AMBE2000 Datasheet, PDF (21/47 Pages) List of Unclassifed Manufacturers – VOCODER CHIP

AMBE-2000™ Vocoder Chip
User’s Manual Version 3.0
4.3 Channel Serial Mode
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
formatted or unformatted format of this data is made using information in Table 4-A.
Table 4-C Channel Serial Interface Pin Descriptions
Pin
Symbol
EPR
Pin
Direction
Out
Pin
Number
20
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.
CHAN_RX_DATA
In
32
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.
CHAN_RX_CLK
In
Serial Input Clock: In coordination with CHAN_RX_STRB,
28
CHAN_RX_DATA is latched by the AMBE-2000™ on the falling edges of
CHAN_RX_CLK.
CHAN_RX_STRB
In
Input (Write) Data Strobe: This signal indicates to the AMBE-2000™
30
when the data on CHAN_RX_DATA will be latched by CHAN_RX_CLK.
See Figure 4-B.
CHAN_TX_DATA
Out
Serial Data Output: 16 bits of channel data are output on
42
CHAN_TX_DATA, synchronous to CHAN_TX_CLK, with each
CHAN_TX_STRB pulse.
CHAN_TX_CLK
In
Serial Output Clock: In coordination with CHAN_TX_STRB, the data on
34
CHAN_TX_DATA is output by the AMBE-2000™ on the falling edges of
CHAN_TX_CLK.
CHAN_TX_STRB
Active
Output/
Passive
Input
38
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.
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.
page 21
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