RALCWI Vocoder
CMX608/CMX618/CMX638
5.10.5.
16-bit Read-Only Registers
PLEVEL register address $31
15
0
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Peak Level
This read-only register contains the peak sample value of the last 20ms frame of audio collected
for encoding. This peak sample value will be available for every 20ms frame, regardless of
whether multiple frame or single frame format is selected. Bit 6 of the STATUS register ($40) will
be set to '1' (and a C-BUS interrupt generated, if enabled) when this register is updated. This value
is only updated when the facility is turned on, by writing $09 to the service request (SVCREQ)
register ($0E). The audio level should not be allowed to limit: for single-ended operation this can
be ensured by keeping the Peak Level below 16384, i.e. bit 14 of the PLEVEL register should not
become set to '1'.
DFRAMEDATA register address $37
15
Type
14
13
X
12
X
11
10
9
8
Data
7
6
5
4
3
2
Data
1
0
This read-only register contains extra information about the last 20ms frame of audio that was
decoded. The data in this register becomes valid after bit 2 in the STATUS register ($40) is set. If
this data is required, it should be read as soon as possible after it becomes valid. When decoding
multi-frame packets, once one frame is decoded, then the next frame will be processed. For
packets of voice frames, this will happen at a rate of approximately once every 6ms, but for
packets of single tones or DTMF, the rate will be approximately once every 300µs.
The Vocoder can detect frames containing either voice, DTMF, or single tones depending on
which bits are set in the VCTRL register ($11). If the Vocoder is set up to detect DTMF and/or
single tones in the vocoded frames, the DTMF code or the single tone frequency will be reported in
this register.
Bits 0 to 11
Data
This field contains either the DTMF code (bits 0 to 3) or the single tone frequency
that was detected in the audio stream.
Bits 12 to 13 Reserved. The value of these two bits should be ignored.
Bits 14 to 15 This field indicates what sort of data is contained in the data field, as shown in the
Type
table below:
Bit 15
Bit 14
Data Type
0
0
0
1
The frame was encoded audio. The data field should be ignored.
The frame contained DTMF. The data field contains the DTMF code in bits 0
to 3 (bit 3 is the msb). All other bits should be ignored. The format of the
DTMF data is specified by bit 7 (DTMFF) of the VCFG register ($07).
Please refer to section 6.2 for the bit patterns.
1
1
0
1
The frame contained a single tone. The data field contains the single tone's
frequency in Hz. The frequency value has a resolution of 32Hz and bit 11 is
the msb.
Not used.
2014 CML Microsystems Plc
51
D/608_18_38/11
CMLMICRO [ CML MICROCIRCUITS ]
