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11.5 Operation of A/D Converter
s Operation of A/D Conversion Function
The following describes the operation of the A/D converter. From activation to completion of A/D
conversion requires approximately 44 instruction cycles.
1. On activation, A/D conversion sets the conversion-in-progress flag bit (ADC1: ADMV = "1")
and connects the sample hold circuit to the specified analog input pin.
2. The internal sample hold capacitor captures the voltage at the analog input pin for
approximately 8 instruction cycles. The capacitor holds the voltage until the A/D conversion
completes.
3. The comparator compares the voltage captured by the sample hold capacitor with the A/D
converter reference voltage starting from the most significant bit (MSB) and ending with the
least significant bit (LSB), and transfers each bit sequentially to the ADCD register.
4. When the complete result has been transferred to the ADCD register, the conversion-in-
progress flag bit is cleared (ADC1: ADMV = "0") and the interrupt request flag bit is set
(ADC1: ADI = "1").
s Activating Sense Function
r Software activation
Figure 11.5-3 "Sense Function (Software Activation) Settings" shows the settings required for
software activation of the sense function.
Figure 11.5-3 Sense Function (Software Activation) Settings
On activation the sense function starts the operation of the sense function.
r Continuous activation
Figure 11.5-4 "Sense Function (Continuous Activation) Settings" shows the settings required for
continuous activation of the sense function.
Figure 11.5-4 Sense Function (Continuous Activation) Settings
When continuous activation is enabled, the rising edge of the selected input clock activates the
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
ADC1
ANS3
ANS2
ANS1
ANS0
ADI
ADMV
SIFM
AD
0
ADC2
—
ADCK
ADIE
ADMD
EXT
RESV
10
1
ADCD
Sets the compare voltage.
: Used bit
: Unused bit
1 : Set "1".
0 : Set "0".
1
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3Bit 2Bit 1Bit 0
ADC1
ANS3
ANS2
ANS1
ANS0
ADI
ADMV
SIFM
AD
0
ADC2
—
ADCK
ADIE
ADMD
EXT
RESV
11
1
ADCD
Sets the compare voltage.
: Used bit
: Unused bit
1 : Set "1".
0: Set "0".