ATmega32U4 Atmel Corporation, ATmega32U4 Datasheet - Page 261

• 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

21.10 PAD suspend
7766F–AVR–11/10
EPEN=1
ALLOC=1
The following figure illustrates the allocation and reorganization of the USB memory in a typical
example:
Table 21-1.
Note that:
The next figures illustrates the pad behaviour:
• First, Endpoint 0 to Endpoint 5 are configured, in the growing order. The memory of each is
• Then, the Endpoint 3 is disabled (EPEN=0), but its memory reservation is internally kept by
• Its ALLOC bit is cleared: the Endpoint 4 “slides” down, but the Endpoint 5 does not “slide”.
• Finally, if the firmware chooses to reconfigure the Endpoint 3, with a bigger size. The
• the data of Endpoint 0 are never lost whatever the activation or deactivation of the higher
• Deactivate and reactivate the same Endpoint with the same parameters does not lead to a
• CFGOK is set by hardware even in the case where there is a “conflict” in the memory
• In the “idle” mode, the pad is put in low power consumption mode.
• In the “active” mode, the pad is working.
Free memory
Endpoints
reserved in the DPRAM.
the controller.
controller reserved the memory after the Endpoint 2 memory and automatically “slide” the
Endpoint 4. The Endpoint 5 does not move and a memory conflict appear, in that both
Endpoint 4 and 5 use a common area. The data of those endpoints are potentially lost.
Endpoint. Its data is lost if it is deactivated.
“slide” of the higher endpoints. For those endpoints, the data are preserved.
allocation.
activation
5
4
3
2
1
0
Allocation and reorganization USB memory flow
Endpoint Disable
Free memory
(ALLOC=1)
EPEN=0
5
4
2
1
0
Free its memory
Free memory
Lost memory
(ALLOC=0)
5
4
2
1
0
ATmega16/32U4
3 (bigger size)
Free memory
Activatation
Endpoint
4
2
1
0
5
Conflict
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