EM78P568

8-bit OTP Micro-controller

__________________________________________________________________________________________________________________________________________________________________

* This specification are subject to be changed without notice.

45

01/31/2004

V4.7

Description for register control bits

ASW1 ~ ASW4 for analog input/output signal path switching

RXPWR for power control of receiving RX AMP and ZC

TXPWR for power control of transmitting MIC AMP and Summing AMP

AMUTE for MIC AMP output signal muting

P65S for receiving audio output pin AURX or port P65 pin switching

P66S for transmitting output pin MTX or port P66 pin switching

The following is the above CTCSS block signal flow and it is easy to use these figures to explain how CTCSS

works. (‘blue’ highlight means signal flow and switch setting)

(1) RX : receiving CTCSS tone

Audio

BPF

VRF

VRF

Rx AMP

MIC AMP

Z C

AURX/P65

RXO

RXI

MICI

MICO

Summing

MTX/P66

VRF

-10dB

0dB

ASW1

ASW2

RXPWR = 1

LPFPWR = 1

BPFPWR

Sub-Audio

LPF

ASW4 = 0

MUX

PORT66

MTX

MUX

PORT65

AURX

P65S

P66S

AMP

MUX

ASW3 = 0

MUX

MUX

MUX

DETO

TXPWR

TXPWR

RXPWR =1

VRX1

VTX1

VRX2

VTX2

VRX3

VTX3

VRX4

VTX4

(from DAC output buffer B2)

CTCSS tone input

MUX

MICO

AMUTE

Fig.18

(2) RX : receiving audio

Audio

BPF

VRF

VRF

Rx AMP

MIC AMP

Z C

AURX/P65

RXO

RXI

MICI

MICO

Summing

MTX/P66

VRF

-10dB

0dB

ASW1 = 0

ASW2 = 0

RXPWR

LPFPWR

BPFPWR = 1

Sub-Audio

LPF

ASW4

MUX

PORT66

MTX

MUX

PORT65

AURX

P65S = 1

P66S

AMP

MUX

ASW3

MUX

MUX

MUX

DETO

TXPWR

TXPWR

VRX1

VTX1

VRX2

VTX2

VRX3

VTX3

VRX4

VTX4

(from DAC output buffer B2)

CTCSS tone input

MUX

MICO

AMUTE

RXPWR =1

Fig.19