ATmega16HVB Atmel Corporation, ATmega16HVB Datasheet - Page 32

• Manufacturer Part Number: ATmega16HVB
• Manufacturer: Atmel Corporation

Specifications of ATmega16HVB

• Flash (kbytes): 16 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 8 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 8
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 17
• Ext Interrupts: 15
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 12
• Adc Speed (ksps): 1.9
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 1
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 4.0 to 25
• Operating Voltage (vcc): 4.0 to 25
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 4
• Input Capture Channels: 2
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

9.8
9.8.1
9.8.2
9.8.3
32
Register description
ATmega16HVB/32HVB
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 8.0MHz
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 7.3MHz - 8.1MHz. Calibration
outside 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 8.1MHz. 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 one will give a frequency increment of less than 1% in the fre-
quency range 7.3MHz - 8.1MHz. 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
calibration will be required to maintain the accuracy. Refer to
face” on 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
FCAL7
R/W
CLKPCE
7
R/W
-–
R
7
0
7
0
for details.
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
3
R
3
–
0
R
3
0
–
FCAL2
R/W
2
R
2
–
0
”OSI – Oscillator sampling inter-
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
8042D–AVR–10/11
FOSCCAL
MCUCR
CLKPR