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STW5093

tone range" (i.e. from 15.6Hz to 3984Hz in 15.6Hz step) according to the values described in CONTROL REG-

ISTER CR8 and CR9.

CONTROL REGISTER CR11

Bit BE(7) permits connection of a f1 squarewave PWM Ring signal, amplitude modulated or not by a f2 square-

wave signal, to buzzer driver output BZ. Bits BZ5 to BZ0 define the duty cycle of the PWM squarewave, accord-

ing to the following formula:

Duty Cycle = CR11(5 to 0) x 0.78125%

where CR11(5 to 0) is the decimal equivalent of the binary value BZ5 to BZ0.

When BE = 1, if bits F1 = 1 and F2 = 0 in register CR7, a f1 PWM ring signal is present at the buzzer output,

while if bits F1 = 1 and F2 = 1 in register CR7 the f1 PWM ring signal is also amplitude modulated by a f2 square-

wave frequency. Bit BI (6) allows to chose the logic level at which the duty cycle is referred: BI = 0 means that

duty cycle is intended as the relative width of the logic1, while BI = 1 means that duty cycle is intended as the

relative width of the logic 0. When BE = 0 (or during power down) BZ = 0 if BI = 0 or BZ = 1 if BI = 1.

Table 14. Examples of Usual Frequency Selection (Standard frequency tone range)

Description

f1 value (decimal)

Theoretic value (Hz)

Typical value (Hz)

Error%

Tone 250 Hz

Tone 330 Hz

Tone 425 Hz

Tone 440 Hz

Tone 800 Hz

Tone 1330 Hz

32

42

54

56

102

170

250

330

425

440

800

1330

250

328.2

421.9

437.5

796.9

1328.1

-.00

-.56

-.73

-.56

-.39

-.14

DTMF 697Hz

DTMF 770 Hz

DTMF 852 Hz

DTMF 941 Hz

DTMF 1209 Hz

DTMF 1336 Hz

DTMF 1477 Hz

DTMF 1633 Hz

89

99

109

120

155

171

189

209

697

770

852

941

1209

1336

1477

1633

695.3

773.4

851.6

937.5

1210.9

1335.9

1476.6

1632.8

-.24

+.44

-.05

-.37

+.16

-.01

.00

.00

SOL

LA

SI

DO

RE

MI flat

MI

FA

FA sharp

SOL

SOL sharp

LA

SI

DO

RE

MI

50

56

63

67

75

80

84

89

95

100

106

113

126

134

150

169

392

440

494

523.25

587.33

622.25

659.25

698.5

740

784

830.6

880

987.8

1046.5

1174.66

1318.5

390.6

437.5

492.2

523.5

586.0

625.0

656.3

695.3

742.2

781.3

828.2

882.9

984.4

1046.9

1171.9

1320.4

-.30

-.56

-.34

+.04

-.23

+.45

-.45

-.45

+.30

-.34

-.29

+.33

-.34

+.04

-.23

+.14