Toshiba TC9314F Manual page 52

2. A/D Converter
The 6 bit resolution A/D converter is used for such purposes as measuring field intensity and battery
voltage. The A/D analog input can be multiplexed to the two external A/D analog inputs (pins AD
AD ), and can also be switched to the internal 1.5 V constant voltage (V
IN2
voltage (DC-REF) or power supply voltage (V
input voltage (AD input) is compared with the compare voltage corresponding to the AR0~AR5 data, and
the result is stored in the comparator output latch. The A/D conversion is performed whenever data are set
to the DA REF data 2 port (φL22). Therefore, always set the AR4 and AR5 bits of the A/D comparison data
(φL22) last.
The comparison result is output to the AD OUT port (φK22). The data can be read to data memory by the
IN2 instruction with the operand [C
The relation between the input voltage and the compare voltage is:
When AD input voltage < compare voltage: AD OUT = "0"
When AD input voltage > compare voltage: AD OUT = "1"
Use the following formula to calculate the compare voltage.
Compare voltage
The SEL0 and SEL1 bits switch between the AD
set to "0", AD is input. When SEL0 is set to "1" and SEL1 is set to "0", AD
IN1
SEL0 and SEL1 bits are set to "1", the A/D input is switched to the internal 1.5 V constant voltage (V
In this case, connect a capacitor (typ. 0.47 µF) to the AD
DD
= 2].
N
−
n 0.5
(where n is the AR0~AR5 data value [decimal] 63 > = n > = 1)
= V ×
REF
64
A/D Comparator Structure
) is used as the reference voltage (V
and AD inputs. When both SEL0 and SEL1 are
IN1 IN2
pin to stabilize the constant voltage.
IN2
52
TC9314F
IN1
). Normally, the external
EE
). The external
REF
is input. When both the
IN2
2003-07-03
and
).
EE