Clear Buffer; Validate Buffer; Set Endpoint Status; Acknowledge Setup - Philips PDIUSBD12 Product Data

Philips Semiconductors

11.3.7 Clear buffer

11.3.8 Validate buffer

11.3.9 Set endpoint status

11.3.10 Acknowledge setup

9397 750 09238
Product data
successful transaction. The exception is during DMA operation on the main endpoint
(endpoint 2), in which case the pointer is automatically pointed to the second buffer
after reaching the boundary (double buffering scheme).
Code (Hex) — F2
Transaction — none
When a packet is received completely, an internal endpoint buffer full flag is set. All
subsequent packets will be refused by returning a NAK. 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.
Code (Hex) — FA
Transaction — 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.
Code (Hex) — 40 to 45
Transaction — 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.
STALLED: A '1' indicates the endpoint is stalled.
Fig 14. Set endpoint status: bit allocation.
Code (Hex) — F1
Transaction — none
Rev. 08 — 20 December 2001
PDIUSBD12
USB interface device with parallel bus
© Koninklijke Philips Electronics N.V. 2001. All rights reserved.
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