HT46R064D/065D/066D
Enhanced A/D Type 8-Bit OTP MCU with LED Driver
A/D Converter Data Registers - ADRL, ADRH
The device, which has an internal 12-bit A/D converter, requires two data registers, a high byte
register, known as ADRH, and a low byte register, known as ADRL. After the conversion process
takes place, these registers can be directly read by the microcontroller to obtain the digitised
conversion value. Only the high byte register, ADRH, utilises its full 8-bit contents. The low byte
register utilises only 4 bit of its 8-bit contents as it contains only the lowest bits of the 12-bit converted
value.
In the following table, D0~D11 is the A/D conversion data result bits.
Register
ADRL
Bit7
D3
Bit6
D2
Bit5
D1
Bit4
D0
Bit3
¾
Bit2
¾
Bit1
¾
Bit0
¾
ADRH
D11
D10
D9
D8
D7
D6
D5
D4
A/D Data Registers
ADRH, ADRL Register
ADRH
ADRL
Bit
7
6
5
4
3
D7
R
2
1
D5
R
0
D4
R
7
D3
R
6
D2
R
5
4
D0
R
3
2
1
0
Name D11 D10 D9
D8
R
D6
R
D1
R
¾
¾
¾
¾
¾
¾
¾
¾
¾
¾
¾
¾
R/W
R
x
R
x
R
x
POR
x
x
x
x
x
x
x
x
x
²x² unknown
unimplemented, read as ²0²
D11~D0: ADC conversion data
A/D Converter Control Registers - ADCR, ACSR
To control the function and operation of the A/D converter, two control registers known as ADCR and
ACSR are provided. These 8-bit registers define functions such as the selection of which analog
channel is connected to the internal A/D converter, which pins are used as analog inputs and which are
used as normal I/Os, the A/D clock source as well as controlling the start function and monitoring the
A/D converter end of conversion status.
The ACS2~ACS0 bits in the ADCR register define the channel number. As the device contains only
one actual analog to digital converter circuit, each of the individual 8 analog inputs must be routed to
the converter. It is the function of the ACS2~ACS0 bits in the ADCR register to determine which
analog channel is actually connected to the internal A/D converter.
The PCR control register also contains the PCR7~PCR0 bits which determine which pins on PA0~PA2,
PA5, PB0~PB3 are used as analog inputs for the A/D converter and which pins are to be used as normal
I/O pins.
The START bit in the 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 ADCR
register will be set to a ²1² 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.
Rev. 1.00
58
January 12, 2011
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
