AT90CAN32 Automotive Atmel Corporation, AT90CAN32 Automotive Datasheet - Page 159

• Manufacturer Part Number: AT90CAN32 Automotive
• Manufacturer: Atmel Corporation

Specifications of AT90CAN32 Automotive

• Flash (kbytes): 32 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 53
• Ext Interrupts: 8
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 2
• Can: 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): 2
• Eeprom (bytes): 1024
• Self Program Memory: YES
• 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: 4
• Output Compare Channels: 8
• Input Capture Channels: 2
• Pwm Channels: 7
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

14.10 Asynchronous operation of the Timer/Counter2
14.10.1
7682C–AUTO–04/08
Asynchronous Status Register – ASSR
The Output Compare Register A contains an 8-bit value that is continuously compared with the
counter value (TCNT2). A match can be used to generate an Output Compare interrupt, or to
generate a waveform output on the OC2A pin.
• Bit 7..5 – Reserved Bits
These bits are reserved for future use.
• Bit 4 – EXCLK: Enable External Clock Input
When EXCLK is written to one, and asynchronous clock is selected, the external clock input
buffer is enabled and an external clock can be input on Timer Oscillator 1 (TOSC1) pin instead
of a 32 kHz crystal. Writing to EXCLK should be done before asynchronous operation is
selected. Note that the crystal Oscillator will only run when this bit is zero.
• Bit 3 – AS2: Asynchronous Timer/Counter2
When AS2 is written to zero, Timer/Counter2 is clocked from the I/O clock, clk
Oscillator connected to the Timer/Counter2 Oscillator (TOSC) does nor run. When AS2 is written
to one, Timer/Counter2 is clocked from a crystal Oscillator connected to the Timer/Counter2
Oscillator (TOSC) or from external clock on TOSC1 depending on EXCLK setting. When the
value of AS2 is changed, the contents of TCNT2, OCR2A, and TCCR2A might be corrupted.
• Bit 2 – TCN2UB: Timer/Counter2 Update Busy
When Timer/Counter2 operates asynchronously and TCNT2 is written, this bit becomes set.
When TCNT2 has been updated from the temporary storage register, this bit is cleared by hard-
ware. A logical zero in this bit indicates that TCNT2 is ready to be updated with a new value.
• Bit 1 – OCR2UB: Output Compare Register2 Update Busy
When Timer/Counter2 operates asynchronously and OCR2A is written, this bit becomes set.
When OCR2A has been updated from the temporary storage register, this bit is cleared by hard-
ware. A logical zero in this bit indicates that OCR2A is ready to be updated with a new value.
• Bit 0 – TCR2UB: Timer/Counter Control Register2 Update Busy
When Timer/Counter2 operates asynchronously and TCCR2A is written, this bit becomes set.
When TCCR2A has been updated from the temporary storage register, this bit is cleared by
hardware. A logical zero in this bit indicates that TCCR2A is ready to be updated with a new
value.
If a write is performed to any of the three Timer/Counter2 Registers while its update busy flag is
set, the updated value might get corrupted and cause an unintentional interrupt to occur.
The mechanisms for reading TCNT2, OCR2A, and TCCR2A are different. When reading
TCNT2, the actual timer value is read. When reading OCR2A or TCCR2A, the value in the tem-
porary storage register is read.
Bit
Read/Write
Initial Value
R
7
–
0
R
6
–
0
R
5
–
0
EXCLK
R/W
4
0
AS2
R/W
3
0
TCN2UB
R
2
0
AT90CAN32/64/128
OCR2UB
R
1
0
TCR2UB
R
0
0
I/O
ASSR
and the crystal
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