ATTINY20-MMHR Atmel, ATTINY20-MMHR Datasheet - Page 23

• Manufacturer Part Number: ATTINY20-MMHR
• Description: MCU AVR 2KB FLASH 12MHZ 20QFN
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY20-MMHR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 12MHz
• Connectivity: I²C, SPI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 12
• Program Memory Size: 2KB (1K x 16)
• Program Memory Type: FLASH
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

6.5.3
8235B–AVR–04/11
OSCCAL – Oscillator Calibration Register
requirements. As the prescaler divides the master clock input to the MCU, the speed of all syn-
chronous peripherals is reduced accordingly. The division factors are given in
Table 6-4.
To avoid unintentional changes of clock frequency, a protected change sequence must be fol-
lowed to change the CLKPS bits:
At start-up, the CLKPS bits will be reset to 0b0011 to select the clock division factor of 8. The
application software must ensure that a sufficient division factor is chosen if the selected clock
source has a higher frequency than the maximum frequency of the device at the present operat-
ing conditions.
.
• Bits 7:0
The oscillator calibration register is used to trim the calibrated internal oscillator and remove pro-
cess variations from the oscillator frequency. A pre-programmed calibration value is
automatically written to this register during chip reset, giving the factory calibrated frequency as
specified in
Bit
0x39
Read/Write
Initial Value
1. Write the signature for change enable of protected I/O register to register CCP
2. Within four instruction cycles, write the desired value to CLKPS bits
CLKPS3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
–
Table 20-2, “Calibration Accuracy of Internal RC Oscillator,” on page
CAL[7:0]: Oscillator Calibration Value
CAL7
Clock Prescaler Select
R/W
7
0
CLKPS2
CAL6
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
R/W
6
0
CAL5
R/W
5
0
CLKPS1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
CAL4
R/W
4
0
CAL3
R/W
3
0
CLKPS0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
CAL2
R/W
2
0
CAL1
R/W
1
0
Clock Division Factor
CAL0
R/W
0
0
8 (default)
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
128
256
16
32
64
Table
1
2
4
ATtiny20
OSCCAL
174.
6-4.
23