參數(shù)資料
型號: PCD3350A
廠商: NXP Semiconductors N.V.
英文描述: 8-bit microcontroller with DTMF generator, 256 bytes EEPROM and real-time clock
中文描述: 8位雙音多頻發(fā)電機,256字節(jié)EEPROM和實時時鐘控制器
文件頁數(shù): 9/36頁
文件大?。?/td> 204K
代理商: PCD3350A
1996 Dec 18
9
Philips Semiconductors
Product specification
8-bit microcontroller with DTMF generator,
256 bytes EEPROM and real-time clock
PCD3350A
If EDCO = 1 and DIV3 = 1 in the MDYCON register: a
square wave with the frequency f
DTMF
=
1
3
×
f
xtal
is output
on the derivative port line DP1.7/DCO. If EDCO = 1 and
DIV3 = 0: a square wave with the frequency f
DTMF
= f
xtal
is
output on the derivative port line DP1.7/DCO.
The melody output drive depends on the configuration of
port P1.7/MDY, see Chapter 14, Table 27.
6.4
Frequency registers
The two frequency registers HGF and LGF define two
frequencies. From these, the digital sine synthesizers
together with the Digital-to-Analog Converters (DACs)
construct two sine waves. Their amplitudes are precisely
scaled according to the bandgap voltage reference. This
ensures tone output levels independent of supply voltage
and temperature. The amplitude of the Low Group
Frequency sine wave is attenuated by 2 dB compared to
the amplitude of the High Group Frequency sine wave.
The two sine waves are summed and then filtered by an
on-chip switched capacitor and RC low-pass filters.
These guarantee that all DTMF tones generated fulfil the
CEPT recommendations with respect to amplitude,
frequency deviation, total harmonic distortion and
suppression of unwanted frequency components.
The value 00H in a frequency register stops the
corresponding digital sine synthesizer. If both frequency
registers contain 00H, the whole frequency generator is
shut off, resulting in lower power consumption.
The frequency ‘f’ of the sine wave generated from either of
the frequency registers is a function of the clock frequency
‘f
xtal
’ and the decimal value ‘x’ held in the register.
The equation relating these variables is:
; where 60
x
255.
The frequency limitation given by x
60 is due to the
low-pass filters which would attenuate higher frequency
sine waves.
6.5
DTMF frequencies
Assuming an oscillator frequency f
xtal
= 3.58 MHz, the
DTMF standard frequencies can be implemented as
shown in Table 5.
f
f
23 x
2
+
)
[
]
---------------------------------
=
The relationships between telephone keyboard symbols,
DTMF frequency pairs and the frequency register contents
are given in Table 6.
Table 5
DTMF standard frequencies and their
implementation; value = LGF, HGF contents
Table 6
Dialling symbols, corresponding DTMF
frequency pairs and frequency register contents
VALUE
(HEX)
FREQUENCY (Hz)
DEVIATION
STANDARD
GENERATED
(%)
(Hz)
DD
C8
B5
A3
7F
72
67
5D
697
770
852
941
1209
1336
1477
1633
697.90
770.46
850.45
943.23
1206.45
1341.66
1482.21
1638.24
0.13
0.06
0.18
0.24
0.21
0.42
0.35
0.32
0.90
0.46
1.55
2.23
2.55
5.66
5.21
5.24
TELEPHONE
KEYBOARD
SYMBOLS
DTMF FREQ.
PAIRS
(Hz)
LGF
VALUE
(HEX)
HGF
VALUE
(HEX)
0
1
2
3
4
5
6
7
8
9
A
B
C
D
#
(941, 1336)
(697, 1209)
(697, 1336)
(697, 1477)
(770, 1209)
(770, 1336)
(770, 1477)
(852, 1209)
(852, 1336)
(852, 1477)
(697, 1633)
(770, 1633)
(852, 1633)
(941, 1633)
(941, 1209)
(941, 1477)
A3
DD
DD
DD
C8
C8
C8
B5
B5
B5
DD
C8
B5
A3
A3
A3
72
7F
72
67
7F
72
67
7F
72
67
5D
5D
5D
5D
7F
67
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