RALCWI Vocoder
CMX608/CMX618/CMX638
5.10. C-BUS Registers
5.10.1.
Command Registers
RESET register address $01
This register has no data associated with it. Writing to it (by the General Reset command) will
reset the device and restore all the default settings. All registers are cleared to '0' on reset, unless
marked otherwise. As a result, the BIAS pin is powered down and the voltage on the external
decoupling capacitor (C14) will decay to VSS. The crystal oscillator is unaffected by writing to the
RESET register (a "soft" reset). Instead, it is powersaved by connecting the ENABXTAL pin to VSS.
SYNC register address $02
This register has no data associated with it. Writing to it will synchronise the Vocoder with the host
on the next rising edge of the CSN signal. It performs the same function as the SYNC input pin.
Either SYNC source may be used as they are ORed together.
SYNCCTRL register address $04
7
0
6
0
5
0
4
0
3
2
1
0
PERIOD
CONTROL
Bits 0 and 1
CONTROL
These two bits control the Vocoder synchronisation according to the table below.
Bit 1
Bit 0
Description
0
0
1
0
1
Internal synchronisation. SYNC pin 25 is set as an input but unused. This is
the default setting for this pin. This pin must be tied to '0' or '1' by the user.
Internal synchronisation. SYNC pin 25 is set as an output, and a sync pulse
is produced to allow an external device to synchronise with this one.
Internal synchronisation. SYNC pin 25 is set as an input but unused.
SYNC pin 25 must be tied to '0' or '1'.
External synchronisation. SYNC pin 25 is set as an input. A sync pulse
should be applied to this pin or this pin should be tied low and a write to the
SYNC register ($02) will act as a sync pulse.
0
1
1
When set for external synchronisation, the period between positive edges of the sync pulse
applied to the SYNC pin, or the C-BUS writes to the SYNC register, should be 20ms or a multiple
thereof. The next sync pulse after writing this register will be used as the reference. The pulse
width must be at least 62.5µs. If the synchronisation input is provided by C-BUS, then both bits
should be set to '1' and SYNC pin 25 should be connected to '0' (VSS).
When the bits are set to '01', a positive-going sync pulse is output from the SYNC pin with a pulse
width of 125µs, except in the case where bits 2 and 3 are both '0', where an 8kHz square wave is
output from the SYNC pin instead.
Note 1: The CODEC must be taken out of powersave by setting bit 1 in the POWERSAVE register
($09) for sync pulses to be produced.
Note 2: If moving between 20/40/60ms pulse settings, the 8kHz square-wave setting must be
selected in between.
2012 CML Microsystems Plc
33
D/608_18_38/10
CMLMICRO [ CML MICROCIRCUITS ]
