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UM10503
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© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
688 of 1441
NXP Semiconductors
UM10503
Chapter 25: LPC43xx/LPC43Sxx USB0 Host/Device/OTG controller
The hardware assist consists of the following steps:
1. Hardware resets the OTG controller (writes 1 to the RST bit in USBCMD).
2. Hardware selects the device mode (writes 10 to bits CM[1:0] in USBMODE).
3. Hardware sets the RS bit in USBCMD and enables the necessary interrupts:
–
USB reset enable (URE) - enables interrupt on USB bus reset to device.
–
Sleep enable (SLE) - enables interrupt on device suspend.
–
Port change detect enable (PCE) - enables interrupt on device connect.
When software has enabled this hardware assist, it must not interfere during the transition
and should not write any register in the OTG core until it gets an interrupt from the device
controller signifying that a reset interrupt has occurred or until it has verified that the core
has entered device mode. HCD/DCD must not activate the core soft reset at any time
since this action is performed by hardware. During the transition, the software may see an
interrupt from the disconnect and/or other spurious interrupts (i.e. SOF/etc.) that may or
may not cascade and my be cleared by the soft reset depending on the software response
time.
After the core has entered device mode with help of the hardware assist, the DCD must
ensure that the ENDPTLISTADDR is programmed properly before the host sends a setup
packet. Since the end of the reset duration, which may be initiated quickly (a few
microseconds) after connect, will require at a minimum 50 ms, this is the time for which
the DCD must be ready to accept setup packets after having received notification that the
reset has been detected or simply that the OTG is in device mode which ever occurs first.
If the A-peripheral fails to see a reset after the controller enters device mode and engages
the D+-pull-up, the device controller interrupts the DCD signifying that a suspend has
occurred. This assist will ensure the parameter TA_BDIS_ACON_MAX = 3ms is met.
25.8 Deviations from EHCI standard
For the purposes of a dual-role Host/Device controller with support for On-The-Go
applications, it is necessary to deviate from the EHCI specification. Device operation and
On-The-Go operation is not specified in the EHCI and thus the implementation supported
in this core is specific to the LPC43xx. The host mode operation of the core is near EHCI
compatible with few minor differences documented in this section.
The particulars of the deviations occur in the areas summarized here:
•
Embedded Transaction Translator – Allows direct attachment of FS and LS devices in
host mode without the need for a companion controller.
•
Device operation - In host mode the device operational registers are generally
disabled and thus device mode is mostly transparent when in host mode. However,
there are a couple exceptions documented in the following sections.
•
On-The-Go Operation - This design includes an On-The-Go controller.
25.8.1 Embedded Transaction Translator function
The USB-HS OTG controller supports directly connected full and low speed devices
without requiring a companion controller by including the capabilities of a USB 2.0 high
speed hub transaction translator. Although there is no separate Transaction Translator