User guide

204 RealCT Direct API Developer Guide
Chapter 6: MVIP-95
Configuring the H.100 Bus Speed
The H.100 hardware specification supports three possible bus
speeds. These speeds control how many timeslots the streams
use as follows:
If the streams use all 128 timeslots, each carrying data at
64 Kb/s, the stream operates at 128 x 64 Kb/s = 8.192 Mb/s.
If the streams use 64 timeslots, each carrying data at
64 Kb/s, the stream operates at 64 x 64 Kb/s = 4.096 Mb/s.
If the streams use 32 timeslots, each carrying data at
64 Kb/s, the stream operates at 32 x 64 Kb/s = 2.048 Mb/s.
These different stream speeds provide compatibility with
MVIP-90, H-MVIP, and SCSA buses.
To set the bus speed, use the
MVIP95_CMD_CONFIG_STREAM_SPEED function. You set
the stream speed for the first 16 streams in groups of four, so
you would set the speed for streams 0-3 together; 4-8 together;
9-12 together; and 13-16 together. You can choose between a
stream speed of 8 (8.192 MHz), 4 (4.096 MHz), or 2 (2.048 MHz).
Streams 0-15 have a default speed of 2.048 MHz.
The last 16 streams have an undefined stream speed. They are
not available unless you assign a stream speed.
If you have several H.100 compliant boards connected in an
H.100 bus, all boards should be using a bus speed of 8 to take
full advantage of the H.100 bus. However, if you do adjust the
speed for one board, adjust all boards so they are using the same
speed.
To find out what bus speed the CT bus is using, use the
MVIP95_CMD_QUERY_STREAM_SPEED function.
Example 13 shows how to configure the streams to use the
fastest stream speed.