SI3216PPQ1-EVB Silicon Laboratories Inc, SI3216PPQ1-EVB Datasheet - Page 37

• Manufacturer Part Number: SI3216PPQ1-EVB
• Description: BOARD EVAL W/SI3201 INTERFACE
• Manufacturer: Silicon Laboratories Inc
• Series: ProSLIC®r

Specifications of SI3216PPQ1-EVB

• Main Purpose: Interface, Analog Front End (AFE)
• Utilized Ic / Part: Si3216
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

2.3.2. Oscillator Frequency and Amplitude
Each of the two-tone generators contains a two-pole
resonant
frequency and amplitude. These two-tone generators
are programmed via indirect registers OSC1, OSC1X,
OSC1Y, OSC2, OSC2X, and OSC2Y. The sample rate
for the two oscillators is 16 kHz. The equations are as
follows:
where f
where desired V
n = 1 or 2 for oscillator 1 or oscillator 2, respectively.
For example, to generate a DTMF digit of 8, the two
required tones are 852 Hz and 1336 Hz. Assuming the
generation of half-scale values (ignoring twist) is
desired, the following values are calculated:
The above computed values are written to the
corresponding registers to initialize the oscillators. Once
the oscillators are initialized, the oscillator control
registers can be accessed to enable the oscillators and
direct their outputs.
OSC1X
OSC2X
OSCnX
n
OSC2 = 0.86550 (2
OSC1
=
is the frequency to be generated;
=
=
1
-- -
4
oscillator
1
-- -
4
coeff
coeff
1
-- -
4



coeff
=
-------------------- -
1.94455
rms
.05545
0.13450
-------------------- -
1.86550
OSCn = coeff
2
1
1 coeff
----------------------- -
1
0.94455 2
=
+
–
=
n
is the amplitude to be generated;
coeff
cos
= cos(2  f
cos
OSCnY = 0,
OSC1Y = 0
OSC2Y = 0
circuit







21336
------------------- -

2852
---------------- -
16000
16000
2


15
15
15
2

15
2
) = 28361 = 6EC8h

–
15
n
=
–
with
n
1


x (2
/16 kHz),
–


 0.5
1
30951

1
=
 0.5
=


15
0.94455

0.86550
a
);
Desired V
------------------------------------ -
=
=
1.11 V
=
78E6h
692
programmable
1098
=
rms
2B3h
=
rms
44Bh
Rev. 1.0
2.3.3. Tone Generator Cadence Programming
Each of the two-tone generators contains two timers,
one for setting the active period and one for setting the
inactive period. The oscillator signal is generated during
the active period and suspended during the inactive
period. Both the active and inactive periods can be
programmed from 0 to 8 seconds in 125 µs steps. The
active period time interval is set using OAT1 (direct
registers 36 and 37) for tone generator 1 and OAT2
(direct registers 40 and 41) for tone generator 2.
To enable automatic cadence for tone generator 1,
define the OAT1 and OIT1 registers and then set the
O1TAE bit (direct Register 32, bit 4) and O1TIE bit
(direct Register 32, bit 3). This enables each of the
timers to control the state of the Oscillator Enable bit,
O1E (direct Register 32, bit 2). The 16-bit counter
begins counting until the active timer expires, at which
time the 16-bit counter resets to zero and begins
counting until the inactive timer expires. The cadence
continues until the user clears the O1TAE and O1TIE
control bits. The zero crossing detect feature can be
implemented by setting the OZ1 bit (direct Register 32,
bit 5). This ensures that each oscillator pulse ends
without a dc component. The timing diagram in
Figure 21 is an example of an output cadence using the
zero crossing feature.
One-shot oscillation can be achieved by enabling O1E
and O1TAE. Direct control over the cadence can be
achieved by controlling the O1E bit (direct Register 32,
bit 2) directly if O1TAE and O1TIE are disabled.
The operation of tone generator 2 is identical to that of
tone generator 1 using its respective control registers.
Note: Tone Generator 2 should not be enabled simultane-
Continuous
waveforms may be created using tone generator 1 (not
available on tone generator 2) by setting the REL bit
(direct Register 32, bit 6), which enables reloading of
the OSC1, OSC1X, and OSC1Y registers at the
expiration of the active timer (OAT1).
ously with the ringing oscillator due to resource sharing
within the hardware.
phase
frequency-shift
Si3216
keying
(FSK)
37