mpc82x52a Megawin Technology, mpc82x52a Datasheet - Page 54

• Manufacturer Part Number: mpc82x52a
• Description: 8-bit Micro-controller
• Manufacturer: Megawin Technology

Analog to Digital Converter
54
The ADC on MPC82x52A is an 8-bit resolution, successive-approximation approach, and
medium-speed A/D converter. V
internal voltage-scaling DAC use, and the typical sink current on it is 600uA ~ 1mA. For
MPC82x52A, these two references are internally tied to VDD and GND, separately.
Conversion is invoked since ADCS bit is set. Prior to ADC conversion, the desired I/O ports for
analog inputs should be configured as input-only or open-drain mode first. The conversion
takes around a fourth cycles to sample analog input data and other three fourths cycles in
successive-approximation steps. Total conversion time is controlled by two register bits –
SPEED1 and SPEED0. Analog input source comes from P1, and one of the eight-channels is
multiplexed by analog multiplexer into the comparator. When conversion is completed, the
result will be saved onto ADCV register. After the result has been loaded onto ADCV register,
ADCI will be set. ADCI associated with its enable register AUXR.4 (EADCI), shares ESPI bit
with SPI block to control the interrupt. ADCI should be cleared in software. The ADC interrupt
service routine vectors to 2B
power of ADC is turned off by hardware.
P1.7(AIN7)
P1.6(AIN6)
P1.5(AIN5)
P1.4(AIN4)
P1.3(AIN3)
P1.2(AIN2)
P1.1(AIN1)
P1.0(AIN0)
8-bit DAC
ADCV = 256 x
H
. When the chip enters idle mode or power-down mode, the
REFP
MPC82x52A Data Sheet
+
-
Comparator
8
/ V
REFM
ADCON
V
Vin – V
REFP
SPEED1 SPEED0
is the positive/negative reference voltage input for
- V
REFM
Approximation
REFM
ADCI ADCS
Successive
ADCTL Register
Regiter
CHS2 CHS1 CHS0
B7
B6
B5
ADCV Register
B4
B3
B2
MEGAWIN
B1
B0