Oscillator calibration register – osccal, Table 11, Atmega162/v – Rainbow Electronics ATmega162V User Manual
Page 37
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ATmega162/V
2513E–AVR–09/03
Reset Time-out. For more information on the pre-programmed calibration value, see the
section “Calibration Byte” on page 233.
Note:
1. The device is shipped with this option selected.
When this Oscillator is selected, start-up times are determined by the SUT Fuses as
shown in Table 12. XTAL1 and XTAL2 should be left unconnected (NC).
Note:
1. The device is shipped with this option selected.
Oscillator Calibration Register
– OSCCAL
• Bit 7 – Res: Reserved Bit
This bit is reserved bit in the ATmega162, and will always read as zero.
• Bits 6..0 – CAL6..0: Oscillator Calibration Value
Writing the calibration byte to this address will trim the Internal Oscillator to remove pro-
cess variations from the Oscillator frequency. This is done automatically during Chip
Reset. When OSCCAL is zero, the lowest available frequency is chosen. Writing non-
zero values to this register will increase the frequency of the Internal Oscillator. Writing
0x7F to the register gives the highest available frequency. The calibrated Oscillator is
used to time EEPROM and Flash access. If EEPROM or Flash is written, do not cali-
brate to more than 10% above the nominal frequency. Otherwise, the EEPROM or Flash
write may fail.
Table 11. Internal Calibrated RC Oscillator Operating Modes
CKSEL3:0
Nominal Frequency
0010
8.0 MHz
Table 12. Start-up Times for the Internal Calibrated RC Oscillator Clock Selection
SUT1:0
Start-up Time from Power-
down and Power-save
Additional Delay from
Reset (V
CC
= 5.0V)
Recommended Usage
00
6 CK
–
BOD enabled
01
6 CK
4.1 ms
Fast rising power
10
6 CK
65 ms
Slowly rising power
11
Reserved
Bit
7
6
5
4
3
2
1
0
–
CAL6
CAL5
CAL4
CAL3
CAL2
CAL1
CAL0
OSCCAL
Read/Write
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
Device Specific Calibration Value