ATMEGA32U4-MU Atmel, ATMEGA32U4-MU Datasheet - Page 274

• Manufacturer Part Number: ATMEGA32U4-MU
• Description: MCU AVR 32K FLASH 16MHZ 44-QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA32U4-MU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 26
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2.5K 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
• Package: 44QFN EP
• Device Core: AVR
• Family Name: ATmega
• Maximum Speed: 16 MHz
• Operating Supply Voltage: 3.3|5 V
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 26
• Interface Type: EBI/I2S/SPI/TWI/USART/USB
• On-chip Adc: 12-chx10-bit
• Number Of Timers: 5
• For Use With: ATSTK524 - KIT STARTER ATMEGA32M1/MEGA32C1ATSTK600 - 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: ATMEGA32U4-16MU; ATMEGA32U4-16MU

22.14 IN endpoint management
22.14.1
7766F–AVR–11/10
Detailed description
IN packets are sent by the USB device controller, upon an IN request from the host. All the data
can be written by the CPU, which acknowledge or not the bank when it is full.Overview
The Endpoint must be configured first.
The TXINI bit is set by hardware when the current bank becomes free. This triggers an interrupt
if the TXINE bit is set. The FIFOCON bit is set at the same time. The CPU writes into the FIFO
and clears the FIFOCON bit to allow the USB controller to send the data. If the IN Endpoint is
composed of multiple banks, this also switches to the next data bank. The TXINI and FIFOCON
bits are automatically updated by hardware regarding the status of the next bank.
TXINI shall always be cleared before clearing FIFOCON.
The RWAL bit always reflects the state of the current bank. This bit is set if the firmware can
write data to the bank, and cleared by hardware when the bank is full.
The data are written by the CPU, following the next flow:
• When the bank is empty, an endpoint interrupt (EPINTx) is triggered, if enabled (TXINE set)
• The CPU acknowledges the interrupt by clearing TXINI,
• The CPU can write the data into the current bank (write in UEDATX),
• The CPU can free the bank by clearing FIFOCON when all the data are written, that is:
and TXINI is set. The CPU can also poll TXINI or FIFOCON, depending the software
architecture choice,
Example with 1 IN data bank
Example with 2 IN data banks
FIFOCON
FIFOCON
TXINI
TXINI
SW
SW
write data from CPU
write data from CPU
NAK
BANK 0
BANK 0
SW
SW
IN
IN
SW
write data from CPU
BANK 1
(bank 0)
(bank 0)
DATA
DATA
SW
HW
HW
ACK
ACK
ATmega16/32U4
SW
SW
write data from CPU
write data from CPU
IN
BANK0
BANK 0
(bank 1)
DATA
SW
IN
ACK
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