ATTINY861A-SU Atmel, ATTINY861A-SU Datasheet - Page 90

• Manufacturer Part Number: ATTINY861A-SU
• Description: IC, MCU, 8BIT, 8K FLASH, 20SOIC
• Manufacturer: Atmel

Specifications of ATTINY861A-SU

• Controller Family/series: ATtiny
• No. Of I/o's: 16
• Eeprom Memory Size: 512Byte
• Ram Memory Size: 512Byte
• Cpu Speed: 20MHz
• No.: RoHS Compliant
• Core Size: 8bit
• Program Memory Size: 8KB
• Oscillator Type: External, Internal
• Rohs Compliant: Yes

12.3
12.3.1
90
Clock Sources
ATtiny261A/461A/861A
Prescaler
counter value and so on. The definitions in
document.
Table 12-1.
The Timer/Counter is clocked internally, either from CK or PCK. See bits CSxx in
page 114
Figure 12-3
nous clocking mode and an asynchronous clocking mode. The synchronous clocking mode uses
the system clock (CK) as a clock timebase and asynchronous mode uses the fast peripheral
clock (PCK) as a clock time base. The PCKE bit from the PLLCSR register enables the asyn-
chronous mode when it is set (‘1’).
Figure 12-3. Timer/Counter1 Prescaler
In the asynchronous clocking mode the clock selections are from PCK to PCK/16384 and stop,
and in the synchronous clocking mode the clock selections are from CK to CK/16384 and stop.
The clock options are illustrated in
Control Register B” on page
The frequency of the fast peripheral clock is 64 MHz or 32 MHz in Low Speed mode (the LSM bit
in PLLCSR register is set to one). The Low Speed Mode is recommended to use when the sup-
ply voltage below 2.7 volts are used.
Constant
BOTTOM
CK
PCKE
PCK 64/32 MHz
MAX
TOP
and bit PCKE in
shows the Timer/Counter1 prescaler that supports two clocking modes, a synchro-
Definitions
CS10
CS11
CS12
CS13
Description
The counter reaches BOTTOM when it becomes 0x00
The counter reaches its MAXimum when it becomes 0xFF (decimal 255)
The counter reaches the TOP when it becomes equal to the highest value in the count
sequence. The TOP value can be assigned to be the fixed value 0xFF (MAX) or the
value stored in the OCR0A Register. The assignment depends on the mode of operation
S
A
T1CK
PSR1
“PLLCSR – PLL Control and Status Register” on page
113.
0
Figure 12-3
TIMER/COUNTER1 COUNT ENABLE
Table 12-1
and desribed in
T/C PRESCALER
14-BIT
are used extensively throughout the
“TCCR1B – Timer/Counter1
Table 12-17 on
118.
8197B–AVR–01/10