Specifications

AN93
102 Rev. 0.8
Figure 22. Si2457/Si3000 Connection
To use voice mode register U71 and U59 must be
properly configured.
Setting U59 = 0001h enables the Si24XX TDMA
interface. When U71 is set to the value 0011h a 16-bit
voice sample will be transmitted from the Si3000
through the Si2493/57/34/15/04 and DAA to the remote
device. Likewise, an analog signal from the remote
device will pass through the DAA where it is converted
to a 16-bit voice sample, the Si24XX and finally the
Si3000 where it is converted back to the analog receive
signal.
The modem must be the master, and it outputs FSYNC
and MCLK to the Si3000. In this example, the Si3000
has its digital TDMA interface configured as the Slave
Serial Mode by adding a 50 kΩ pull-down resistor to
SDO pin and a pull-up 50 kΩ resistor to SCLK pin. In
this mode, the Si3000’s MCLK is driven by the
2048 kHz clock from Si2493/57/34/15/04. The FSYNC
has an 8 kHz pulse input. The bit clock is 2048/
8 = 256bits per frame sync. Refer to Si3000
documentation for further details.
To send control information to Si3000, the Si2493/57/
34/15/04 modem chip provides a PCM control port
0x004B that allows user to send control words across
by using the AT memory write command. See Table 76
for details. Wait for the “OK”, approximately 300 msec,
after each command. When a connection is established,
the “AT.T” command is used to generate the DTMF tone
of a number, e.g. ATDT3<CR> will generate a number 3
DTMF tone without the need of an external DTMF
generator.
TXD
ESC
RXD
INTb
CTSb
AOUT
RTSb
RIb
DCDb
SPKR_R
MIC_BIAS
HDST
XTALI
XTALO
C1A
C1B
SPKR_L
LINEO
LINEI
MIC_IN
RESETb
VDD
VDD
VDD
NOTE: D6 (PIN 4) MUST NOT HAVE PULLDOWN RESISTOR
C52
U3
Si2457/34/15/04
CLKIN/XTALI
1
XTALO
2
CLKOUT/EECS/A0
3
D6
4
VD3.3
5
GND
6
VDA
7
RTS/D7
8
VDB
19
GND
20
VD 3.3
21
C2A
13
C1A
14
ESC/D3
22
DCD/D4
23
EECLK/D5
24
CTS/CS
11
RXD/RD
9
TXD/WR
10
RESET
12
RI/D1
17
EESD/D2
18
AOUT/INT
15
INT/D0
16
Si3000
MCLK
7
SCLK
8
FSYNC
6
SDI
4
SDO
5
RESET
9
LINEI
11
MIC_BIAS
2
MIC_IN
10
LINEO
15
SPKR_L
16
SPKR_R
1
HDST
3
VD
12
VA
13
GND
14
R61
0
C51 C53
R62
47 k
C66
0.1 uF
C50
R63
47 k
C68
0.1 uF