Texas Instruments OMAP5912 Reference Manual page 1262

6.6.12 Autobauding Mode
SPRU760B
It is assumed that software flow control and hardware flow control will never
be enabled simultaneously.
In autobaud mode, UART extracts transfer characteristics (speed, length and
parity) from an AT command. These characteristics are used to receive data
following an at and to send data.
Here are valid AT commands:
AT DATA
AT DATA
A/
a
The line break during the acquisition of the sequence AT is not recognized and
echo functionality is not implemented in hardware.
A/ and a/ are not used to extract characteristics, but they have to be recognized
because of their special meaning. They are used to instruct the software to
repeat the last received AT command. Therefore, an a/ always comes after an
AT, and transfer characteristics are not expected to change between an AT and
an a/.
As soon as a valid at (AT) is received, it and all subsequent data are saved into
FIFO, including final <CR> (0x0D). Then, the autobaud state machine waits
for the next valid AT command. If an a/ (AI) is received, it is saved into FIFO
and the state machine waits for next valid AT command.
Upon the first successful detection of the baud rate, the UART activates an
interrupt to signify that the AT(upper- or lowercase) sequence has been
detected. The UASR register reflects the correct settings for the baud rate that
has been detected. The interrupt activity continues in this fashion each time
a subsequent character is received. Therefore, it is recommended that the
software enable the RHR interrupt when using the autobaud mode.
The following settings are detected in autobaud mode with a module clock of
48 MHz:
Speed:115.2K bauds, 57.6K bauds, 38.4K bauds, 28.8K bauds, 19.2K
-
bauds, 14.4K bauds, 9.6K bauds, 4.8K bauds, 2.4K bauds, or 1.2K bauds
Length: 7 or 8 bits
-
Parity: Odd, even, or space
-
Note:
The combination of 7-bit character + space parity is not supported.
<CR>
<CR>
UARTs
Serial Interfaces 197