Digital Voice Systems AMBE-2000 User manual

The Speech Compression Specialists
Digital Voice Systems, Inc.
234 Littleton Road Tel: [phone] email: [email protected]
Westford, MA 01886 USA Fax:[phone]www.dvsinc.com
Interfacing DVSI’s AMBE-2000™ and AMBE-2020™ Vocoder Chips
with the Analog Devices AD73311 Codec
The Analog Devices AD73311 codec chip presents a simple low cost solution for use with
DVSI’s AMBE-2000™ or AMBE-2020™ vocoder chips. This application note provides
information on alternative methods of interfacing these components.
AD73311AR codec (using a 5 volt supply)
The block diagram in Figure 1 shows a sample interface between the AD73311 codec and
DVSI’s AMBE-2000™ vocoder chip. When the AMBE-2000™ or AMBE-2020™ CODEC_SEL
bits (see AMBE-2000™ or AMBE-2020™ users manual) are set for the AD73311, the vocoder
chip sends configuration words to the codec and no other configuration actions required by the
user. Configuration words are listed in Table 1.
5 V
3.3 V
SERIAL PORT ENABLE (HIGH)
16.384 MHz
U1
AMBE-2000
27
33
37
29
31
41
CODEC_RX_CLCK
CODEC_TX_CLCK
CODEC_TX_STRB
CODEC_RX_STRB
CODEC_RX_DATA
CODEC_TX_DATA
U2
AD73311AR
14
17
18
16
19
20
15
3
9
12
SCLCK
SDOFS
SDIFS
SDO
SDI
SE
MCLK
AVDD1
AVDD2
DVDD
Figure 1: The AMBE-2000™ Vocoder with the AD73311 CODEC
Register Address
(D10-D8)
Configuration Data
(D7-D0) Notes:
0x1
CRB 0x13 MCD = 1 Sets DMCLK=MCLK/2 SCD = 0 Sets SCLK=DMCLK/8
0x2
CRC 0xF9
D7 = 1 5V EN On
D6 = 1 Reference Out Enabled
D5 = 1 Reference Power On
D4 = 1 DAC Power On
D3 = 1 ADC Power On
D0 = 1 Power On
0x3
CRD 0x00 Gain set to 0
0x0
CRA 0x01 D0 = 1 Puts CODEC in Data Mode
Table 1: Configuration Data Sent to the AD73311 from the AMBE-2000 when CODEC_SEL [1-0]=01,b
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AMBE-2000™ and AMBE-2020™ Vocoder Chip Interface Applications Note May 02

AD73311AR codec (using a 3 volt supply)
It may be desirable for the AD73311 AD/DA converter to be configured for a 3-volt supply
voltage instead of a 5-volt supply voltage. The diagram and configuration procedure below
outline the details necessary in order to send alternate configuration words to the CODEC.
16.384 MHz
3.3 Volts
1/AMBE-2000
U1
27
33
37
29
31
41
CODEC_RX_CLK
CODEC_TX_CLK
CODEC_TX_STRB
CODEC_RX_STRB
CODEC_RX_DATA
CODEC_TX_DATA
U8A
12
High
U5A
SN74AHC125
2 3
1
SDI
CONTROL
AMBE-2000
U4A
SN74AHC125
2 3
1
0/DSP
3.3
Volts
U2
AD73311AR
14
17
18
16
19
20
15
3
9
12
SCLK
SDOFS
SDIFS
SDO
SDI
SE
MCLK
AVDD1
AVDD2
DVDD
DSP/Microcontroller
U3
FS
SCLK
SDO
Figure 2: The AMBE-2000™ or AMBE-2020™ Vocoder with the AD73311 Configured for 3-volt operation.
The objective of this circuit is to tri-state the output of the AMBE-2000 CODEC_TX_DATA. This
allows the DSP or Microcontroller to communicate with the AD73311 to send it the desired
configuration.
1. Configure the AMBE-2000 for operation with the AD73311 Codec. Set the CODEC_SEL
pins as shown.
CODEC_SEL [1-0] (pins 85,84) = 01,b
2. Hold the CODEC_TX_DATA lines on the AMBE-2000 in tri-state (in the circuit set the
SDI bit to 0,b) during power up.
3. While the AMBE-2000 lines are in tri-state, send the desired configuration words from
the DSP/Microcontroller/logic to the AD73311 (Reset timing constraints for the AD73311
must be met).
4. After sending the configuration words set the SDI Control bit to 1,b (SEE NOTE). This
sets the CODEC SDI line for normal operation with the AMBE-2000.
NOTE: The SDI Control bit must be set to 0 for approximately 365 msec following a hardware reset.
Page 2 of 4
AMBE-2000™ and AMBE-2020™ Vocoder Chip Interface Applications Note May 02

Register Address
(D10-D8)
Configuration Data
(D7-D0) Notes:
CRB
0x1 0x13 MCD = 1 Sets DMCLK=MCLK/2 SCD = 0 Sets SCLK=DMCLK/8
CRC
0x2 0x79
D6 = 1 Reference Out Enabled
D5 = 1 Reference Power On
D4 = 1 DAC Power On
D3 = 1 ADC Power On
D0 = 1 Power On
CRD
0x3 0x00 Gain set to 0
CRA
0x0 0x01 D0 = 1 Puts CODEC in Data Mode
Table 2: Alternate Configuration Data for the AD73311
AD73311L codec (3 volt supply)
The Analog Devices AD73311L is a low power 3 volt version of the AD73311. It is possible to
use this part with the AMBE-2000™ or AMBE-2020™ vocoder chip utilizing the method
described above for sending alternate configuration words to the AD73311 CODEC. Table 3
lists alternate control words for configuring the AD73311L for use with the AMBE-2000™ or
AMBE-2020™.
Register Address
(D10-D8)
Configuration Data
(D7-D0) Notes:
0x1
CRB 0x13 MCD = 1 Sets DMCLK=MCLK/2 SCD = 0 Sets SCLK=DMCLK/8
0x2
CRC 0x79
D6 = 1 Reference Out Enabled
D5 = 1 Reference Power On
D4 = 1 DAC Power On
D3 = 1 ADC Power On
D0 = 1 Power On
0x3
CRD 0x00 Gain set to 0
0x0
CRA 0x01 D0 = 1 Puts CODEC in Data Mode
Table 3: Configuration Data for the AD73311L
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AMBE-2000™ and AMBE-2020™ Vocoder Chip Interface Applications Note May 02

Additional Reference Material
AMBE-2000™ or AMBE-2020™ vocoder chip Users Manual
http://www.dvsinc.com/literature.htm
Application Report – Understanding Data Converters:
http://www-s.ti.com/sc/psheets/slaa013/slaa013.pdf
AD73311 - Data Sheet
http://www.analog.com/productSelection/pdf/AD73311_b.pdf
AD73311L - Data Sheet
http://www.analog.com/productSelection/pdf/AD73311L_a.pdf
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AMBE-2000™ and AMBE-2020™ Vocoder Chip Interface Applications Note May 02