AMBE-2000 Digital Voice Systems, Inc., AMBE-2000 Datasheet - Page 23

• Manufacturer Part Number: AMBE-2000
• Description: 2.0 - 9.6 KBPS Single ic For Toll-quality, Low Data Rate, Real Time Speech Compression
• Manufacturer: Digital Voice Systems, Inc.

4.3
The signals in Table 4-C make up the serial channel interface. The serial channel mode transfers data in and out of the
AMBE-2000™ using 16 bit words on the two data lines CHAN_RX_DATA and CHAN_TX_DATA. The selection of the
framed or unframed format of this data is made using information in Table 4-A.
Note 1:The AMBE-2000 expects an encoder packet to be read approximately every 20 msec. Following the initial
reset, wait for EPR to go low and read the initial packet (t0). 20 msec later, the next packet (t1) should be ready.
For packet t1 and all following packets use the procedure below:
1) Wait for slightly less than 20 msec.
2) Assert CHAN_TX_STB and read word on CHAN_TX_DATA.
3) If transmitted word not 0x13EC, discard it and repeat step 2.
4) If transmitted word 0x13EC, read 23 more words (rest of packet).
A new packet should be ready every 20 msec after the initial EPR high to low transition. A packet read should take place
every 20 msec. If there is a delay in the read (i.e. a packet is missed), it is recommended that the device be reset.
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CHAN_RX_DATA
CHAN_RX_STRB
CHAN_TX_DATA
CHAN_TX_STRB
CHAN_RX_CLK
CHAN_TX_CLK
Symbol
EPR
Pin
Channel Serial Mode
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Table 4-C Channel Serial Interface Pin Descriptions
Active Output/
Passive Input
Direction
Out
Out
Pin
In
In
In
In
Number
Pin
20
32
28
30
42
34
38
AMBE-2000™ Vocoder Chip
Description
Encoder Packet Ready: Following a reset, this output signal will have a high to low
transition to indicate that the encoder has a frame of data to output. The next packet
will be ready approximately 20 msec later. See Note 1.
Serial Data Input: 16 bits of channel data are input on CHAN_RX_DATA, synchronous
to CHAN_RX_CLK, with each CHAN_RX_STRB pulse.
Serial Input Clock: In coordination with CHAN_RX_STRB, CHAN_RX_DATA is
latched by the AMBE-2000™ on the falling edges of CHAN_RX_CLK.
Input (Write) Data Strobe: This signal indicates to the AMBE-2000™ when the data on
CHAN_RX_DATA will be latched by CHAN_RX_CLK. See Figure 4-B.
Serial Data Output: 16 bits of channel data are output on CHAN_TX_DATA,
synchronous to CHAN_TX_CLK, with each CHAN_TX_STRB pulse.
Serial Output Clock: In coordination with CHAN_TX_STRB, the data on
CHAN_TX_DATA is output by the AMBE-2000™ on the rising edges of
CHAN_TX_CLK.
Output (Read) Data Strobe: This signal indicates to the AMBE-2000™ when to bring
the data to the CHAN_TX_DATA pin. See Figure 4-B.
User’s Manual Version 4.0
Page 23