EM78P568

8-bit OTP Micro-controller

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* This specification are subject to be changed without notice.

50

01/31/2004

V4.7

VII.13 Programming tone generators

N-R

resistor

string

Tone 1

analog

multiplexer

Tone 2

analog

multiplexer

Tone 2

programmable counter

Tone 1

programmable counter

TONE

Buffer

Buffer

Mixer

fi

fs2

T2Mux

control

T1Mux

control

fs1

(output inverse)

Vref2

Vref2

Vref2

Reference

voltage

Vref1

Vref1

Vref2

VT

fs1 = fi / N1,

fs2 = fi / N2

N2

N1

fT1 = fi / N1 / N,

tone1 output frequency

fT2 = fi / N2 / N,

tone2 output frequency

T27 ~ T20

T1A ~ T10

Name

Register bit location

T1A ~ T18 IOCE PAGE0 bit 2 ~ 0

T17 ~ T10

IOCD PAGE0 bit 7 ~ 0

T27 ~ T20

IOCA PAGE0 bit 7 ~ 0

Fig.23 Programming tone generator

Programming tone generators is an universal dual tone generators. It includes Tone 1 and Tone 2 generators which

can be combines as dual tones output or either one tone output. The clock source fi is come from PLL and divided

to required ratio. Tone 1 and Tone 2 are sinewave output. The programming tone generators consists of Tone 1/2

programmable counters, analog multiplexer, N-R resistor string, output buffers, mixer amplifier and reference

voltage. N-R resistor is a voltage divider which has different output levels. By programmable counters and analog

multiplexer, the hardware will automatically generate individual divider output with circular order back and forth.

The output frequency will be 119957/N1 for Tone 1 and 11.957/N2 for Tone 2, where N1 is 11-bit T1A ~ T10 and

N2 is 8-bit T17 ~ T10.