Atmel AT85DVK-07 Especificaciones descargar pdf (Pagina 103)

103

AT85C51SND3Bx

7632A–MP3–03/06

– Clear DFCRDY to freeze the DFC transfer,

– If the CPU EPNUM has to be changed: EPNUMS cleared, EPNUM =

endpoint

– Read endpoint

data (UEDATX)

– Set DFCRDY. This resumes the DFC transfer.

Endpoint Activation 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:

• 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.

See Section “Memory Management”, page 90 for more details about the memory

allocation/reorganization.

Address Setup The USB device address is set up according to the USB protocol:

• the USB device, after power-up, responds at address 0

Endpoint

Activation

CFGOK=1

ERROR

Yes

Endpoint activated

Activate the endpoint

Select the endpoint

EPEN=1

UENUM

EPNUM=x

Test the correct endpoint

configuration

UECFG1X

ALLOC

EPSIZE

EPBK

Configure:

- the endpoint size

- the bank parametrization

Allocation and reorganization of

the memory is made on-the-fly

UECFG0X

EPDIR

EPTYPE

...

Configure:

- the endpoint direction

- the endpoint type

- the Not Yet Disable feature

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