S1C62740 TECHNICAL HARDWARE
EPSON
I-83
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (A/D Converter)
In this mode, the A/D converter measures the resistance value by
connecting elements as the follows:
1. Connects measured resistance such as a thermistor or other
elements between AI2 and GND terminals or between AI3 and
GND terminals
2. Connects a reference resistance where resistance value does not
change due to such factors as the temperature between AI4 and
AI2 terminals or between AI4 and AI3 terminals
3. Connects a resistance for stabilizing the AI4 output voltage
between AI4 and GND terminals.
However, it is unnecessary to connect the resistance for
stabilization when the reference resistance is 10 k
or less.
Fig. 4.12.6
Resistance measurement
Table 4.12.1 shows the analog input terminals to be used and
measurement items and it specifies them by combinations of
registers AI0–AI4 and registers AIS0–AIS3.
Table 4.12.1 Specification of the analog input terminal and measurement items
AIS3 AIS2 AIS1 AIS0
AI4
AI3
AI2
AI1
AI0
Measurement items
00000
0
01
AI0 voltage measurement (GND reference)
00000
0
10
AI1 voltage measurement (GND reference)
00000
0
1
00
AI2 voltage measurement (GND reference)
00000
1
0
00
AI3 voltage measurement (GND reference)
00001
0
00
AI4 voltage measurement (GND reference)
00010
0
11
AI1 differential voltage measurement (AI0 reference)
00100
1
00
AI3 differential voltage measurement (AI2 reference)
01001
0
1
00
AI2 resistance measurement (AI4 reference)
10001
1
0
00
AI3 resistance measurement (AI4 reference)
Note:
You should not use settings other than those in Table 4.12.1.
When measuring load (+ voltage) on the VDD side using a GND
reference for voltage measurement and differential voltage meas-
urement, you must set the load drive capacity of the middle electric
potential generation circuit matched to that load.
AI2(AI3)
+
–
BUF
VR, -VR
generation
circuit
-VR
VR
VIN
GND
BF
S12(S13)
VR = -VRref
S4(S5)
GND
S6
VRref
Rref
Thermistor
etc.
AI4
VR1
Resistance for
stabilization