UPD784938 Datasheet, PDF (413/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 16 A/D CONVERTER
(2) Input voltage and conversion result
The relationship between the analog input voltage input to an analog input pin (ANI0 to ANI7) and the A/D conversion
result (value stored in ADCR) is shown by the following expression:
ADCR = INT( ^VIN × 256 + 0.5)
AVREF1
or
(ADCR – 0.5) × ^AVREF1 ≤ VIN < (ADCR + 0.5) × ^AVREF1
256
256
Remark INT( ): Function that returns the integer part of the value in ( )
VIN:
Analog input voltage
AVREF1: AVREF1 pin voltage
ADCR: ADCR value
Figure 16-7 shows the relationship between the analog input voltage and the A/D conversion result in graphic form.
Figure 16-7. Relationship between Analog Input Voltage and A/D Conversion Result
255
254
A/D conversion
result (ADCR) ²⁵³
3
2
1
0
1 1 3253
512 256 512 256 512 256
507 254 509 255 511 ₁
512 256 512 256 512
Input voltage/AVREF1
Preliminary User’s Manual U13987EJ1V0UM00
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