HT46RU25 Holtek Semiconductor Inc., HT46RU25 Datasheet - Page 24

• Manufacturer Part Number: HT46RU25
• Description: Ht46ru25/ht46cu25 -- A/d Type 8-bit Mcu
• Manufacturer: Holtek Semiconductor Inc.

A/D Converter
The 8 channels and 12-bit resolution A/D converter are
implemented in this microcontroller. The reference volt-
age is VDD. The A/D converter contains 4 special regis-
ters which are; ADRL (24H), ADRH (25H), ADCR (26H)
and ACSR (27H). The ADRH and ADRL are A/D result
register higher-order byte and lower-order byte and are
read-only. After the A/D conversion is completed, the
ADRH and ADRL should be read to get the conversion
result data. The ADCR is an A/D converter control regis-
ter, which defines the A/D channel number, analog
channel select, start A/D conversion control bit and the
end of A/D conversion 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 falling edge (0 1 0). At the end of A/D con-
version, the EOCB bit is cleared. The ACSR is A/D clock
setting register, which is used to select the A/D clock
source.
The A/D converter control register is used to control the
Rev. 1.30
(6+2) PWM Mode
(7+1) PWM Mode
24
A/D converter. The bit2~bit0 of the ADCR are used to
select an analog input channel. There are a total of eight
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
pull-high resistor of this I/O line are disabled and the A/D
converter circuit is powered 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 the
A/D converter. Giving START bit a rising edge and fall-
ing edge means that the A/D conversion has started. In
order to ensure the A/D conversion is completed, the
START should remain at 0 until the EOCB is cleared to
Bit 7 of the ACSR register is used for test purposes only
and must not be used for other purposes by the applica-
tion program. Bit1 and bit0 of the ACSR register are
used to select the A/D clock source.
0 (end of A/D conversion).
HT46RU25/HT46CU25
March 9, 2007