Input Voltage And Conversion Results - NEC mPD780065 Series Preliminary User's Manual

11.4.2 Input voltage and conversion results

The relationship between the analog input voltage input to the analog input pins (ANI0 to ANI7) and the A/D
conversion result (stored in the A/D conversion result register (ADCR0)) is shown by the following expression.
V
IN
ADCR0 = INT (
AV
REF
or
AV
(ADCR0 – 0.5) ×
256
where, INT( ): Function which returns integer part of value in parentheses
V : Analog input voltage
IN
AV : AV
REF REF
ADCR0: A/D conversion result register (ADCR0) value
Figure 11-5 shows the relationship between the analog input voltage and the A/D conversion result.
Figure 11-5. Relationship between Analog Input Voltage and A/D Conversion Result
A/D conversion result
(ADCR0)
180
CHAPTER 11 A/D CONVERTER
× 256 + 0.5)
REF
≤ V < (ADCR0 + 0.5) ×
IN
pin voltage
255
254
253
3
2
1
0
1 1 3
512 256 512 256
Preliminary User's Manual U13420EJ2V0UM00
AV
REF
256
2 5 3 507 254 509
512 256 512 256 512
Input voltage/AV
REF
255 511 1
256 512