Datasheet

306
7766F–AVR–11/10
ATmega16/32U4
Figure 24-15. Differential Measurement Range
Example 1:
– ADMUX = 0xE9, MUX5 = 0 (ADC1 - ADC0, 10x gain, 2.56V reference, left adjusted
result)
– Voltage on ADC1 is 300 mV, voltage on ADC0 is 500 mV.
– ADCR = 512 * 10 * (300 - 500) / 2560 = -400 = 0x270
Table 24-2. Correlation Between Input Voltage and Output Codes
V
ADCn
Read code Corresponding decimal value
V
ADCm
+ V
REF
/GAIN 0x1FF 511
V
ADCm
+ 0.999 V
REF
/GAIN 0x1FF 511
V
ADCm
+ 0.998 V
REF
/GAIN 0x1FE 510
... ... ...
V
ADCm
+ 0.001 V
REF
/GAIN 0x001 1
V
ADCm
0x000 0
V
ADCm
- 0.001 V
REF
/GAIN 0x3FF -1
... ... ...
V
ADCm
- 0.999 V
REF
/GAIN 0x201 -511
V
ADCm
- V
REF
/GAIN 0x200 -512
0
Output Code
0x1FF
0x000
V
REF
Differential Input
Voltage (Volts)
0x3FF
0x200
- V
REF