s3c72m9 Samsung Semiconductor, Inc., s3c72m9 Datasheet - Page 348

• Manufacturer Part Number: s3c72m9
• Description: The S3c72m5/s3c72m7/s3c72m9 Single-chip Cmos Microcontroller Has Been Designed For High Performance Using Samsung S
• Manufacturer: Samsung Semiconductor, Inc.

COMPARATOR
PORT 4 MODE REGISTER (P4MOD)
P4MOD register settings determine if P4.0 P4.1 and P4.2 are used for analog or digital input. The P4MOD register is
4-bit write-only register. P4MOD is mapped to address FCEH. A reset operation initializes all P4MOD register
values to zero, configuring P4.0 P4.1 and P4.2 as a digital input port.
When a P4MOD bit is set to "0", the corresponding pin is configured as a digital input pin. When set to "1", it is
configured as an analog input pin: P4MOD.0 for P4.0, P4MOD.1 for P4.1, and P4MOD.2 for P4.2.
COMPARATOR OPERATION
The comparator compares analog voltage input at CIN0–CIN2 with an external or internal reference voltage (V
that is selected by the CMOD register. The result is written to the comparison result register CMPREG at address
FD4H. The comparison result at internal reference is calculated as follows:
To obtain a comparison result, the data must be read out from the CMPREG register after V
changing the CMOD value after a conversion time has elapsed.
14-4
FCEH
(CMPCLK, fx/16, fx/128)
If "1" Analog input voltage
If "0" Analog input voltage
Result (CMPREG)
Comparator Clock
Voltage (CIN0-2)
Voltage (V
Analog Input
Comparison
"0"
Reference
REF
P4MOD.2
)
Comparison
Start
V
V
REF
REF
P4MOD.1
Figure 14-3. Conversion Characteristics
+ 150 mV
– 150 mV
Comparsion Time
(CMPCLK x 8)
Unkwon
P4MOD.0
Comparison
End
1
S3C72M5/C72M7/C72M9/P72M9 (Preliminary Spec)
1
Unkwon
REF
is updated by
0
REF
)