Rainbow Electronics DS2130Q - Manual (Page 6)

DS2130Q
041295 6/22
ADDRESS/COMMAND BYTE Figure 3
(MSB) (LSB)
- V/T A5 A4 A3 A2 A1 A0
SYMBOL POSITION NAME AND DESCRIPTION
- ACB.7 Reserved; must be zero for proper operation.
V/T ACB.6 Voice/Tone command byte select.
0 = write to Tone Generator Control register
1 = write to Voice Control register
A5 ACB.5 MSB of Device Address.
A4 ACB.4
A3 ACB.3
A2 ACB.2
A1 ACB.1
A0 ACB.0 LSB of Device Address.
VOICE CONTROL REGISTER
The Voice Control Register (VCR) determines the com-
pression/expansion bit rate and PCM data format. It
also provides power-down and algorithm reset control.
The u/A bit selects either µ -law or A-law PCM data en-
coding for PCMIN and PCMOUT pins. When u/A = 1,
µ
-Law is selected; when u/A = 0, A-Law is selected.
Compression or expansion bit rates are determined by
bits CXS1, CXS2 and CXS3. See Table 2 for the map-
ping of these bits. For the reduced bandwidth modes,
the incoming PCM data is internally filtered with a 1.7
KHz low-pass and sampled at one-half of the CPXFS/
PCMFS frequency. The PCM Bypass mode (CXS1=1,
CXS2=0 and CXS3=1) permits input PCM data at either
PCMIN or CPXIN to be routed out to CPXOUT or
PCMOUT respectively, bypassing normal compres-
sion/expansion.
Voice compression/expansion can be disabled by set-
ting CPD1 to a 1. In this mode, the compression/expan-
sion algorithm is idled and CPXOUT is tri-stated. This
mode should be used when only DTMF/tone generation
and detection are desired. When CPD1 and CPD2
(CPD2 is in the Tone Control register) are both equal to a
1, the device enters a low-power standby mode in which
all DSP operation is halted.
In this mode, the serial port
must not be operated faster than 39 KHz.
CPXRST resets the algorithm coefficients for the ex-
pansion/compression algorithm to their initial values.
CPXRST will be cleared by the device when the algo-
rithm reset is complete.
The compression/expansion loopback feature is en-
abled when CXLB is set and CPD1 is cleared. During
this loopback, no expansion or compression occurs and
input data at CPXIN is looped back to the appropriate
time slot at CPXOUT.
Compression or expansion operation is selected via the
CP/EX bit (the DS2130 cannot perform both simulta-
neously).