ht827a0 Holtek Semiconductor Inc., ht827a0 Datasheet - Page 17

• Manufacturer Part Number: ht827a0
• Description: 8-bit Microcontroller With Voice Rom
• Manufacturer: Holtek Semiconductor Inc.

The chip reset status are shown below:
Audio output and volume control
The HT827A0 provides a current type D/A out-
put for driving external 8W speaker through an
external NPN transistor. The user must write
the voice data to the register DAL (20H) and
DAH (21H). Only 12 bits which include the high
nibble of DAL and the whole byte of DAH are
used. For the current type D/A output the high
nibble data of DAL must be written at first, and
then the DAH data is written.
There are 16 steps of volume controllable level
that are provided for the current type D/A out-
put. The user only writes the volume control
data to the VCR register (22H). Only the high
nibble of VCR are used. Note that writing 0H to
the high nibble of VCR doesn¢t denote mute out-
put. When bit 7 (SRON) of the TEMPO register
(29H) is set as ²1² the change of volume level is
valid. The following is a table of the 16 kinds of
volume level:
PC
Interrupt
Prescaler
WDT
Timer/Event Counter Off
Input/Output Ports
SP
Reset circuit
0000H
Disabled
Cleared
Cleared. After a
master reset, WDT
begins counting.
Input mode
Point to the top of
the stack.
17
Note: ²xx² means don¢t care
0000 xxxx
0001 xxxx
0010 xxxx
0011 xxxx
0100 xxxx
0101 xxxx
0110 xxxx
0111 xxxx
Code
Volume
Volume level table
1/16
2/16
3/16
4/16
5/16
6/16
7/16
8/16
1000 xxxx
1001 xxxx
1010 xxxx
1011 xxxx
1100 xxxx
1101 xxxx
1110 xxxx
1111 xxxx
Code
March 15, 2000
HT827A0
Volume
9/16
10/16
11/16
12/16
13/16
14/16
15/16
16/16