atmega32c1 ATMEL Corporation, atmega32c1 Datasheet - Page 32

• Manufacturer Part Number: atmega32c1
• Description: Atmega32m1 Automotive 8-bit Avr Microcontroller With 32k/64k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

5.5
32
Calibrated Internal RC Oscillator
ATmega32/64/M1/C1
Table 5-3.
Notes:
The CKSEL0 Fuse together with the SUT1..0 Fuses select the start-up times as shown in
5-4.
Table 5-4.
Notes:
By default, the Internal RC OScillator provides an approximate 8.0 MHz clock. Though voltage
and temperature dependent, this clock can be very accurately calibrated by the user. The device
is shipped with the CKDIV8 Fuse programmed. See
more details.
This clock may be selected as the system clock by programming the CKSEL Fuses as shown in
Table
the pre-programmed calibration value into the OSCCAL Register and thereby automatically cal-
CKSEL0
CKSEL3..1
0
0
0
0
1
1
1
1
101
110
111
5-1. If selected, it will operate with no external components. During reset, hardware loads
1. The frequency ranges are preliminary values. Actual values are TBD.
2. This option should not be used with crystals, only with ceramic resonators.
1. These options should only be used when not operating close to the maximum frequency of the
2. These options are intended for use with ceramic resonators and will ensure frequency stability
device, and only if frequency stability at start-up is not important for the application. These
options are not suitable for crystals.
at start-up. They can also be used with crystals when not operating close to the maximum fre-
quency of the device, and if frequency stability at start-up is not important for the application.
SUT1..0
Crystal Oscillator Operating Modes
Start-up Times for the Oscillator Clock Selection
00
01
10
00
01
10
11
11
Frequency Range
Start-up Time from
Power-down and
8.0 -16.0
0.9 - 3.0
3.0 - 8.0
Power-save
258 CK
258 CK
1K CK
1K CK
1K CK
16K CK
16K CK
16K CK
(1)
(2)
(2)
(2)
(1)
(1)
(MHz)
Additional Delay
Recommended Range for Capacitors C1 and
14CK + 4.1 ms
14CK + 4.1 ms
14CK + 4.1 ms
14CK + 65 ms
14CK + 65 ms
14CK + 65 ms
(V
from Reset
“System Clock Prescaler” on page 36
CC
14CK
14CK
= 5.0V)
C2 for Use with Crystals (pF)
12 - 22
12 - 22
12 - 22
Recommended Usage
Ceramic resonator, fast
rising power
Ceramic resonator, slowly
rising power
Ceramic resonator, BOD
enabled
Ceramic resonator, fast
rising power
Ceramic resonator, slowly
rising power
Crystal Oscillator, BOD
enabled
Crystal Oscillator, fast
rising power
Crystal Oscillator, slowly
rising power
7647A–AVR–02/08
Table
for