Philips Semiconductors

Product specification

PDIUSBH11

Universal Serial Bus Hub

1997 Aug 01

12

Clear Buffer

Command

: F2h

Data

: None

When a packet is received completely, an internal endpoint buffer full flag is set. All subsequent packets will be refused by returning a NACK.

When the microcontroller has read the data, it should free the buffer by the Clear Buffer command. When the buffer is cleared new packets will

be accepted.

Validate Buffer

Command

: FAh

Data

: None

When the microprocessor has written data into an IN buffer, it should set the buffer full flag by the Validate Buffer command. This indicates that

the data in the buffer are valid and can be sent to the host when the next IN token is received.

Set Endpoint Status

Command

: 40–44h

Data

: Write 1 byte

A stalled control endpoint is automatically unstalled when it receives a SETUP token, regardless of the content of the packet. If the endpoint

should stay in its stalled state, the microcontroller can re–stall it.

When a stalled endpoint is unstalled (either by the Set Endpoint Status command or by receiving a SETUP token), it is also re–initialized. This

flushes the buffer and if it is an OUT buffer it waits for a DATA 0 PID, if it is an IN buffer it writes a DATA 0 PID.

Even when unstalled, writing Set Endpoint Status to ‘0’ initializes the endpoint.

X

7

X

6

X

5

X

4

X

3

X

2

X

1

0

0

POWER ON VALUE

STALLED

RESERVED

STALLED

A ‘1’ INDICATES THE ENDPOINT IS STALLED

SV00509

Acknowledge Setup

Command

: F1h

Data

: None

The arrival of a SETUP packet flushes the IN buffer and disables the Validate Buffer and Clear Buffer commands for both IN and OUT

endpoints.

The microcontroller needs to re–enable these commands by the Acknowledge Setup command. This ensures that the last SETUP packet stays

in the buffer and no packet can be sent back to the host until the microcontroller has acknowledged explicitly that it has seen the SETUP packet.

The microcontroller must send the Acknowledge Setup command to both the IN and OUT endpoints.