Copyright © 2014 Future Technology Devices International Limited

21

Document No.: FT_000646

FT120 USB DEVICE CONTROLLER WITH PARALLEL BUS IC

Datasheet Version 1.2

Clearance No.: FTDI#

291

Bit

Symbol

Reset

Description

7

Endpoint Stalled

0

0: endpoint is not stalled

1: endpoint is stalled

Table 6-12 Endpoint Buffer Status Register

6.3.5 Read Buffer

Command

: F0h

Data

: Read multiple bytes

The Read Buffer command is used to read the received packet from the selected endpoint OUT buffer.

The data in the endpoint buffer is organized as follows:

o

byte 0: reserved, don’t care

o

byte 1: length of payload packet

o

byte 2: Payload packet byte 1

o

byte 3: Payload packet byte 2

o

…

o

byte n: Payload packet byte n (n = packet length + 2)

For DMA read operation the first two bytes are skipped. Only the payload packet itself will be read and

stored in system memory.

6.3.6 Write Buffer

Command

: F0h

Data

: Write multiple bytes

The Write Buffer command is used to write payload packet to the selected endpoint IN buffer.

The data must be organized in the same way as described in the Read Buffer command. Byte 0 should

always be set to 00h.

For DMA write operation the first two bytes are skipped. Only the payload packet itself shall be written to

the selected endpoint OUT buffer. Buffer is validated when the max packet size is reached, or when the

DMA transfer is terminated by EOT_n (usually the last packet).