ATmega32U4 Atmel Corporation, ATmega32U4 Datasheet - Page 143

• Manufacturer Part Number: ATmega32U4
• Manufacturer: Atmel Corporation

Specifications of ATmega32U4

• Flash (kbytes): 32 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 14
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 26
• Ext Interrupts: 13
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 12
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 3.3
• Eeprom (bytes): 1024
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• 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: 12
• Input Capture Channels: 2
• Pwm Channels: 8
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

15.4
7766F–AVR–11/10
Output Compare Unit
The comparator continuously compares TCNT4 with the Output Compare Registers (OCR4A,
OCR4B, OCR4C and OCR4D). Whenever TCNT4 equals to the Output Compare Register, the
comparator signals a match. A match will set the Output Compare Flag (OCF4A, OCF4B or
OCF4D) at the next timer clock cycle. If the corresponding interrupt is enabled, the Output Com-
pare Flag generates an Output Compare interrupt. The Output Compare Flag is automatically
cleared when the interrupt is executed. Alternatively, the flag can be cleared by software by writ-
ing a logical one to its I/O bit location. The Waveform Generator uses the match signal to
generate an output according to operating mode set by the PWM4x, WGM40 and Compare Out-
put mode (COM4x1:0) bits. The top and bottom signals are used by the Waveform Generator for
handling the special cases of the extreme values in some modes of operation
Operation” on page
Figure 15-4. Output Compare Unit, Block Diagram
The OCR4x Registers are double buffered when using any of the Pulse Width Modulation
(PWM) modes. For the normal mode of operation, the double buffering is disabled. The double
buffering synchronizes the update of the OCR4x Compare Registers to either top or bottom of
the counting sequence. The synchronization prevents the occurrence of odd-length, non-sym-
metrical PWM pulses, thereby making the output glitch-free. See
During the time between the write and the update operation, a read from OCR4A, OCR4B,
OCR4C or OCR4D will read the contents of the temporary location. This means that the most
recently written value always will read out of OCR4A, OCR4B, OCR4C or OCR4D.
BOTTOM
149.).
FOCn
OCRnx
TOP
10-BIT OCRnx
Figure 15-4
Waveform Generator
=
shows a block diagram of the Output Compare unit.
8-BIT DATA BUS
(10-bit Comparator )
OCWnx
TCnH
10-BIT TCNTn
ATmega16/32U4
TCNTn
COMnX1:0
PWMnx
WGMn0
Figure 15-5
OCFnx (Int.Req.)
for an example.
(See “Modes of
143