Registers Used In A/D Converter - NEC 78K0 User Manual

11.3 Registers Used in A/D Converter

The following five registers are used to control the A/D converter.
• A/D converter mode register (ADM)
• Analog input channel specification register (ADS)
• A/D conversion result register (ADCR)
• Power-fail comparison mode register (PFM)
• Power-fail comparison threshold register (PFT)
(1) A/D converter mode register (ADM)
This register sets the conversion time for analog input to be A/D converted, and starts/stops conversion.
ADM can be set by a 1-bit or 8-bit memory manipulation instruction.
RESET input clears this register to 00H.
Address: FF28H
Symbol
ADM
Notes 1. Set so that the A/D conversion time is as follows.
• Standard products, (A) grade products: 14
• (A1) grade products:
• (A2) grade products:
222
CHAPTER 11 A/D CONVERTER
Figure 11-2. Format of A/D Converter Mode Register (ADM)
After reset: 00H
<7> 6 5
ADCS 0 FR2
ADCS A/D conversion operation control
0 Stops conversion operation
1 Enables conversion operation
FR2 FR1 FR0
0 0 0
0 0 1
0 1 0
1 0 0
1 0 1
1 1 0
Other than above
ADCE Boost reference voltage generator operation control
0 Stops operation of reference voltage generator
1 Enables operation of reference voltage generator
User's Manual U16227EJ2V0UD
R/W
4 3 2
FR1 FR0 0
Conversion time selection
f = 2 MHz f = 8.38 MHz f
X X
µ
µ
288/f
144 s 34.3 s
X
µ µ
240/f 120 s 28.6 s
X
µ
µ
192/f 96 s
22.9 s
X
µ
µ
144/f
72 s 17.2 s
X
µ µ
120/f
60 s 14.3 s
X
µ
µ
96/f 48 s
11.5 s
X
Setting prohibited
µ
s or longer but less than 100
µ
14 s or longer but less than 60
µ
16 s or longer but less than 48
1 <0>
0 ADCE
Note 1
= 10 MHz
X
µ
28.8 s
µ
24.0 s
µ
19.2 s
µ
14.4 s
µ
12.0 s
µ
9.6 s
Note 2
µ
s
µ
s
µ
s