AT90PWM2 datasheet(255/365 Pages) ATMEL

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AT90PWM2/3

4317B–AVR–02/05

ADC Conversion Result

After the conversion is complete (ADIF is high), the conversion result can be found in

the ADC Result Registers (ADCL, ADCH).

For single ended conversion, the result is:

where V

IN is the voltage on the selected input pin and VREF the selected voltage refer-

ence (see Table 100 on page 257 and Table 101 on page 257). 0x000 represents

analog ground, and 0x3FF represents the selected reference voltage.

If differential channels are used, the result is:

where V

POS is the voltage on the positive input pin, VNEG the voltage on the negative

input pin, GAIN the selected gain factor and V

REF the selected voltage reference. The

result is presented in two’s complement form, from 0x200 (-512d) through 0x1FF

(+511d). Note that if the user wants to perform a quick polarity check of the result, it is

sufficient to read the MSB of the result (ADC9 in ADCH). If the bit is one, the result is

negative, and if this bit is zero, the result is positive. Figure 128 shows the decoding of

the differential input range.

Table 82 shows the resulting output codes if the differential input channel pair (ADCn -

ADCm) is selected with a reference voltage of V

REF.

Figure 128. Differential Measurement Range

ADC

1023

⋅

REF

--------------------------

ADC

POS

NEG

–

() GAIN 512

⋅⋅

REF

------------------------------------------------------------------------

Output Code

0x1FF

0x000

REF

Differential Input

Voltage (Volts)

0x3FF

0x200

- V

REF

/Gain

AT90PWM2 Datasheet(PDF) 255 Page - ATMEL Corporation

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