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EZ-USB FX2 Technical Reference Manual
Page 15-72 EZ-USB FX2 Technical Reference Manual v2.1
off completing the CONTROL transfer until the device has had time to respond to a
request.Clear the HSNAK bit (by writing 1 to it) to instruct the USB core to ACK the status
stage of the transfer.
Bit 1 BUSY EP0 Buffer Busy
BUSY is a read-only bit that is automatically cleared when a SETUP token arrives. The BUSY
bit is set by writing a byte count to EP0BCL.
Bit 0 STALL EP0 Stalled
STALL is a read/write bit that is automatically cleared when a SETUP token arrives. The
STALL bit is set by writing a 1 to the register bit.
While STALL=1, the USB core sends the STALL PID for any IN or OUT token. This can occur
in either the data or handshake phase of the CONTROL transfer.
To indicate an endpoint stall on endpoint zero, set both STALL and HSNAK bits. Setting the STALL
bit alone causes endpoint zero to NAK forever because the host keeps the control transfer pend-
ing.
15.11.8 Endpoint 1 OUT/IN Control and Status
Figure 15-78. Endpoint 1 OUT/IN Control and Status
Bit 1 BUSY OUT/IN Endpoint Busy
The BUSY bit indicates the status of the endpoints OUT Buffer EP1OUTBUF. The USB core
sets BUSY=0 when the host data is available in the OUT buffer. The firmware sets BUSY=1 by
loading the endpoints byte count register.
When BUSY=1, endpoint RAM data is invalidthe endpoint buffer has been emptied by the
firmware and is waiting for new OUT data from the host, or it is the process of being loaded
over the USB. BUSY=0 when the USB OUT transfer is complete and endpoint RAM data in
EP1OUTCS Endpoint 1 OUT Control and Status E6A1
EP1INCS Endpoint 1 IN Control and Status E6A2
b7 b6 b5 b4 b3 b2 b1 b0
0 0 0 0 0 0 BUSY STALL
R/W R/W R/W R/W R/W R/W R R/W
0 0 0 0 0 0 0 0
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