GMS81C2012/GMS81C2020
HYUNDAI MicroElectronics
13. ANALOG DIGITAL CONVERTER
The analog-to-digital converter (A/D) allows conversion
of an analog input signal to a corresponding 8-bit digital
value. The A/D module has eight analog inputs, which are
multiplexed into one sample and hold. The output of the
sample and hold is the input into the converter, which gen-
erates the result via successive approximation. The analog
supply voltage is connected to AVDD of ladder resistance
of A/D module.
SEL[11:8] in R7FUNC register. And selected the corre-
sponding channel to be converted by setting ADS[3:0].
How to Use A/D Converter
The processing of conversion is start when the start bit
ADST is set to "1". After one cycle, it is cleared by hard-
ware. The register ADCR contains the results of the A/D
conversion. When the conversion is completed, the result
is loaded into the ADCR, the A/D conversion status bit
ADSF is set to "1", and the A/D interrupt flag ADIF is set.
The block diagram of the A/D module is shown in Figure
13-2. The A/D status bit ADSF is set automatically when
A/D conversion is completed, cleared when A/D conver-
sion is in process. The conversion time takes maximum 20
uS (at fXI=4 MHz)
The A/D module has two registers which are the control
register ADCM and A/D result register ADR. The register
ADCM, shown in Figure 13-1, controls the operation of
the A/D converter module. The port pins can be configured
as analog inputs or digital I/O.
To use analog inputs, each port is assigned analog input
port by setting the bit ANSEL[7:0] in R6FUNC register.
Also it is assigned analog input port by setting the bit AN-
R/W R/W R/W R/W R/W
R
7
-
6
5
4
3
2
1
0
ADDRESS: 0EAH
INITIAL VALUE: -000 0001B
BTCL
ADCM
ADS3 ADS2 ADS1 ADS0
ADST ADSF
ADEN
A/D status bit
0: A/D conversion is in progress
1: A/D conversion is completed
A/D start bit
Setting this bit starts an A/D conversion.
After one cycle, bit is cleared to “0” by hardware.
Analog input channel select
0000: Channel 0 (AN0)
0001: Channel 1 (AN1)
0010: Channel 2 (AN2)
0011: Channel 3 (AN3)
0100: Channel 4 (AN4)
0101: Channel 5 (AN5)
0110: Channel 6 (AN6)
0111: Channel 7 (AN7)
1000: Channel 8 (AN8)
1001: Channel 9 (AN9)
1010: Channel 10 (AN10)
1011: Channel 11 (AN11)
A/D converter Enable bit
0: A/D converter module turn off and
current is not flow.
1: Enable A/D converter
R
6
R
R
4
R
R
2
R
1
R
0
R
7
5
3
ADDRESS: 0EBH
INITIAL VALUE: Undefined
BTCL
ADCR
A/D Conversion Data
Figure 13-1 A/D Converter Control Register
62
MAR. 2000 Ver 1.00
HYNIX [ HYNIX SEMICONDUCTOR ]
