Media Technology Systems ION8.8 User Manual
Page 12
Page 12 of 26
Jul‐09
Sine wave
2*F/Sample Rate
Freq
OID value 2^31
20
1789570
100
8947849
500
44739243
1000
89478485
10000
894784853
20000
1789569707
Figure 3-6: Frequency OID values
While the sign (sg) and fraction bits (fb) attributes give some indication of how the DSP
might
interpret
the
values
(as
shown
in
the
examples
above),
it
is
the
specifics
of
the
DSP
implementation
that
determine
exactly
how
values
are
interpreted.
The
full
suite
of
crunch
values
are
found
in
the
DSP
Conductor
folder
shown
below.
DSP
conductor
can
be
downloaded
from
the
Cirrus
Logic
website.
C:\Program
Files\Cirrus
Logic\DSPConductor\plugins\coyote\devices
The
“imp”
xml
file
contains
details
of
the
crunch
functions.
These
can
be
opened
in
the
xml
editor
embedded
in
Internet
Explorer.
For
example
the
crunch
functions
for
a
sine
wave
generator
are
found
in
the
file
“generator_sine_wave.imp.xml”.
The
file
contains
the
text
for
a
crunch
function
written
in
python,
as
shown
below…
scale_factor
=
float(
property[
"scale_factor"
]
)
sample_rate
=
float(
property[
"sample_rate"
]
)
*
scale_factor
block_size
=
float(
property[
"block_size"
]
)
*
scale_factor
ramp_time_constant
=
float(
property[
"ramp_time_constant"
]
)
block_rate
=
sample_rate
/
block_size
ramp
=
1
‐
math.exp(
‐1
/
(
ramp_time_constant
*
block_rate
)
)
omega
=
2
*
frequency
/
sample_rate;
gain
=
‐math.pow(
10,
(
level
‐
20
)
/
20
)
/
16
if
mute
:
gain
=
0
The
crunch
function
can
easily
be
converted
to
C#
or
C++
code
for
use
in
other
applications.
3.5 OID List for the ION2.0 and ION0.2
The
MTS_AMP.xml
file
on
the
CDROM
has
a
complete
list
of
all
the
OID’s
and
offsets
for
the
amplifier
read/write
and
red
only
values,
where
the
devices
relate
to
the
schematic
in
Figure 2-1.