Block
0
Block
1
Block
2
Block
3
Block
24
...
...
Block
N
...
...
Start searching at block 0
If no magic number found or
MMC/SD read error detected
If no magic number found or
MMC/SD read error detected
If no magic number found or
MMC/SD read error detected
If no magic number found or
MMC/SD error on boot,
restart MMC/SD boot
11.2.3 UART Boot Mode
ARM ROM Boot Modes
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Figure 11-12. Descriptor Search for ARM MMC/SD Boot Mode
If the state of BTSEL[1:0] pins at reset is 11, then the UART boot mode executes.
This mode enables a small program, referred to here as a user boot loader (UBL), to be downloaded to
the on-chip ARM internal RAM via the on-chip serial UART and executed. A host program, (referred to as
serial host utility program), manages the interaction with RBL and provides a means for operator feedback
and input.
The UART boot mode execution assumes the following UART settings:
Time-Out
500 ms, one-shot
Serial RS-232 port
115.2 Kbps, 8-bit, no parity, one stop bit
Command, data, and checksum format
Everything sent from the host to the device UART RBL must be
in ASCII format.
164
Boot Modes
SPRUFX7 – July 2008