Bootstrap
The ConnectCore 93 module can be configured to boot from different devices and interfaces. The boot mode can be selected in two ways:
• Through the boot mode pins (recommended for development).
• Overridden by fuses (recommended for production).
When using the boot mode pins, the boot mode is determined by the binary value stored in the internal BOOT_MODE register. The boot mode is initialized by sampling the BOOT_MODE[3:0] inputs on the rising edge of POR_B. After these inputs are sampled, the subsequent states do not affect BOOT_MODE internal register value.
The BOOT_MODE[3:0] bits are available in the following signals of the SOM:
|
Signal |
Boot mode |
|---|---|
|
BT_UART1_TX |
BOOT0 |
|
BT_UART1_RTS |
BOOT1 |
|
SPI1_CS0 |
BOOT2 |
|
SPI1_SCK |
BOOT3 |
Note BT_UART1_RTS (BOOT1) has an internal pull-up to set the module to boot from the on-module eMMC by default.
The following table lists the different boot modes available on the ConnectCore 93 module:
|
BOOT core |
BOOT_MODE[3:0] |
Boot mode |
|---|---|---|
|
Cortex-A55 |
0000 |
Internal fuses |
|
0001 |
Serial downloader |
|
|
0010 |
USDHC1 8-bit eMMC 5.1 |
|
|
0011 |
USDHC2 47-bit SD3.0 |
|
|
0100 |
FlexSPI serial NOR |
|
|
0101 |
FlexSPI serial NAND 2K page |
|
|
0110 |
Infinite loop |
|
|
0111 |
Test mode |
|
|
Cortex-M33 |
1000 |
Internal fuses |
|
1001 |
Serial downloader |
|
|
1010 |
USDHC1 8-bit eMMC 5.1 |
|
|
1011 |
USDHC2 47-bit SD3.0 |
|
|
1100 |
FlexSPI serial NOR |
|
|
1101 |
FlexSPI serial NAND 2K page |
|
|
1110 |
Infinite loop |
|
|
1111 |
Test mode |
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