ATTINY461-20SUR Atmel, ATTINY461-20SUR Datasheet - Page 34
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ATTINY461-20SUR
Manufacturer Part Number
ATTINY461-20SUR
Description
MCU AVR 4KB FLASH 20MHZ 20SOIC
Manufacturer
Atmel
Series
AVR® ATtinyr
Datasheet
1.ATAVRMC321.pdf
(242 pages)
Specifications of ATTINY461-20SUR
Core Processor
AVR
Core Size
8-Bit
Speed
20MHz
Connectivity
USI
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
16
Program Memory Size
4KB (2K x 16)
Program Memory Type
FLASH
Eeprom Size
256 x 8
Ram Size
256 x 8
Voltage - Supply (vcc/vdd)
2.7 V ~ 5.5 V
Data Converters
A/D 11x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
*
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
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ATtiny261/461/861
• Bits 6:4 – Res: Reserved Bits
These bits are reserved and will always read as zero.
• Bits 3:0 – CLKPS3:0: Clock Prescaler Select Bits 3 - 0
These bits define the division factor between the selected clock source and the internal system
clock. These bits can be written run-time to vary the clock frequency to suit the application
requirements. As the divider divides the master clock input to the MCU, the speed of all synchro-
nous peripherals is reduced when a division factor is used. The division factors are given in
Table
To avoid unintentional changes of clock frequency, a special write procedure must be followed
to change the CLKPS bits:
Interrupts must be disabled when changing prescaler setting to make sure the write procedure is
not interrupted.
The CKDIV8 Fuse determines the initial value of the CLKPS bits. If CKDIV8 is unprogrammed,
the CLKPS bits will be reset to “0000”. If CKDIV8 is programmed, CLKPS bits are reset to
“0011”, giving a division factor of eight at start up. This feature should be used if the selected
clock source has a higher frequency than the maximum frequency of the device at the present
operating conditions. Note that any value can be written to the CLKPS bits regardless of the
CKDIV8 Fuse setting. The Application software must ensure that a sufficient division factor is
chosen if the selcted clock source has a higher frequency than the maximum frequency of the
device at the present operating conditions. The device is shipped with the CKDIV8 Fuse
programmed.
Table 6-13.
1. Write the Clock Prescaler Change Enable (CLKPCE) bit to one and all other bits in
2. Within four cycles, write the desired value to CLKPS while writing a zero to CLKPCE.
CLKPS3
CLKPR to zero.
6-13.
0
0
0
0
0
0
0
0
1
1
1
1
1
Clock Prescaler Select
CLKPS2
0
0
0
0
1
1
1
1
0
0
0
0
1
CLKPS1
0
0
1
1
0
0
1
1
0
0
1
1
0
CLKPS0
0
1
0
1
0
1
0
1
0
1
0
1
0
Clock Division Factor
Reserved
Reserved
Reserved
Reserved
128
256
16
32
64
1
2
4
8
2588E–AVR–08/10
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