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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
234 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 TMR, HNP_SUCCESS, and HNP_FAILURE. The
relationship of the software actions to the Dual-Role A-Device states is also shown.
A-device states are shown in bold font with a circle around them.
Fig 56. Hardware support for A-device switching from host state to peripheral state
disconnect host controller from U1
set HNP_FAILURE,
clear A_HNP_TRACK
clear A_HNP_TRACK
set HNP_SUCCESS
connect device to U1 by clearing
PORT_FUNC[0]
bus reset detected?
OTG timer expired?
(TMR =1 )
resume detected?
connnect host controller back to U1
no
no
no
yes
yes
yes
yes
yes
idle
A_HNP_TRACK = 0
bus suspended ?
resume detected ?
no
no
A_HNP_TRACK = 1 ?
no