Microcontrollers User manual

User manual Rev. 02 — 19 December 2008 412 of 792

NXP Semiconductors

UM10237

Chapter 15: LPC24XX USB OTG controller

Figure 15–61 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 60. 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 μs 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?

bus reset/resume detected?

connect from A-device detected?

bus reset/resume detected?

SE0 sent by host?

B_HNP_TRACK = 0

yes

B_HNP_TRACK = 1 ?

yes