atmega32u4-16mu ATMEL Corporation, atmega32u4-16mu Datasheet - Page 325

• Manufacturer Part Number: atmega32u4-16mu
• Description: Atmega32u4 8-bit Avr Microcontroller With 32k Bytes Of Isp Flash And Usb Controller
• Manufacturer: ATMEL Corporation

25.9
25.9.1
7766A–AVR–03/08
ADC Register Description
ADC Multiplexer Selection Register – ADMUX
Table 25-2.
Example 1:
Example 2:
• Bit 7:6 – REFS1:0: Reference Selection Bits
These bits select the voltage reference for the ADC, as shown in
changed during a conversion, the change will not go in effect until this conversion is complete
Bit
Read/Write
Initial Value
V
V
V
...
V
V
V
...
V
V
V
ADCn
ADCm
ADCm
ADCm
ADCm
ADCm
ADCm
ADCm
ADCm
– ADMUX = 0xE9, MUX5 = 0 (ADC1 - ADC0, 10x gain, 2.56V reference, left adjusted
– Voltage on ADC1 is 300 mV, voltage on ADC0 is 500 mV.
– ADCR = 512 * 10 * (300 - 500) / 2560 = -400 = 0x270
– ADCL will thus read 0x00, and ADCH will read 0x9C.
– ADMUX = 0xF0, MUX5 = 0 (ADC0 - ADC1, 1x gain, 2.56V reference, left adjusted
– Voltage on ADC0 is 300 mV, voltage on ADC1 is 500 mV.
– ADCR = 512 * 1 * (300 - 500) / 2560 = -41 = 0x029 .
– ADCL will thus read 0x40, and ADCH will read 0x0A.
+ 0.999 V
+ 0.998 V
+ 0.001 V
- 0.001 V
- 0.999 V
- V
result)
Writing zero to ADLAR right adjusts the result: ADCL = 0x70, ADCH = 0x02.
result)
Writing zero to ADLAR right adjusts the result: ADCL = 0x00, ADCH = 0x29.
+ V
REF
REF
/GAIN
REFS1
/GAIN
Correlation Between Input Voltage and Output Codes
R/W
REF
REF
7
0
REF
REF
REF
/GAIN
/GAIN
/GAIN
/GAIN
/GAIN
REFS0
R/W
6
0
ADLAR
R/W
Read code
5
0
0x1FE
0x1FF
0x1FF
0x3FF
0x001
0x000
0x201
0x200
...
...
MUX4
R/W
4
0
Corresponding decimal value
511
511
510
...
1
0
-1
...
-511
-512
MUX3
R/W
3
0
MUX2
R/W
2
0
MUX1
R/W
1
0
Table
ATmega32U4
MUX0
R/W
0
0
25-3. If these bits are
ADMUX
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