ht827a0 Holtek Semiconductor Inc., ht827a0 Datasheet - Page 22

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ht827a0

Manufacturer Part Number
ht827a0
Description
8-bit Microcontroller With Voice Rom
Manufacturer
Holtek Semiconductor Inc.
Datasheet
Tone and melody generator
The HT827A0 provides a tone frequency register
(TONE; 2AH), beat frequency register (BEAT;
28H) as well as tempo frequency register
(TEMPO; 29H) for generating melody and sound
effects.
The chip can generate four octaves, labeled
from C2
tained by first writing the related data into a
tone frequency register (TONE; 2AH) and then
enabling the tone counter. A Tone frequency is
generated and remained if the tone counter
overflows.
TN0~
TN3
OCT0
OCT1
TEN
Labels
Labels (TMRC)
¾
TE
TON
¾
TM0
TM1
¾
#
to C6. Desired frequencies can be ob-
Bits
0~3
4
5
6
7
TONE register
To define the tone frequency
(refer to the tone frequency
table)
To define the 4 octave tone
frequencies (refer to the
tone frequency table)
Unused bit, read as ²0²
To enable/disable the tone
counter
(0= disabled; 1= enabled)
Bits
0~2
3
4
5
6
7
Function
Unused bits, read as ²0²
To define the TMR active edge of a timer/event counter
(0=active on low to high; 1=active on high to low)
To enable/disable timer counting (0=disabled; 1=enabled)
Unused bits, read as ²0²
To define the operation mode
01=Event count mode (external clock)
10=Timer mode (internal clock)
11=Pulse width measurement mode
00=Unused
TMRC register
22
The BEAT register counts melody beats. Bit 7
(BTO) of the BEAT register is set when the beat
counter overflows. No interrupt is generated if
the beat counter overflows. So bit 7 (BTO) of the
BEAT register must be polled to generate correct
beat frequencies. After reading the BTO status,
the bit 7 should be cleared by the programmer to
avoid malfunction of the next polling.
Labels Bits
B0~B6
BTO
Function
0~6
7
BEAT register
To define the beat frequency
(refer to the beat frequency
table)
BTO is set during beat
counter time-out
TONE counter
Function
March 15, 2000
HT827A0

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