CMX7163 QAM Modem
CMX7163
See:
10.1.4 FIFO Control - $50 write
10.1.28 Internal Buffer Fill Level - $70 read.
Note: The Command FIFO and Command Buffer will automatically be flushed when a carrier sense
attempt to transmit results in the CMX7163 reverting to receive mode. This is to avoid accidentally
processing transmit commands pre-loaded by the host as receive commands. This is the only situation in
which the FIFOs or buffers will be flushed other than by direct host instruction.
7.4.15 Raw Data Transfer
When transferring raw data the FIFO Control byte indicates the amount of data that will be transferred in a
block before the CMX7163 interrupts the host. Byte and bit-wise transfers are possible, providing the
facility to transmit or receive a burst of arbitrary length, not just a whole number of bytes. It is suggested
that data is transferred in the maximum size blocks possible until the end of a burst - where the remaining
bits, or bytes can be transferred in a single transaction of the required size.
When using byte wise or bit wise transfers the most significant bit of the data byte is transmitted (or
received) first. When using bit wise transfers with a bit count of less than 8 the most significant bits are
used. In all cases the bits are combined into symbols according to the selected modulation type.
It is also possible to ignore the concept of blocks of data whilst in raw mode. Instead, a transmission can
just be treated as a series of bytes to transmit and FIFO levels/level IRQs used to manage the data flow.
Likewise in receive the host can request continual data reception and the resulting bytes will be placed in
the Rx Data FIFO. FIFO levels and level IRQs may be used to manage the data flow. This mode provides
the ability to simply stream (using streaming C-BUS if desired) multiple bytes into or out of the CMX7163
as FIFO content allows.
7.4.16 Formatted Data Transfer
When the transfer of formatted data is selected by the Modem Mode and Control - $6B write register the
FIFO Control byte indicates the block type to use in either sending or decoding the data. The block type
dictates the format or quantity of data transferred, including how error detection and correction bits are
added to the over air data stream.
7.4.17 Pre-loading Commands
It is advisable to pre-load data into the Command FIFO before transmission begins, or to pre-load receive
data commands into the Command FIFO prior to frame sync reception.
7.4.18 GPIO Pin Operation
The CMX7163 provides 4 x GPIO pins, each pin can be configured independently as automatic/manual,
input/output and rising/falling (with the exception of the combination automatic + input function which is
only allowed for GPIOA).
Pins that are automatic outputs become part of a transmit sequence and will automatically switch, along
with the RAMDAC – AuxDAC1 (if it is configured as automatic) during the course of a burst. Pins that are
manual are under direct user control. When automatic, a rising, or a falling event at the start or end of
transmission will cause the specified GPIO to be switched high or low accordingly.
GPIOA may be configured as an automatic input. This means that any attempted transmission will wait
until GPIOA input is high (if rising is selected) or low (if falling is selected).
See:
0
P4.8: Set legacy timing mode
2014 CML Microsystems Plc
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