ISP1761BEUM Datasheet, PDF(87/164 Page) NXP Semiconductors – Hi-Speed Universal Serial Bus On-The-Go controller

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ISP1761BEUM Datasheet, PDF (87/164 Pages) NXP Semiconductors – Hi-Speed Universal Serial Bus On-The-Go controller

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NXP Semiconductors

ISP1761

Hi-Speed USB OTG controller

peripheral, and the A-device assumes the role of a host. The A-device detects that the

B-device can support HNP by getting the OTG descriptor from the B-device. The A-device

will then enable the HNP hand-off by using SetFeature (b_hnp_enable) and then go into

the suspend state. The B-device signals claiming the host role by de-asserting its pull-up

resistor. The A-device acknowledges by going into the peripheral state. The B-device then

assumes the role of a host and communicates with the A-device as long as it wishes.

When the B-device ï¬nishes communicating with the A-device, both the devices ï¬nally go

into the idle state. See Figure 15 and Figure 16.

9.3 Session Request Protocol (SRP)

As a dual-role device, the ISP1761 can initiate and respond to SRP. The B-device initiates

SRP by data line pulsing, followed by VBUS pulsing. The A-device can detect either data

line pulsing or VBUS pulsing.

9.3.1 B-device initiating SRP

The ISP1761 can initiate SRP by performing the following steps:

1. Detect initial conditions [read B_SESS_END and B_SE0_SRP (bits 7 and 8) of the

OTG Status register].

2. Start data line pulsing [set DP_PULLUP (bit 0) of the OTG Control (set) register to

logic 1].

3. Wait for 5 ms to 10 ms.

4. Stop data line pulsing [set DP_PULLUP (bit 0) of the OTG Control (clear) register to

logic 0].

5. Start VBUS pulsing [set VBUS_CHRG (bit 6) of the OTG Control (set) register to

logic 1].

6. Wait for 10 ms to 20 ms.

7. Stop VBUS pulsing [set VBUS_CHRG (bit 6) of the OTG Control (clear) register to

logic 0].

8. Discharge VBUS for about 30 ms [by using VBUS_DISCHRG (bit 5) of the OTG

Control (set) register], optional.

The B-device must complete both data line pulsing and VBUS pulsing within 100 ms.

9.3.2 A-device responding to SRP

The A-device must be able to respond to one of the two SRP events: data line pulsing or

VBUS pulsing. When data line pulsing is used, the ISP1761 can detect DP pulsing. This

means that the peripheral-only device must initiate data line pulsing through DP. A

dual-role device will always initiate data line pulsing through DP.

To enable the SRP detection through the VBUS pulsing, set A_B_SESS_VLD (bit 1) in the

OTG Interrupt Enable Fall and OTG Interrupt Enable Rise registers.

To enable the SRP detection through the DP pulsing, set DP_SRP (bit 2) in the OTG

Interrupt Enable Rise register.

ISP1761_5

Product data sheet

Rev. 05 â 13 March 2008

86 of 163

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