AT43USB325_05 Datasheet, PDF (83/109 Pages) ATMEL Corporation – Multimedia USB Keyboard Controller with Embedded Hub

AT43USB325
8.4.2
Hub Status Register
In the AT43USB325 overcurrent detection and port power switch control output processing is
done in firmware. The hardware is designed so that various types of hubs are possible just
through firmware modifications.
1. Hub local power status, bits 0 and 2, are optional features and apply to hubs that report
on a global basis. If this feature is not used, both these bits should be programmed to 0.
To use this feature, the firmware needs to know the status of the local power supply,
which requires an input pin and extra internal or external circuitry.
2. Hub overcurrent status, bits 1 and 3, apply to self powered hubs with bus powered SIE
only, or hubs that are programmable as self/bus powered. The firmware should clear
these two bits to 0.
The firmware uses bits 1 and 3 to generate bit 0 of the Hub and Port Status Change Bitmap
which is transmitted through the Hub Endpoint1 Data Register. Bit 0 of this register is a 1 when-
ever bit 1 or 3 of HSTATR is a 1.
8.4.2.1
Hub Status Register – HSTR
Bit
7
6
5
4
3
2
1
$1FC7
–
–
–
–
OVLSC
LPSC
OVI
Read/Write
R
R
R
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
• Bit 7..4 – Reserved
These bits are reserved in the AT43USB325 and will read as zero.
• Bit 3 – OVLSC: Overcurrent Status Change
0 = No change has occurred on Overcurrent Indicator
1 = Overcurrent Indicator has changed
• Bit 2 – LPSC: Hub Local Power Status Change
0 = No change has occurred on Local Power Status
1 = Local Power Status has changed
• Bit 1 – OVI: Overcurrent Indicator
0 = All power operations normal
1 = An overcurrent exist on a hub wide basis
• Bit 0 – LPS: Hub Local Power Status
0 = Local power supply is good
1 = Local power supply is lost (inactive)
0
LPS
HSTR
R/W
0
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3355C–USB–4/05