GMS84512 Datasheet, PDF (51/123 Pages) Hynix Semiconductor – 8-BIT SINGLE CHIP MICROCOMPUTER

GMS 84512 / 84524
3.4 A/D COMPARATOR
A/D comparator has an 5-bit resolution, and input is possible up to 4 channel. A/D comparator
is consisted of analog input multiplexer, 5-bit D/A conversion circuit, sample & holder and control
circuit
FIG.3.4.1 is a block diagram of A/D comparator
Data BUS
CIS
2
10
5
CMR
ADCM ADCM ADCM ADCM ADCM _-
0
1
2
3
4
6
7
COR ADEN
5
RESISTER LADDER
5-bit D/A C.
Cin0
Cin1
Cin2
Cin3
2
ANALOG
INPUT
MULTIPLEXER
ADEN
Vref
-
+
COMPARATOR
OUTPUT
LATCH
FIG. 3.4.1 Block Diagram of A/D Comparator
3.4.1 A/D COMPARATOR
Following produce is used.
- Write CIS register to select analog input channel.
- After writing CMR(ADCM0~4) to select reference voltage, set ADEN(bit7 of CMR) to “1” to
start A/D comparision..
< Notice > CMRcan’t be used with Bit Manipulation instruction and setting the reference
voltage and starting A/D comparision can be used at same time..
- A/D Comparision processing needs 16machine cycle(8us)
- The result of comparision is stored in COR(bit6 of CMR).
That is, if <input voltage > reference voltage>, COR=1
if <input voltage < reference voltage>, COR=0
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