Digital Voice Systems AMBE-20X0 HDK, Руководство пользователя

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AMBE-20x0™-HDK Development Board
User’s Manual
(Preliminary)
Page 19
DVSI Confidential Proprietary
Section 4 – Communication via Channel Interface
When power is applied to the board, the HDK sets the configuration of the AMBE-2000 vocoder chip to
the setting as set by the dipswitches. This allows to the board to keep the configuration setting in
between power cycling or after pressing reset.
To set the HDK into AMBE Packet Format the user must connect the console output cable to a PC open
a terminal window press “#” in order to get a menu to print to the screen. This menu will indicate the
current status and configuration of the hdk. To set a new setting press the corresponding number on the
keypad and the console monitor will indicate the new configuration setting.
NOTE any setting set thru the keypad is stored in volatile memory, this means that if reset is pressed or
power is cycled any configuration settings that were set through the keypad will be lost. Anytime reset is
press or power is cycled, the HDK reverts to the configuration settings as set by the dipswitches.
“HDK Format” Packet Data Structure
Data packets sent as byte-aligned frames over the asynchronous RS-232 UART Serial interface. This
helps maintains compatibility with asynchronous 8N1 framing and synchronization if channel errors exist.
The first word is the sync element. It holds the 16-bit identification (0x13EC) of the start of the packet.
The packet sync value of the first word is always the same. The second 16 bit word contains the first
word of the compressed data. The total number of bits in the packet depends upon the voice
compression data rate. In the “HDK Format”, the total packet length will vary depending on the
compressed data rate selected. If a data rate is selected that results in the last word being not
completely filled then the HDK will add zeros to fill in the end of the word. Also, as different data rates
are selected the HDK will “auto-baud” the RS-232 baud rate. “Auto-baud” helps maintain channel
efficiency by setting the RS-232 baud rate to the lowest rate possible to accommodate the transmitted
data.
“HDK Mode” Packet Structure
Word Contents Description
0 Header / Sync Word Hex Value 0x13EC
1 Compressed Voice Channel Data
2 …
3 … Last Word for 2000 < rates < 2400 bps
… …
6 … Last Word for 4000 < rates < 4800 bps
… …
… …
…
13 Compressed Voice Channel Data Last Word for 8000 < rates < 9600 bps
Table 18 “HDK Format” Packet Structure