ATtiny20 Atmel Corporation, ATtiny20 Datasheet - Page 124

• Manufacturer Part Number: ATtiny20
• Manufacturer: Atmel Corporation

Specifications of ATtiny20

• Flash (kbytes): 2 Kbytes
• Pin Count: 14
• Max. Operating Frequency: 12 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 5
• Hardware Qtouch Acquisition: Yes
• Max I/o Pins: 12
• Ext Interrupts: 12
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 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: Yes
• Crypto Engine: No
• Sram (kbytes): 0.12
• Self Program Memory: NO
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 4
• Input Capture Channels: 1
• Pwm Channels: 3
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

15.13 Register Description
15.13.1
124
ATtiny20
ADMUX – ADC Multiplexer Selection Register
• Bit 7 – Res: Reserved Bit
This bit is reserved and will always read as zero.
• Bit 6 – REFS: Reference Selection Bit
This bits selects the voltage reference for the ADC, as shown in
Table 15-3.
If this bit is changed during a conversion, the change will not go in effect until this conversion is
complete (ADIF in ADCSR is set). Also note, that when these bits are changed, the next
conversion will take 25 ADC clock cycles.
• Bit 5 – REFEN
This bit is reserved for QTouch, always write as zero.
• Bit 4 – ADC0EN
This bit is reserved for QTouch, always write as zero.
• Bits 3:0 – MUX[3:0] : Analog Channel and Gain Selection Bits
The value of these bits selects which analog input is connected to the ADC, as shown in
15-4. Selecting channel ADC8 enables temperature measurement.
Table 15-4.
Bit
0x10
Read/Write
Initial Value
Single Ended Input
ADC0 (PA0)
ADC1 (PA1)
ADC2 (PA2)
ADC3 (PA3)
ADC4 (PA4)
ADC5 (PA5)
ADC6 (PA6)
ADC7 (PA7)
0V (AGND)
REFS
0
1
Voltage Reference Selections for ADC
Single-Ended Input channel Selections.
R
7
–
0
Voltage Reference Selection
V
Internal 1.1V voltage reference
REFS
R/W
CC
6
0
used as analog reference
REFEN
R/W
5
0
ADC0EN
R/W
4
0
MUX3
R/W
3
0
MUX2
R/W
2
0
Table
MUX1
R/W
15-3.
1
0
MUX[3:0]
0000
0001
0010
0011
0100
0101
0110
0111
1000
MUX0
R/W
0
0
8235B–AVR–04/11
ADMUX
Table