atmega32u4-16mu ATMEL Corporation, atmega32u4-16mu Datasheet - Page 287

• Manufacturer Part Number: atmega32u4-16mu
• Description: Atmega32u4 8-bit Avr Microcontroller With 32k Bytes Of Isp Flash And Usb Controller
• Manufacturer: ATMEL Corporation

23.7
7766A–AVR–03/08
Address Setup
Figure 23-2. Endpoint activation flow:
As long as the endpoint is not correctly configured (CFGOK cleared), the hardware does not
acknowledge the packets sent by the host.
CFGOK is will not be sent if the Endpoint size parameter is bigger than the DPRAM size.
A clear of EPEN acts as an endpoint reset (see Section 23.3, page 285 for more details). It also
performs the next operation:
See Section 22.7, page 279 for more details about the memory allocation/reorganization.
The USB device address is set up according to the USB protocol:
ADDEN and UADD shall not be written at the same time.
UADD contains the default address 00h after a power-up or USB reset.
• The configuration of the endpoint is kept (EPSIZE, EPBK, ALLOC kept)
• It resets the data toggle field.
• The DPRAM memory associated to the endpoint is still reserved.
• the USB device, after power-up, responds at address 0
• the host sends a SETUP command (SET_ADDRESS(addr)),
• the firmware handles this request, and records that address in UADD, but keep ADDEN
• the USB device firmware sends an IN command of 0 bytes (IN 0 Zero Length Packet),
• then, the firmware can enable the USB device address by setting ADDEN. The only accepted
cleared,
address by the controller is the one stored in UADD.
Endpoint activated
Yes
UECFG0X
UECFG1X
CFGOK=1
Activation
Endpoint
EPEN=1
UENUM
EPNUM=x
EPTYPE
EPSIZE
ALLOC
EPDIR
EPBK
...
No
ERROR
Select the endpoint
Activate the endpoint
Configure:
Configure:
Allocation and reorganization of
the memory is made on-the-fly
Test the correct endpoint
configuration
- the endpoint direction
- the endpoint type
- the endpoint size
- the bank parametrization
ATmega32U4
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