EM78P568

8-bit OTP Micro-controller

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* This specification are subject to be changed without notice.

47

01/31/2004

V4.7

(2) The other way is still to use built-in DAC tone gen. but need some external element to attenuate

CTCSS tone on DAO/P67 pin. Program some control bit to let CTCSS output on DAO/P67 pin refer

to VII.9 (3) description). Because DAO/P67 output is stair-case waveform, we need put simple RC

LPF circuit to smooth output waveform before CTCSS attenuation circuit. Also RC LPF has some

attenuation effect. It depends on its cut-off frequency of LPF. User can design by his own way.

There are two suggestion circuits for your reference as following.

MTX/P66

DAO/P67

31

32

FM

modulator

(I/O port)

VCC

(option)

(LPF for DA sample clk)

MTX/P66

DAO/P67

32

FM

modulator

(I/O port)

(bias)

31

(LPF for DA sample clk)