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Section 20 USB Function Module
Rev. 4.00 Sep. 14, 2005 Page 783 of 982
REJ09B0023-0400
(1) Transition from normal operation to stall
(1-1)
(2) When transaction is performed when internal status bit is set, and Clear Feature is sent
(2-1)
STALL handshake
Transaction request
STALL handshake
(2-2)
Clear Feature command
(3) When Clear Feature is sent before transaction is performed
(3-1)
1. In case of USB
specification
violation, etc., USB
function module
stalls endpoint
automatically
1. Transmission of
STALL handshake
1. Internal status bit
cleared to 0
2. USBEPSTL not
changed
1. USBEPSTL cleared
to 0 by application
2. IN/OUT token
received from host
3. Internal status bit
already set to 1
4. USBEPSTL not
referenced
5. Internal status bit
not changed
Normal status restored
Internal status bit
0 → 1
USBEPSTL
0
Internal status bit
1
USBEPSTL
0
Internal status bit
1
USBEPSTL
0
Internal status bit
1 → 0
USBEPSTL
0
Stall status maintained
To (2-1) or (3-1)
Figure 20.14 Automatic Stall by USB Function Module