ATmega16M1 Automotive Atmel Corporation, ATmega16M1 Automotive Datasheet - Page 18

• Manufacturer Part Number: ATmega16M1 Automotive
• Manufacturer: Atmel Corporation

Specifications of ATmega16M1 Automotive

• Flash (kbytes): 16 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: 27
• Ext Interrupts: 27
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Uart: 1
• Can: 1
• Lin: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 11
• Adc Resolution (bits): 10
• Adc Speed (ksps): 125
• Analog Comparators: 4
• Resistive Touch Screen: No
• Dac Channels: 1
• Dac Resolution (bits): 10
• 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 150
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 14
• Input Capture Channels: 1
• Pwm Channels: 10
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

The lowest addresses in the program memory space are by default defined as the Reset and
Interrupt Vectors. The complete list of vectors is shown in
“Interrupts” on page
57. The list also
determines the priority levels of the different interrupts. The lower the address the higher is the
priority level. RESET has the highest priority, and next is ANACOMP0 – the Analog Compara-
tor 0 Interrupt. The Interrupt Vectors can be moved to the start of the Boot Flash section by
setting the IVSEL bit in the MCU Control Register (MCUCR). Refer to
“Interrupts” on page 57
for more information. The Reset Vector can also be moved to the start of the Boot Flash sec-
tion by programming the BOOTRST Fuse, see
“Boot Loader Support – Read-While-Write
Self-Programming ATmega16/32/64/M1/C1” on page
279.
3.8.1
Interrupt Behavior
When an interrupt occurs, the Global Interrupt Enable I-bit is cleared and all interrupts are dis-
abled. The user software can write logic one to the I-bit to enable nested interrupts. All
enabled interrupts can then interrupt the current interrupt routine. The I-bit is automatically set
when a Return from Interrupt instruction – RETI – is executed.
There are basically two types of interrupts. The first type is triggered by an event that sets the
interrupt flag. For these interrupts, the Program Counter is vectored to the actual Interrupt
Vector in order to execute the interrupt handling routine, and hardware clears the correspond-
ing interrupt flag. Interrupt flags can also be cleared by writing a logic one to the flag bit
position(s) to be cleared. If an interrupt condition occurs while the corresponding interrupt
enable bit is cleared, the interrupt flag will be set and remembered until the interrupt is
enabled, or the flag is cleared by software. Similarly, if one or more interrupt conditions occur
while the Global Interrupt Enable bit is cleared, the corresponding interrupt flag(s) will be set
and remembered until the Global Interrupt Enable bit is set, and will then be executed by order
of priority.
The second type of interrupts will trigger as long as the interrupt condition is present. These
interrupts do not necessarily have interrupt flags. If the interrupt condition disappears before
the interrupt is enabled, the interrupt will not be triggered.
When the AVR exits from an interrupt, it will always return to the main program and execute
one more instruction before any pending interrupt is served.
Note that the Status Register is not automatically stored when entering an interrupt routine,
nor restored when returning from an interrupt routine. This must be handled by software.
When using the CLI instruction to disable interrupts, the interrupts will be immediately dis-
abled. No interrupt will be executed after the CLI instruction, even if it occurs simultaneously
with the CLI instruction. The following example shows how this can be used to avoid interrupts
during the timed EEPROM write sequence.
Atmel ATmega16/32/64/M1/C1
18
7647G–AVR–09/11