2.9.1.7.9 SD Card/e.MMC Memory Boot Configuration (Second Word)
This word is the second word used to add an external SD card/e.MMC Flash memory in the boot sequence. Its content allows to control the check of the Card Detect pin by the ROM Code.
Warning: To avoid any
malfunctioning, the user must not write the "DO NOT USE (DNU)" bits.
| Name: | MEM_CFGx[1] |
| Bit | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | |
| DNU | DNU | DNU | DNU | DNU | DNU | DNU | DNU | ||
| Access | |||||||||
| Reset |
| Bit | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | |
| DNU | DNU | DNU | DNU | DNU | DNU | DNU | DNU | ||
| Access | |||||||||
| Reset |
| Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
| WPKEY[7:0] | |||||||||
| Access | |||||||||
| Reset | |||||||||
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| USE_CD | DNU | DNU | DNU | DNU | DNU | DNU | DNU | ||
| Access | |||||||||
| Reset |
Bits 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 – DNU DO NOT USE
Bits 15:8 – WPKEY[7:0] Write Protect Key
| Value | Name | Description |
|---|---|---|
| 0x96 | PASSWD | If any other value is written in this field, all other bit values are ignored. |
Bit 7 – USE_CD Use a Card Detect Pin
| Value | Description |
|---|---|
| 0 | Use Card Detect disabled: the ROM code does not use any card detect pin and directly tries to boot from the memory connected to the SDMMC controller. |
| 1 | Use Card Detect enabled: the ROM code checks the state of the card detect pin. If the pin level is 0, the ROM code tries to boot from a memory connected to the SDMMC interface. If the pin level is 1, the ROM code skips the boot on SDMMC and jumps to the next interface in the boot sequence. |