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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
231 of 571
NXP Semiconductors
UM10316
Chapter 15: LPC29xx USB OTG interface
shows the actions that the OTG software stack should take in response to
the hardware actions setting REMOVE_PU, HNP_SUCCESS, AND HNP_FAILURE. The
relationship of the software actions to the Dual-Role B-Device states is also shown.
B-device states are in bold font with a circle around them.
Fig 54. Hardware support for B-device switching from peripheral state to host state
idle
set HNP_SUCCESS
set PORT_FUNC[0]
drive J on internal host controller port
and SE0 on U1
wait 25
μ
s for bus to settle
disconnect device controller from U1
set REMOVE_PU
bus suspended ?
set HNP_FAILURE,
clear B_HNP_TRACK,
clear PU_REMOVED
reconnect port U1 to the
device controller
reconnect port U1 to the
device controller
connect U1 to host controller
clear B_HNP_TRACK
clear PU_REMOVED
PU_REMOVED set?
PU_REMOVED set?
bus reset/resume detected?
connect from A-device detected?
bus reset/resume detected?
SE0 sent by host?
B_HNP_TRACK = 0
no
yes
yes
no
no
yes
yes
no
B_HNP_TRACK = 1 ?
no
no
no
yes