ATmega64 Atmel Corporation, ATmega64 Datasheet - Page 43

• Manufacturer Part Number: ATmega64
• Manufacturer: Atmel Corporation

Specifications of ATmega64

• Flash (kbytes): 64 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 53
• Ext Interrupts: 8
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 2
• 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: No
• Crypto Engine: No
• Sram (kbytes): 4
• Eeprom (bytes): 2048
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 4
• Output Compare Channels: 8
• Input Capture Channels: 2
• Pwm Channels: 7
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

Calibrated Internal
RC Oscillator
OSCCAL – Oscillator
Calibration Register
2490Q–AVR–06/10
(1)
The calibrated internal RC Oscillator provides a fixed 1.0 MHz, 2.0 MHz, 4.0 MHz, or 8.0 MHz
clock. All frequencies are nominal values at 5V and 25°C. This clock may be selected as the
system clock by programming the CKSEL Fuses as shown in
with no external components. The CKOPT Fuse should always be unprogrammed when using
this clock option. During reset, hardware loads the calibration byte into the OSCCAL Register
and thereby automatically calibrates the RC Oscillator. At 5V, 25°C and 1.0 MHz Oscillator fre-
quency selected, this calibration gives a frequency within ±3% of the nominal frequency. Using
run-time calibration methods as described in application notes available at www.atmel.com/avr it
is possible to achieve ±1% accuracy at any given V
used as the chip clock, the Watchdog Oscillator will still be used for the Watchdog Timer and for
the Reset Time-out. For more information on the preprogrammed calibration value, see the sec-
tion
Table 13. Internal Calibrated RC Oscillator Operating Modes
Note:
When this Oscillator is selected, start-up times are determined by the SUT Fuses as shown in
Table
Table 14. Start-up Times for the Internal Calibrated RC Oscillator Clock Selection
Note:
Note:
• Bits 7..0 – CAL7..0: Oscillator Calibration Value
Writing the calibration byte to this address will trim the internal Oscillator to remove process vari-
ations from the Oscillator frequency. During Reset, the 1 MHz calibration value which is located
in the signature row high byte (address 0x00) is automatically loaded into the OSCCAL Register.
If the internal RC is used at other frequencies, the calibration values must be loaded manually.
This can be done by first reading the signature row by a programmer, and then store the calibra-
tion values in the Flash or EEPROM. Then the value can be read by software and loaded into
the OSCCAL Register. When OSCCAL is zero, the lowest available frequency is chosen. Writing
Bit
(0x6F)
Read/Write
Initial Value
SUT1..0
10
00
01
11
“Calibration Byte” on page
(1)
14. XTAL1 and XTAL2 should be left unconnected (NC).
1. The device is shipped with this option selected.
1. The device is shipped with this option selected.
1. The OSCCAL Register is not available in ATmega103 compatibility mode.
CKSEL3..0
Start-up Time from Power-
0001
CAL7
0010
0011
0100
down and Power-save
R/W
7
(1)
CAL6
6 CK
6 CK
6 CK
R/W
6
CAL5
293.
R/W
5
Device Specific Calibration Value
CAL4
R/W
4
Additional Delay from
Reset (V
Reserved
CAL3
R/W
Nominal Frequency (MHz)
4.1 ms
3
65 ms
CC
–
CC
= 5.0V)
and Temperature. When this Oscillator is
CAL2
R/W
2
1.0
2.0
4.0
8.0
Table
CAL1
R/W
Recommended Usage
BOD enabled
Fast rising power
Slowly rising power
1
13. If selected, it will operate
ATmega64(L)
CAL0
R/W
0
OSCCAL
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