at85c51snd3b ATMEL Corporation, at85c51snd3b Datasheet - Page 103

• Manufacturer Part Number: at85c51snd3b
• Description: Single-chip Digital Audio Decoder - Encoder With Usb 2.0 Interface
• Manufacturer: ATMEL Corporation

Endpoint Activation
Address Setup
7632C–MP3–11/06
The endpoint is maintained under reset as long as the EPEN bit is not set.
The following flow must be respected in order to activate an endpoint:
Figure 60. 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 “Endpoint Reset” for more
details). It also performs the next operation:
•
•
•
See Section “Memory Management”, page 90 for more details about the memory
allocation/reorganization.
The USB device address is set up according to the USB protocol:
•
–
–
–
–
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
Clear DFCRDY to freeze the DFC transfer,
If the CPU EPNUM has to be changed: EPNUMS cleared, EPNUM =
endpoint
Read endpoint
Set DFCRDY. This resumes the DFC transfer.
Endpoint activated
0
Yes
UECFG0X
UECFG1X
CFGOK=1
Activation
Endpoint
EPEN=1
UENUM
EPNUM=x
EPTYPE
EPSIZE
ALLOC
EPDIR
EPBK
...
0
data (UEDATX)
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 Not Yet Disable feature
- the endpoint size
- the bank parametrization
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