Function Description

Mode selection

PB3=1, PA7=0: Key control mode

PB3=1, PA7=1: MCU control mode

PB3=0: Manual control mode

Low voltage detect

PA5=0 (normal); PA5=1 (low voltage active, program stop)

Key Control Mode

PA0: Ring Detect

When an incoming 13Hz~90Hz ring signal is detected after a period of 200ms, the

music will automatically start playing. When the incoming ring signal stops, after a pe-

riod of 6 seconds the music will stop playing.

PA1: Hook Detect

This line detects the on/off hook condition of the telephone. Only when the telephone

is in an on-hook condition, can the music be chosen and played. If the handset is

lifted to talk, the music will stop playing and the HOLD key will be effective.

PA2: Melody select key

This key chooses and plays one of the 36 stored musical melodies. When the key is

pressed the next melody in the list will be selected and played. When the HOLD key

is pressed, the telephone hold function will be activated and when an incoming ring

signal is detected the music will be played.

PA3: Telephone Hold key

If this key is pressed during a phone conversation the phone will be put on hold and

the caller can listen to the music while waiting. If, when the music is playing, the hand-

set is lifted, the music will immediately stop playing. After this happens the HOLD

function will have no effect for a period of 2 seconds.

PA4: Volume key

Controls the music volume in 8 discrete steps. Each time the key is pressed the vol-

ume will reduce one step at a time until the lowest volume is reached. When the low-

est volume is reached, the next key press will return the volume to its maximum level.

MCU Mode

PA0: clock pin

Clock from external CPU

PA1: data pin

Data from external CPU

Timing Chart

Note:

50ms after power up, the device will be ready to communicate with the external CPU using the CLK and DATA

lines.

Communication via the CLK and DATA lines is conducted in a simple manner. The device will obtain its data on

the high going edge of the CLK line. If the device does not receive a complete byte within 50ms then the pres-

ent byte will be discarded and the next byte will then be received.

Even-parity is used for data checking. For the previous 8-bits, if the total number of

²1s² is odd then the parity

bit is set to

²1², otherwise it is set to ²0². If the parity is incorrect then the byte will be discarded.

Data Type (Command)

00H~23H

This command will select and play one of the 36 stored musical melodies (play once).

30H~53H

This command will select and play one of the 36 stored musical melodies (repeatedly once).

5FH

Stop play

60H~6FH

16 level volume control, 60H refers to highest volume (power on default 60H)

HT3834

Rev. 1.00

4

November 2, 2006

C L K

D A T A

3 0 m s

B i t 0

B i t 1

B i t 2

B i t 3

B i t 4

B i t 5

B i t 6

B i t 7

P a r i t y

4 m s

T 1

T 2

T 2