Relations Between Analog Input Voltages And A/D Conversion Results - NEC PD78212 User Manual

A/D conversion continues until the CS bit is reset by software.
If data is written to the ADM register during conversion, conversion is initialized. If the CS bit is 1,
conversion is started from the beginning.
When the RESET signal is input, the ADCR register contents become undefined.
(2) Input voltage and conversion result
The analog voltages input to the analog input pins (AN0 through AN7) are related to the A/D conversion result
(value held in the ADCR), as follows:
V
IN
ADCR = INT(
AV
REF
or,
AV
REF
(ADCR - 0.5) ×
256
Remark INT( ) : Function returning the integer part of a value specified in ( )
V : Analog input voltage
IN
AV : AV pin voltage
REF REF
ADCR : Value in the ADCR register
Fig. 8-5 shows the relations between the analog voltages and the A/D conversion results.
Fig. 8-5 Relations between Analog Input Voltages and A/D Conversion Results
A/D conversion
result (ADCR)
× 256 + 0.5)
≤ V < (ADCR + 0.5) ×
IN
255
254
253
3
2
1
0
1 1 3 2
512 256 512 256
AV
REF
256
5 3 507 254 509 255
512 256 512 256 512 256
Input voltage/AV
REF
Chapter 8 A/D Converter
511
1
512
8
231