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Rev. 1.21
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Rev. 1.21
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HT66F488/HT66F489
A/D Flash MCU with EEPROM
HT66F488/HT66F489
A/D Flash MCU with EEPROM
ACERL Register
Bit
7
6
5
4
3
2
1
0
�a�e
ACE�
ACE6
ACE5
ACE4
ACE3
ACE2
ACE1
ACE�
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
POR
1
1
1
1
1
1
1
1
Bit 7
ACE7
: Define PB1 is A/D input or not
0: Not A/D input
1: A/D input, AN7
Bit 6
ACE6
: Define PC6 is A/D input or not
0: Not A/D input
1: A/D input, AN6
Bit 5
ACE5
: Define PC5 is A/D input or not
0: Not A/D input
1: A/D input, AN5
Bit 4
ACE4
: Define PC4 is A/D input or not
0: Not A/D input
1: A/D input, AN4
Bit 3
ACE3
: Define PC3 is A/D input or not
0: Not A/D input
1: A/D input, AN3
Bit 2
ACE2
: Define PC0 is A/D input or not
0: Not A/D input
1: A/D input, AN2
Bit 1
ACE1
: Define PB7 is A/D input or not
0: Not A/D input
1: A/D input, AN1
Bit 0
ACE0
: Define PB6 is A/D input or not
0: Not A/D input
1: A/D input, AN0
A/D Operation
The START bit in the ADCR0 register is used to start and reset the A/D converter. When the
microcontroller sets this bit from low to high and then low again, an analog to digital conversion
cycle will be initiated. When the START bit is brought from low to high but not low again, the
EOCB bit in the ADCR0 register will be set high and the analog to digital converter will be reset.
It is the START bit that is used to control the overall start operation of the internal analog to digital
converter.
The EOCB bit in the ADCR0 register is used to indicate when the analog to digital conversion
process is complete. This bit will be automatically set to “0” by the microcontroller after a
conversion cycle has ended. In addition, the corresponding A/D interrupt request flag will be set
in the interrupt control register, and if the interrupts are enabled, an appropriate internal interrupt
signal will be generated. This A/D internal interrupt signal will direct the program flow to the
associated A/D internal interrupt address for processing. If the A/D internal interrupt is disabled,
the microcontroller can be used to poll the EOCB bit in the ADCR0 register to check whether it has
been cleared as an alternative method of detecting the end of an A/D conversion cycle.
The clock source for the A/D converter, which originates from the system clock f
SYS
, can be chosen
to be either f
SYS
or a subdivided version of f
SYS
. The division ratio value is determined by the
ADCK2~ADCK0 bits in the ADCR1 register.