
S1C62740 TECHNICAL HARDWARE
EPSON
I-97
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (A/D Converter)
Control the middle electric potential generation circuit as shown in
Table 4.12.5.
GNDON0, GNDON1:
GND generation circuit control
(F0HD3, D2)
GNDON1
GNDON0
Middle electric potential generation circuit
0
OFF (external impression)
0
1
ON (VDD side load driving capacity – small)
1
0
ON (VDD side load driving capacity – medium)
1
ON (VDD side load driving capacity – large)
Table 4.12.5
Control of the middle electric
potential generation circuit
When the externally impressing the GND level, set it to OFF and
when using a built-in middle electric potential generation circuit
set it according to the load connected to the VDD side.
When not using an A/D converter, set the circuit to OFF to reduce
current consumption.
At initial reset, these registers are set to "0".
VRON:
Reference voltage generation
circuit control
(F0HD0)
Controls the reference voltage generation circuit.
When "1" is written: ON
When "0" is written: OFF
Reading: Valid
The built-in reference voltage generation circuit goes ON when "1"
is written into the VRON and goes OFF when "0" is written into it.
When the circuit goes ON, it generate VR1 for resistance measure-
ment and VR2 for voltage measurement.
When the externally impressing the reference voltage VR1, set it to
OFF.
Also, when an A/D converter is not used, you should set the circuit
to OFF so as to reduce current consumption.
At initial reset, this register is set to "0".
VRAON:
Reference voltage internal
adjustment control
(F0HD1)
Turns the internal adjustment of the reference voltage ON and
OFF.
When "1" is written: ON
When "0" is written: OFF
Reading: Valid
Internal adjustment of the reference voltage is done by writing "1"
into the VRAON. When no external adjustment is done using a
built-in reference voltage generation circuit, you should turn the
internal adjustment ON.
When doing the adjustment from the outside, turn the internal
adjustment OFF.
At initial reset, this register is set to "0".