HT46C47 Holtek Semiconductor, HT46C47 Datasheet - Page 18

• Manufacturer Part Number: HT46C47
• Description: (HT46C46 / HT46C47) Cost-Effective A/D Type 8-Bit MCU
• Manufacturer: Holtek Semiconductor

A/D Converter
The 4 channels and 8-bit resolution for the HT46R46/
HT46C46 or 9-bit resolution for the HT46R47/HT46C47
A/D converter are implemented in this microcontroller.
The reference voltage is VDD. The A/D converter con-
tains 3 special registers for the HT46R46/HT46C46
which are; ADR (21H), ADCR (22H) and ACSR (23H) or
contains 4 special registers for the HT46R47/HT46C47
whice are; ADRL (20H), ADRH (21H), ADCR (22H) and
ACSR (23H). The ADR is HT46R46/ HT46C46 an A/D
result register that is read-only. The ADRH and ADRL
are HT46R47/HT46C47 A/D result register higher-order
byte and lower-order byte which are read-only. After the
A/D conversion is completed, the ADR (HT46R46/
HT46C46) or ADRL, ADRH (HT46R47/HT46C47)
should be read to get the conversion result data. The
ADCR is an A/D converter control register, which de-
fines the A/D channel number, analog channel select,
start A/D conversion control bit and the end of A/D con-
version flag. If the users want to start an A/D conversion,
define PB configuration, select the converted analog
channel, and give START bit a raising edge and a falling
edge (0 1 0). At the end of A/D conversion, the
EOCB bit is cleared and an A/D converter interrupt oc-
curs (if the A/D converter interrupt is enabled). The
ACSR is A/D clock setting register, which is used to se-
lect the A/D clock source.
The A/D converter control register is used to control the
A/D converter. The bit2~bit0 of the ADCR are used to
select an analog input channel. There are a total of four
channels to select. The bit5~bit3 of the ADCR are used
to set PB configurations. PB can be an analog input or
as digital I/O line decided by these 3 bits. Once a PB line
is selected as an analog input, the I/O functions and
Rev. 1.00
HT46R46/HT46C46/HT46R47/HT46C47
PWM
18
pull-high resistor of this I/O line are disabled, and the
A/D converter circuit is power on. The EOCB bit (bit6 of
the ADCR) is end of A/D conversion flag. Check this bit
to know when A/D conversion is completed. The START
bit of the ADCR is used to begin the conversion of A/D
converter. Give START bit a raising edge and falling
edge that means the A/D conversion has started. In or-
der to ensure the A/D conversion is completed, the
START should stay at 0 until the EOCB is cleared to
The bit 7 of the ACSR is used for testing purpose only. It
can not be used for the users. The bit1 and bit0 of the
ACSR are used to select A/D clock sources.
When the A/D conversion is completed, the A/D inter-
rupt request flag is set. The EOCB bit is set to 1 when
the START bit is set from 0 to 1 .
Note:
Note:
ADRL (20H), ADRH (21H) Register for HT46R47/HT46C47
0 (end of A/D conversion).
Register Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Register Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
ADRH
ADRL
ADR
ADR (21H) Register for HT46R46/HT46C46
D0~D7 is A/D conversion result data bit
LSB~MSB.
D0~D8 is A/D conversion result data bit
LSB~MSB.
D7
D0
D8
D6
D7
D5
D6
D4
D5
D3
D4
December 28, 2004
D2
D3
D1
D2
D0
D1