HT83XXX

Rev. 0.10

18

August 25, 2003

Preliminary

Audio Output

- PWMD (28H)

The HT83XXX provides one 8-bit PWM interface for driving an external 8

W speaker. The programmer must write the

voice data to register PWMD (28H)

Pulse Width Modulation Control Register

- PWMCR (26H)

Bit 7

Bit 6 (R/W)

Bit 5 (R/W)

Bit 4

Bit 3 (R/W)

Bit 2 (R/W)

Bit 1

Bit 0 (R/W)

¾

P1

P0

¾

Single_PWM

VROMC

¾

PWMC

S y s t e m c l o c k

P r e s c a l e r

P W M D a t a

B u f f e r ( 2 8 H )

7 B i t s C o u n t e r

( B i t 6 ~ B i t 0 )

D a t a B u s

O v e r f l o w

P W M D A C 1 f o r S P E A K E R

F 0

S t a r t b i t

2 6 H . 0

D i v .

P W M I

F 2

C K

P E

D

C K

R

F 1

Q

Q

P W M D A C 2 f o r S P E A K E R

B i t 7 ( s i g n b i t )

PWM

PWMC: Start bit of PWM output

After waiting one cycle end , stop the PWM counter and

keep in low signal

VROMC: Enable voice ROM power circuit (1=enable;

0=disable)

Single_PWM: Driving PWM signal only by PWM1 port.

(1=enable; 0=disable)

The HT83xxx provides an 8-bit (bit 7 is a sign bit, if Sin-

gle_PWM = 0) PWM interface. The PWM provides two

pad outputs: PWM1, PWM2 which can directly drive a

piezo or a 8

W speaker without adding any external ele-

ment (green mode), or using only port PWM1 (Set Sin-

gle_PWM = 1) to drive piezo or a 8

W speaker with

external element.

When Setting Single_PWM = 1, choose voice

data7~data1 as the output data (no sign bit on it).

Setting data to P0 and P1 can generate various sam-

pling rates (5kHz/6kHz/8kHz):

P1 P0

Sampling

Rate

Carrier

frequency

Preload

Times

PWM Code

Range

0

0

5kHz

30kHz

6

1~127

0

1

6kHz

30kHz

5

1~127

1

0

8kHz

32kHz

4

1~124

¾¾

XX

X

X

If the sign bit is 0, then the signal is output to PWM1and

the PWM2 will get a GND level voltage after setting start

bit to 1. If the sign bit is 1, then the signal is output to

PWM2 and the PWM1 will get a GND level voltage after

setting start bit to 1.

PWM ½ output Initial low level , and stop in low level

If PWMC from low to high then start PWM output and

5kHz/6kHz/8kHz latch new data , if no update then keep

the old value.

If PWMC from high to low, in duty end, stop PWM output

and stop the counter.

Voice ROM Data Address Latch Counter

The voice ROM data address latch counter is the hand-

shaking between the microcontroller and voice ROM,

where the voice codes are stored. One 8-bit of voice

ROM data will be addressed by setting 18-bit address

latch counter LATCH0H/LATCH0M/LATCH0L. After the

8-bit voice ROM data is addressed, a few instruction cy-

cles (4

ms at least) will be generated to latch the voice

ROM data, then the microcontroller can read the voice

data from LATCHD (2AH).

Example: Read an 8-bit voice ROM data which is lo-

cated at address 000007H by address latch 0

set

[26H].2

; Enable voice ROM circuit

mov

A, 07H

;

mov

LATCH0L, A ; Set LATCH0L to 07H

mov

A, 00H

;

mov

LATCH0M, A ; Set LATCH0M to 00H

mov

A, 00H

;

mov

LATCH0H, A ; Set LATCH0H to 00H

call

Delay Time

; Delay a short period of time

mov

A, LATCHD

; Get voice data at 000007H