SAF1760BE/V1,557 NXP Semiconductors, SAF1760BE/V1,557 Datasheet - Page 99

• Manufacturer Part Number: SAF1760BE/V1,557
• Manufacturer: NXP Semiconductors

Specifications of SAF1760BE/V1,557

• Lead Free Status / Rohs Status: Compliant

NXP Semiconductors
SAF1760_1
Product data sheet
17.1.3.2 Hardware retry mechanism
17.2.1 Problem description
17.2.2 Implication
17.2.3 Workaround
17.3.1 Problem description
17.2 Errata added on 2009-04-23
17.3 Errata added on 2009-04-23
Set program register RL = 0000b, NakCnt = 0000b and Cerr = 10b. In this case, interrupt
will not be generated for NAKs and hardware will retry indefinitely, until the device
responds with a data or an ACK.
When at least two USB devices are simultaneously running, it is observed that sometimes
the INT corresponding to one of the USB devices stops occurring. This may be observed
sometimes with USB-to-serial or USB-to-network devices.
The problem is not noticed when only USB mass storage devices are running.
This issue is because of the clearing of the respective Done Map bit on reading the ATL
PTD Done Map register when an INT is generated by another PTD completion, but is not
found set on that read access. In this situation, the respective Done Map bit will remain
reset and no further INT will be asserted, so the data transfer corresponding to that USB
device will stop.
An SOF INT can be used instead of an ATL INT with polling on Done bits. A time-out can
be implemented and if a certain Done bit is never set, verification of the PTD completion
can be done by reading PTD contents (valid bit).
When a low-speed or full-speed device is attached, after some time, the low-speed or
full-speed device suddenly gets disconnected.
The following sequence is observed when the problem occurs:
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The hub class driver detects a change of port status on the problematic port (through
the interrupt endpoint of the hub).
When a Get Port Status command is sent to the problematic port, the Port Enable bit
of the Port Status is cleared. This indicates that a port error has occurred. However,
the current connection status still indicates that a device is present on the port.
The hub driver sends a Port Reset command because of the clearing of the port
enable bit. This causes the disconnection of the attached device and its renumeration.
Before the hub driver detects the port status change, all active transfers on the
problematic port are halted.
Low-speed or full-speed devices connected to other ports are not affected when the
problem occurs.
The problem occurs with low-speed or full-speed devices.
When low-speed or full-speed devices are connected through a high-speed hub, the
problem will not occur.
Rev. 01 — 9 November 2009
Embedded Hi-Speed USB host controller
SAF1760
© NXP B.V. 2009. All rights reserved.
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