Operations Of A/D Conversion Functions - Fujitsu F2MC-8L F202RA Hardware Manual

CHAPTER 12 A/D CONVERTER
Figure 12.6-2 Setting A/D Conversion Functions (at Continuous Activation)
When continuous activation is enabled, A/D conversion is activated on a rising edge of the selected input
clock and the operations of A/D conversion functions are started. When continuous activation is disabled
(ADC2: EXT = 0), continuous activation is stopped and activation with software is possible.
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Operations of A/D Conversion Functions

The operations of the A/D converter are described here. It takes about 38 instruction cycles from activating
A/D conversion to completing it.
1. When A/D conversion is activated, the conversion in-progress flag bit is set (ADC1: ADMV = 1), and
the analog input set is connected to the sample hold circuit.
2. During about 16 instruction cycles, the voltage of the analog input is captured and held in the capacitor
for internal sample hold. This voltage is held until A/D conversion has been completed.
3. The comparator compares the voltage captured and held in the capacitor for sample hold with the
reference voltage for A/D conversion from the MSB to the LSB. The results are transferred to the
ADDH and ADDL registers in turn.
4. When all the results have been transferred to the ADDH and ADDL registers, the conversion in-
progress flag bit is cleared (ADC1: ADMV = 0), and the interrupt request flag bit is set (ADC1: ADI =
1).
274
bit7 bit6 bit5
ADC1 ANS2 ANS1 ANS0
ADC2
RESV4 RESV3
0 0
The results of A/D conversion are stored.
ADDH
The results of A/D conversion are stored.
ADDL
ADEN
: Used bit
: Unused bit
: Set "1"
1
: Set "0"
0
: Set "1" to an appropriate bit
bit4 bit3 bit2 bit1
ADI ADMV RESV0
ADCK ADIE RESV2 EXT
0 1
bit0
AD
RESV1
1