ATMEGA16U4-MU Atmel, ATMEGA16U4-MU Datasheet - Page 261

• Manufacturer Part Number: ATMEGA16U4-MU
• Description: MCU AVR 16K FLASH 16MHZ 44-QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA16U4-MU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 26
• Program Memory Size: 16KB (8K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 12x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-VQFN
• For Use With: ATSTK600 - DEV KIT FOR AVR/AVR32ATAVRDRAGON - KIT DRAGON 32KB FLASH MEM AVRATSTK500 - PROGRAMMER AVR STARTER KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ATMEGA16U4-16MU; ATMEGA16U4-16MU

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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