FX803 Datasheet, PDF (8/17 Pages) Sanyo Semicon Device – DC-DC Converter

Controlling Protocol ......
“Read Rx Tone Frequency Register” – A/C 32 , followed by 2 bytes of Reply Data.
H
Measurement of Rx Signal Frequency (S_INPUT)
The measurement details given on Pages 10 and 11 are
for a Xtal/clock frequency (f ) of 4.032MHz, a scaling
XTAL
formula for other values of f is given at the bottom of this
XTAL
page.
The input audio signal (S ) is filtered and measured in
INPUT
the Frequency Counter over a specified “measurement
period” (9.125 ms or 18.250 ms).
When the count period of a successful decode is
complete, the Rx Tone Measurement bit in the Status
Register, and the Interrupt bit (if enabled) are set.
The Rx Tone Frequency Register will now indicate the
signal frequency (S ) in the form of 2 bytes (1 and 0) as
INPUT
illustrated in Figure 6 below.
The measuring function counts the number of complete
input cycles occurring within the measurement period and
then the number of measuring-clock cycles necessary to
make up the period.
Complete
Input
Cycle
Measurement Period
Complete
Input
Cycle
Complete
Input
Cycle
Complete
Input
Cycle
Complete Measuring
Input
Clock
Cycle Cycles
S _{FILTERED AUDIO INPUT SIGNAL} 2 x _INPUT
N
R
Fig.5 Measurement of a Mid or High Band Rx Frequency
The Integer (N) – Byte 1
A binary number representing ‘twice the number of
complete input audio cycle periods’ counted during the
specified measurement period, which is:
High Band Decode
Mid Band Decode
Extended Band Decode
= 9.125 ms = “t”
= 18.250 ms = “t”
= 9.125 ms = “t”
See the bottom of this page for “t” and “f” scaling factors
The Remainder (R) – Byte 0
A binary number representing the remainder part, R,
of 2 x Input Signal Frequency (S . ‘R = number of
INPUT)
specified measuring-clock cycles’ required to complete the
specified measurement period (See N).
The clock-cycle frequencies are:
High Band Decode
Mid Band Decode
Extended Band Decode
= 56.00 kHz = “f”
= 28.00 kHz = “f”
= 56.00 kHz = “f”
(REPLY DATA)
Byte 1
(MSB) – TRANSMITTED FIRST
15 14 13 12 11 10 9 8
“0” “0”
Integer (N)
76 5
“0” “0”
Byte 0
43
(REPLY DATA)
(LSB) – TRANSMITTED LAST
21 0
Remainder (R)
Fig.6 Format of the Rx Tone Frequency Register
f Scaling Factors
XTAL
The calculations above are for an f of 4.032MHz. The
XTAL
following formulas enable the calculation of these values
using any Xtal value. Note: f values are stated in MHz.
XTAL
“t”
scaled
“f”
scaled
8
= “t” x
= “f” x
4.032
f
XTAL
f
XTAL
4.032