AT90PWM2/3/2B/3B
Figure 21-14. Differential Measurement Range
Output Code
0x1FF
0x000
0
Differential Input
VREF/Gain
- V
REF/Gain
0x3FF
Voltage (Volts)
0x200
Table 21-2. Correlation Between Input Voltage and Output Codes
VADCn
Read code
0x1FF
0x1FF
0x1FE
...
Corresponding decimal value
VADCm + VREF /GAIN
511
511
510
...
VADCm + 0.999 VREF /GAIN
VADCm + 0.998 VREF /GAIN
...
V
ADCm + 0.001 VREF /GAIN
0x001
0x000
0x3FF
...
1
VADCm
0
VADCm - 0.001 VREF /GAIN
...
-1
...
VADCm - 0.999 VREF /GAIN
VADCm - VREF /GAIN
0x201
0x200
-511
-512
Example 1:
–
–
–
ADMUX = 0xED (ADC3 - ADC2, 10x gain, 2.56V reference, left adjusted result)
Voltage on ADC3 is 300 mV, voltage on ADC2 is 500 mV.
ADCR = 512 * 10 * (300 - 500) / 2560 = -400 = 0x270
245
4317J–AVR–08/10
ATMEL [ ATMEL ]
