Digital Line to POTS Interface
CMX605
1.5.8
‘C-BUS’ Interface
This block provides for the transfer of data and control or status information between the CMX605’s
internal registers and the µC over the ‘C-BUS’ serial bus. Each transaction consists of a single Register
Address byte sent from the µC which may be followed by a single data byte sent from the µC to be
written into one of the CMX605’s Write Only Registers, or a single byte of data read out from one of the
CMX605’s Read Only Registers, as illustrated in Figure 4.
Data sent from the µC on the Command Data (COMDATA) line is clocked into the CMX605 on the rising
edge of the Serial Clock (SERCK) input. Reply Data (REPDATA) sent from the CMX605 to the µC is
valid when the Serial Clock is high. The interface is compatible with the most common µC serial
interfaces such as SCI, SPI and Microwire, and may also be easily implemented with general purpose µC
I/O pins controlled by a simple software routine. See Figure 8 for detailed ‘C-BUS’ timing requirements.
Figure 4 ‘C-BUS’ Transactions
©
2001 Consumer Microcircuits Limited
13
D/605/6
CMLMICRO [ CML MICROCIRCUITS ]
