Making Connections In The Sru - Analog Devices ADSP-21261 SHARC Hardware Reference Manual

Making Connections in the SRU

As described previously, the SRU is similar to a set of patch bays. Each bay
routes a distinct set of outputs to compatible inputs. These connections
are implemented as a set of memory-mapped registers with a bit field for
each input. The outputs are implemented as a set of bit encodings. Con-
ceptually, a patch cord is used to connect an output to an input. In the
SRU, a bit pattern that is associated with a signal output (shown as item 1
in Figure 12-11) is written to a bit field corresponding to a signal input
(shown as item 2 in
The memory-mapped SRU registers are arranged by groups, referred to as
Group A through Group F and described in
ters" on page A-113. Each group has unique encodings for its associated
output signals and a set of Configuration registers. For example, Group A
is used to route clock signals. Four memory-mapped registers,
, contain 5-bit wide fields corresponding to the clock inputs of
CLK[3:0]
various peripherals. The values written to these bit fields specify a signal
source that is an output from another peripheral. All of the possible
encodings represent sources that are clock signals (or at least could be
clock signals in some systems).
that are controlled by the Group A register,
SRU Configuration registers correspond to inputs. The value written to
the bit field specifies the signal source. This value is also an output from
some other component within the SRU.
Note that the lower portion of the patch bay in
with a large number of ports to reinforce the point that one output can be
connected to many inputs. The same encoding can be written to any num-
ber of bit fields in the same group. It is not possible to run out of patch
points for an output signal.
ADSP-2126x SHARC Processor Hardware Reference
Figure 12-11).
Figure 12-11
Digital Audio Interface
"Signal Routing Unit Regis-
diagrams the input signals
. All bit fields in the
SRU_CLK0
Figure 12-11 is shown
SRU_-
12-15