ATmega48 Automotive Atmel Corporation, ATmega48 Automotive Datasheet - Page 302

• Manufacturer Part Number: ATmega48 Automotive
• Manufacturer: Atmel Corporation

Specifications of ATmega48 Automotive

• Flash (kbytes): 4 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 12
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 23
• Ext Interrupts: 24
• Usb Speed: No
• Usb Interface: No
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• 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): 0.5
• Eeprom (bytes): 256
• Self Program Memory: NO
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 125
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 6
• Input Capture Channels: 1
• Pwm Channels: 6
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

26.8
302
Precaution Against OSCCAL Discontinuity
ATmega48/88/168 Automotive
Figure 26-3. Dichotomic Algorithm Used for LIN Slave Clock Re-synchronization
The
value. For one correct re-synchronization, the frequency change must be kept on the same side
of the discontinuity (no change of OSCCAL[7]). Since there will be no device having frequency
changed by more than 10% (see
by more than 10%. Therefore, when calibration tries to cross the border because of subsequent
increase (or decrease) in OSCCAL values, then the routine must be stopped.
example: For parts operating in the lower part of the curve, if New_OSCCAL >127 then
New_OSCCAL = 127. Similar for parts operating on the high side of the discontinuity.
Figure 28-23
illustrates the on-purpose discontinuity of RC Frequency versus OSCCAL
Decrement
Increment
OSCCAL
OSCCAL
Figure
-2% < Delta(TBit) < 2%
Delta(TBit) > 2%
Delta(TBit) < -2%
28-21), thus no reason to change the frequency value
Measuring
actual TBit
N
N
Y
STOP:
Oscillator
Calibrated
7530I–AVR–02/10