ATAVRSB202 Atmel, ATAVRSB202 Datasheet - Page 32

• Manufacturer Part Number: ATAVRSB202
• Description: KIT BATT MGMT FOR ATMEGA32HVB
• Manufacturer: Atmel

Specifications of ATAVRSB202

• Main Purpose: *
• Embedded: *
• Utilized Ic / Part: *
• Primary Attributes: *
• Secondary Attributes: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

9.8
9.8.1
9.8.2
9.8.3
8042B–AVR–06/10
Register Description
FOSCCAL – Fast RC Oscillator Calibration Register
MCUCR – MCU Control Register
CLKPR – Clock Prescale Register
• Bits 7:0 – FCAL[7:0]: Fast RC Oscillator Calibration Value
The Fast RC Oscillator Calibration Register is used to trim the Fast RC Oscillator to remove pro-
cess variations from the oscillator frequency. The factory-calibrated value is automatically
written to this register during chip reset, giving an oscillator frequency of approximately 8.0 MHz
at 25°C. The application software can write this register to change the oscillator frequency. The
oscillator can be run-time calibrated to any frequency in the range 7.3 - 8.1 MHz. Calibration out-
side that range is not guaranteed.
Note that this oscillator is used to time EEPROM and Flash write accesses, and these write
times will be affected accordingly. If the EEPROM or Flash are written, do not calibrate to more
than 8.1 MHz. Otherwise, the EEPROM or Flash write may fail.
The FCAL[7:5] bits determine the range of operation for the oscillator. Setting these bits to
0b000 gives the lowest frequency range, setting this bit to 0b111 gives the highest frequency
range. The frequency ranges are overlapping. A setting of for instance FOSCCAL = 0x1F gives
a higher frequency than FOSCCAL = 0x20.
The FCAL[4:0] bits are used to tune the frequency within the selected range. A setting of 0x00
gives the lowest frequency in that range, and a setting of 0x1F gives the highest frequency in the
range. Incrementing FCAL[4:0] by 1 will give a frequency increment of less than 1% in the fre-
quency range 7.3 - 8.1 MHz. With an accurate time reference, an oscillator accuracy of ±0.5%
can be achieved after calibration. The frequency will drift with temperature, so run-time calibra-
tion will be required to maintain the accuracy. Refer to
page 29
• Bit 5 – CKOE: Clock Output
When this bit is written to one, the CPU clock divided by 2 is output on the PB1 pin.
Bit
(0x66)
Read/Write
Initial Value
Bit
0x35 (0x55)
Read/Write
Initial Value
Bit
(0x61)
Read/Write
Initial Value
for details.
FCAL7
R/W
CLKPCE
7
R/W
-–
R
7
0
7
0
FCAL6
R/W
6
R
6
–
0
R
6
–
0
FCAL5
R/W
5
CKOE
R/W
R
5
0
–
Device Specific Calibration Value
5
0
FCAL4
R/W
4
R
4
0
–
PUD
R/W
4
0
FCAL3
R/W
ATmega16HVB/32HVB
3
R
3
–
0
”OSI – Oscillator Sampling Interface” on
R
3
–
0
FCAL2
R/W
2
R
2
0
–
R
2
–
0
FCAL1
CLKPS1
R/W
R/W
1
IVSEL
1
1
R/W
1
0
FCAL0
CLKPS0
R/W
0
R/W
IVCE
R/W
0
1
0
0
FOSCCAL
MCUCR
CLKPR
32