Input Voltage And Conversion Results; Relations Between Analog Input Voltage And A/D Conversion Result - NEC PD78081(A) User Manual

10.4.2 Input voltage and conversion results

The relation between the analog input voltage input to the analog input pins (ANI0 to ANI7) and the A/D conversion
result (the value stored in A/D conversion result register (ADCR)) is shown by the following expression.
V
IN
ADCR = INT (
AV
REF
or
AV
(ADCR – 0.5)
256
Where, INT( ) : Function which returns integer parts of value in parentheses.
V : Analog input voltage
IN
AV : AV
REF
ADCR : Value of A/D conversion result register (ADCR)
Figure 10-6 shows the relation between the analog input voltage and the A/D conversion result.
Figure 10-6. Relations between Analog Input Voltage and A/D Conversion Result
A/D Conversion
Results
(ADCR)
128
CHAPTER 10 A/D CONVERTER
256 + 0.5)
REF
V < (ADCR + 0.5)
IN
pin voltage
REF
255
254
253
3
2
1
0
1 1 3
512 256 512
AV
REF
256
2 5 3 507 254
256 512 256 512 256
Input Voltage/AV
REF
509 255 511
1
512 256 512