ATmega32U4 Atmel Corporation, ATmega32U4 Datasheet - Page 305

• Manufacturer Part Number: ATmega32U4
• Manufacturer: Atmel Corporation

Specifications of ATmega32U4

• Flash (kbytes): 32 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 14
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 26
• Ext Interrupts: 13
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 12
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 3.3
• Eeprom (bytes): 1024
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 4
• Output Compare Channels: 12
• Input Capture Channels: 2
• Pwm Channels: 8
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

24.8
7766F–AVR–11/10
ADC Conversion Result
Figure 24-14. Differential Non-linearity (DNL)
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
Table 24-3 on page 307
0x3FF represents the selected reference voltage minus one LSB.
If differential channels are used, the result is:
where V
GAIN the selected gain factor and V
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 posi-
tive.
Table 82 shows the resulting output codes if the differential input channel pair (ADCn - ADCm) is
selected with a reference voltage of V
• Quantization Error: Due to the quantization of the input voltage into a finite number of codes,
• Absolute Accuracy: The maximum deviation of an actual (unadjusted) transition compared to
a range of input voltages (1 LSB wide) will code to the same value. Always ± 0.5 LSB.
an ideal transition for any code. This is the compound effect of offset, gain error, differential
error, non-linearity, and quantization error. Ideal value: ± 0.5 LSB.
Figure 24-15
IN
POS
is the voltage on the selected input pin and V
is the voltage on the positive input pin, V
Output Code
shows the decoding of the differential input range.
0x000
0x3FF
and
0
Table 24-4 on page
1 LSB
ADC
REF
REF
ADC
=
the selected voltage reference. The result is presented
.
(
----------------------------------------------------------------------- -
V
=
POS
V
--------------------------
IN
V
–
⋅
REF
308). 0x000 represents analog ground, and
V
1023
NEG
NEG
V
REF
REF
) GAIN 512
⋅
the voltage on the negative input pin,
the selected voltage reference (see
ATmega16/32U4
⋅
V
REF
Input Voltage
305