal Boot (Development) -- this is how the board was shipped for booting from eMMC0. |
| 1 | 1 | reserved |
If in internal boot mode, SW801 provides the details.
According to schematics, SW1 is BT_CFG10, SW2 is BT_CFG12, SW3 is BT_CFG13 and SW4 is BT_CFG14. The board ships with setting 0010.
| SW1 | SW2 | SW3 | SW4 | Boot Mode | Meaning |
|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0000 0000 0000 0010 |
Reserved |
| 1 | 0 | 0 | 0 | 0000 0100 0000 0010 |
Reserved |
| 0 | 1 | 0 | 0 | 0001 0000 0000 0010 |
SD/eSD boot from eSDHC1 |
| 1 | 1 | 0 | 0 | 0001 0100 0000 0010 |
SD/eSD boot from eSDHC2 |
| 0 | 0 | 1 | 0 | 0010 0000 0000 0010 |
MMC/eMMC boot from eSDHC1 As shippped |
| 1 | 0 | 1 | 0 | 0010 0100 0000 0010 |
MMC/eMMC boot from eSHDC2 |
| 0 | 1 | 1 | 0 | 0011 0000 0000 0010 |
NAND flash, 128 page block |
| 1 | 1 | 1 | 0 | 0011 0100 0000 0010 |
NAND flash, 64 page block |
| 0 | 0 | 0 | 1 | 0100 0000 0000 0010 |
QSPI |
| 1 | 0 | 0 | 1 | 0100 0100 0000 0010 |
reserved |
| 0 | 1 | 0 | 1 | 0101 0000 0000 0010 |
SPI Nor |
| 1 | 1 | 0 | 1 | 0101 0100 0000 0010 |
reserved |
| 0 | 0 | 1 | 1 | 0110 0000 0000 0010 |
reserved |
| 1 | 0 | 1 | 1 | 0110 0100 0000 0010 |
reserved |
| 0 | 1 | 1 | 1 | 0111 0000 0000 0010 |
reserved |
| 1 | 1 | 1 | 1 | 0111 0100 0000 0010 |
reserved |
Author: Terry Moore, MCCI Corporation (mcci.com). We do system software for USB and IoT, and a variety of specialized hardware products.