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

13.3 Registers Used in A/D Converter

The A/D converter uses the following six registers.
• A/D converter mode register (ADM)
• A/D port configuration register (ADPC)
• Analog input channel specification register (ADS)
• Port mode register 2 (PM2)
• 10-bit A/D conversion result register (ADCR)
• 8-bit A/D conversion result register (ADCRH)
(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 signal generation sets this register to 00H.
Address: FF28H
Symbol <7>
ADM ADCS
ADCS
0
1
ADCE
0
1
Notes 1. For details of FR2 to FR0, LV1, LV0, and A/D conversion, see Table 13-2 A/D Conversion Time
Selection.
2. The operation of the comparator is controlled by ADCS and ADCE, and it takes 1
start to operation stabilization. Therefore, when ADCS is set to 1 after 1
the time ADCE is set to 1, the conversion result at that time has priority over the first conversion
result. Otherwise, ignore data of the first conversion.
ADCS ADCE
0
0
1
1
Note Ignore data of the first conversion because it is not guaranteed range.
CHAPTER 13 A/D CONVERTER
Figure 13-3. Format of A/D Converter Mode Register (ADM)
After reset: 00H R/W
6 5
Note 1
0 FR2
Stops conversion operation
Enables conversion operation
Stops comparator operation
Enables comparator operation (comparator: 1/2AV
Table 13-1. Settings of ADCS and ADCE
0 Stop status (DC power consumption path does not exist)
Conversion waiting mode (comparator: 1/2AV
1
consumes power)
0 Conversion mode (comparator operation stopped
1 Conversion mode (comparator: 1/2AV
Preliminary User's Manual U17260EJ3V1UD
4 3 2
Note 1 Note 1 Note 1
FR1 FR0 LV1
A/D conversion operation control
Comparator operation control
operation)
REF
A/D Conversion Operation
operation, only comparator
REF
Note
operation)
REF
1 <0>
Note 1
LV0 ADCE
Note 2
µ
s from operation
µ
s or more has elapsed from
)
307