ATmega16A Atmel Corporation, ATmega16A Datasheet - Page 221

• Manufacturer Part Number: ATmega16A
• Manufacturer: Atmel Corporation

Specifications of ATmega16A

• Flash (kbytes): 16 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 32
• Ext Interrupts: 3
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 1
• Eeprom (bytes): 512
• 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: 3
• Output Compare Channels: 4
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

22.9
22.9.1
8154B–AVR–07/09
Register Description
ADMUX – ADC Multiplexer Selection Register
Table 22-2.
Example:
• 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
(ADIF in ADCSRA is set). The internal voltage reference options may not be used if an external
reference voltage is being applied to the AREF pin.
Table 22-3.
• Bit 5 – ADLAR: ADC Left Adjust Result
The ADLAR bit affects the presentation of the ADC conversion result in the ADC Data Register.
Write one to ADLAR to left adjust the result. Otherwise, the result is right adjusted. Changing the
ADLAR bit will affect the ADC Data Register immediately, regardless of any ongoing conver-
sions. For a complete description of this bit, see
page
Bit
Read/Write
Initial Value
V
:.
V
V
V
:.
V
V
REFS1
ADCn
ADCm
ADCm
ADCm
ADCm
ADCm
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
ADCL will thus read 0x00, and ADCH will read 0x9C. Writing zero to ADLAR right adjusts
the result: ADCL = 0x70, ADCH = 0x02.
0
0
1
1
224.
+ 1/512 V
- 1/512 V
- 511/512 V
- V
REF
REFS0
/GAIN
Correlation between Input Voltage and Output Codes (Continued)
Voltage Reference Selections for ADC
0
1
0
1
REFS1
REF
REF
R/W
7
0
REF
/GAIN
/GAIN
/GAIN
Voltage Reference Selection
AREF, Internal Vref turned off
AVCC with external capacitor at AREF pin
Reserved
Internal 2.56V Voltage Reference with external capacitor at AREF pin
REFS0
R/W
6
0
ADLAR
R/W
5
0
Read code
:.
0x001
0x000
0x3FF
:.
0x201
0x200
MUX4
R/W
4
0
“ADCL and ADCH – The ADC Data Register” on
MUX3
R/W
3
0
Corresponding Decimal Value
:.
1
0
-1
:.
-511
-512
MUX2
R/W
2
0
Table
MUX1
R/W
1
0
ATmega16A
22-3. If these bits are
MUX0
R/W
0
0
ADMUX
221