CMX7164 Datasheet, PDF (33/146 Pages) CML Microcircuits – Automatic frame sync detect

CMX7164 Multi Mode Modem
CMX7164
C-BUS Operation
Data/Control - $48, $49
and $4A write)
Write $0033 to Rx
Tracking - $66 write
Write $0401 to Modem
Mode and Control - $6B
write
-
Action
Select tracking modes
Start reception
Apply input signal
Poll the IRQ Status -
$7E read register for bit
8 – Cmd Done = 1
Read the Receive FIFO
Data Byte (see Receive
FIFO Data/Control -
$4C, $4D, $4E read) 4
times
Wait for data
Retrieve the received
data
-
End of reception
Description
Selects automatic I/Q dc offset correction and
symbol timing tracking
Initiates a frame sync search, searching for
Frame Sync 1. Once it is detected then Rx data
will be made available.
The input signal should contain preamble,
Frame Sync 1 and then raw data. The frame
sync should be detected and Rx data made
available
This indicates that the 4 data bytes requested
have been received and are available
Data is read from the Receive Data FIFO. Once
4 data bytes are read the IRQ Status register
may be polled again to check if more data is
available if required, and then those data bytes
read. This step may be repeated as many times
as needed
Once enough data has been received a mode
change (using the Modem Mode and Control -
$6B write register) will stop reception or start
searching for another frame sync.
The procedure described above can be adapted, making reception of different numbers of bytes, bits or
coded blocks possible. The registers used for basic transmission and reception are:
 13.1.18 Modem Mode and Control - $6B write
 13.1.37 IRQ Status - $7E read
 13.1.3 Modem Command FIFO Data/Control - $48, $49 and $4A write
 13.1.26 Receive FIFO Data/Control - $4C, $4D, $4E read
 13.1.4 FIFO Control - $50 write
 13.1.15 Rx Tracking - $66 write
7.4.3 Device Configuration (Using the Programming Register)
While in Idle mode the Programming register becomes active. The Programming register provides access
to the Program Blocks. Program Blocks allow configuration of the CMX7164 during major mode change.
Features that can be configured include:
 Flexible selection of Baud rates, from 2k to 20k baud
 Pre-amble and frame syncs to be using in transmit and receive
 Selection of Automatic control of 4 x GPIO and the RAMDAC during transmission
 Configuration of RAMDAC profile
 Configuration of RSSI averaging
 Configuration of the carrier sense window and thresholds
 Configuration of System Clock outputs
 Configuration of SPI Thru-Port rate and word format
 Configuration of AGC commands using the SPI Thru-Port.
Full details of how to configure these aspects of device operation are given in section 13.2 in the User
Manual.
 2015 CML Microsystems Plc
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