Table of Contents
Advertisement
USB OTG Controller
Table 64. OTG System Configuration Register 2 (OTG_SYSCON_2) (Continued)
Bit
Name
26:24
SRP_GPUVBUS
23
Reserved
† See Table 65, OTG_PADEN Source Status.
‡ See Table 66, HMC_PADEN: USB Signal Multiplexing Control Source.
204
Universal Serial Bus (USB)
Description
Session request protocol generation charge VBUS duration.This bit
controls the duration that the OTG controller attempts to charge VBUS
when acting as a default-B OTG device and requesting SRP.
0x0: OMAP5912 does not issue a VBUS charge pulse as part of its SRP
generation sequence.
0x1: VBUS is charged for 0.5 ms nominal.
0x2: During SRP generation, VBUS is charged for .5 ms nominal.
0x3: During SRP generation, VBUS is charged for 2 ms nominal.
0x4: During SRP generation, VBUS is charged for 4 ms nominal.
0x5: During SRP generation, VBUS is charged for 6 ms nominal.
0x6: During SRP generation, VBUS is charged for 10 ms nominal.
0x7: During SRP generation, VBUS is charged for 40 ms nominal.
This register is cleared 000 by soft reset or hardware reset.
The current sourcing capabilities of the hardware that drives the SRP
VBUS pulse determines the required duration of the VBUS pulse. The
value chosen must ensure that VBUS rises higher than 2 V within the
selected VBUS pulse duration when attached to an OTG dual-role device.
The value chosen must also ensure that VBUS does not rise higher than
2 V within the selected VBUS pulse duration when attached to a non-OTG
port, such as a USB host port or a downstream port of a USB hub.
SRP_GPUVBUS also controls the duration of a VBUS discharge pulse
when SRP_GPDBVBUS is set to 1. If SRP_GPUVBUS is 0x0, the OTG
controller does not request a VBUS discharge.
The minimum time for SRP signalling completion is (the duration of the
data line pulse defined by SRP_GPDATA) + (2 * VBUS pulse time defined
by SRP_GPUVBUS). Disabling the VBUS discharge does not affect that
minimum time. The interrupt OTG_IRQ_SRC:B_SRP_DONE is generated
upon completion of the entire SRP.
Reserved
SPRU761A
Advertisement
Chapters
Table of Contents
