Registers Controlling A/D Converter - NEC mPD178054 Series User Manual

10.3 Registers Controlling A/D Converter

The following three registers control the A/D converter.
• A/D converter mode register 3 (ADM3)
• Analog input channel specification register 3 (ADS3)
• Power-fail comparison mode register 3 (PFM3)
(1) A/D converter mode register 3 (ADM3)
This register selects the conversion time of the analog input to be converted and starts or stops the conversion
operation.
ADM3 is set with a 1-bit or 8-bit memory manipulation instruction.
Reset input clears this register to 00H.
Figure 10-2. Format of A/D Converter Mode Register 3 (ADM3)
Symbol <7> 6
ADM3 ADCS3 0
ADCS3
0 Stops conversion operation
1 Enables conversion operation
FR32 FR31
0 0
0 0
0 1
1 0
1 0
1 1
Other than above
Cautions 1. The conversion result is undefined immediately after bit 7 (ADCS3) has been set to 1.
2. To change the data of bits 3 to 5 (FR30 to FR32), stop the A/D conversion operation.
Remarks 1. f : System clock oscillation frequency
X
2. ( ): f
X
CHAPTER 10 A/D CONVERTER
5 4 3
FR32 FR31 FR30
Control of A/D conversion operation
FR30 Selection of conversion time
(64.0 µ s)
0 288/f
X
(53.3 µ s)
1 240/f
X
(42.7 µ s)
0 192/f
X
(32.0 µ s)
0 144/f
X
(26.7 µ s)
1 120/f
X
(21.3 µ s)
0 96/f
X
Setting prohibited
= 4.5 MHz
User's Manual U15104EJ2V0UD
2 1 0 Address
0 0 0 FF12H
After reset R/W
00H R/W
133