UM10360 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
User manual Rev. 3 — 19 December 2013 292 of 841
NXP Semiconductors
UM10360
Chapter 13: LPC176x/5x USB OTG
Figure 43 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 42. 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
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