ATtiny167 Atmel Corporation, ATtiny167 Datasheet - Page 195

• Manufacturer Part Number: ATtiny167
• Manufacturer: Atmel Corporation

Specifications of ATtiny167

• Flash (kbytes): 16 Kbytes
• Pin Count: 20
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 8
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 16
• Ext Interrupts: 16
• Usb Speed: No
• Usb Interface: No
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• Lin: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 11
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 0.5
• 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: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 3
• Input Capture Channels: 1
• Pwm Channels: 9
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

17.5
8265B–AVR–09/10
Prescaling and Conversion Timing
Figure 17-3. ADC Prescaler
By default, the successive approximation circuitry requires an input clock frequency between
50 kHz and 200 kHz to get maximum resolution. If a lower resolution than 10 bits is needed,
the input clock frequency to the ADC can be higher than 200 kHz to get a higher sample rate.
The ADC module contains a prescaler, which generates an acceptable ADC clock frequency
from any CPU frequency above 100 kHz. The prescaling is set by the ADPS bits in ADCSRA
register. The prescaler starts counting from the moment the ADC is switched on by setting the
ADEN bit in ADCSRA register. The prescaler keeps running for as long as the ADEN bit is set,
and is continuously reset when ADEN is low.
When initiating a single ended conversion by setting the ADSC bit in ADCSRA register, the
conversion starts at the following rising edge of the ADC clock cycle.
A normal conversion takes 13 ADC clock cycles. The first conversion after the ADC is
switched on (ADEN in ADCSRA register is set) takes 25 ADC clock cycles in order to initialize
the analog circuitry.
The actual sample-and-hold takes place 1.5 ADC clock cycles after the start of a normal con-
version and 14.5 ADC clock cycles after the start of an first conversion. When a conversion is
complete, the result is written to the ADC Data Registers, and ADIF is set. In Single Conver-
sion mode, ADSC is cleared simultaneously. The software may then set ADSC again, and a
new conversion will be initiated on the first rising ADC clock edge.
When Auto Triggering is used, the prescaler is reset when the trigger event occurs. This
assures a fixed delay from the trigger event to the start of conversion. In this mode, the sam-
ple-and-hold takes place 2 ADC clock cycles after the rising edge on the trigger source signal.
Three additional CPU clock cycles are used for synchronization logic.
In Free Running mode, a new conversion will be started immediately after the conversion
completes, while ADSC remains high. For a summary of conversion times, see
CLK
ADEN
Start
IO
ADPS0
ADPS1
ADPS2
Reset
7-bit ADC Prescaler
Table
17-1.
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