SMSC USB2524 - Manual (Page 46)

USB MultiSwitch
TM
Hub
Datasheet
Revision 1.91 (08-22-07) 46 SMSC USB2524
DATASHEET
The assignment is as follows:
LED_A1_N = Port 1 Owned By Host A
LED_B1_N = Port 1 Owned By Host B
LED_A2_N = Port 2 Owned By Host A
LED_B2_N = Port 2 Owned By Host B
LED_A3_N = Port 3 Owned By Host A
LED_B3_N = Port 3 Owned By Host B
LED_A4_N = Port 4 Owned By Host A
LED_B4_N = Port 4 Owned By Host B
The Usage is as follows:
LED_Ax_N Driven to Logic Low = Port Owned by Host “A” and is operating at USB LS/FS Speed
LED_Ax_N Driven to Logic High = Port Owned by Host “A” and is operating at USB HS Speed
LED_Ax_N Pulsed @ 1KHz= Port Owned by Host “A” and has nothing attached.
LED_Ax_N is tri-state= LED “A” is off.
LED_Bx_N Driven to Logic Low = Port Owned by Host “B” and is operating at USB LS/FS Speed
LED_Bx_N Driven to Logic High = Port Owned by Host “B” and is operating at USB HS Speed
LED_Bx_N Pulsed @ 1KHz= Port Owned by Host “B” and has nothing attached.
LED_Bx_N is tri-state= LED “B” is off.
If a Port is disabled, or is Unassigned, then neither the “A” or “B” LED associated with that port will
be asserted (i.e. both LED's will be OFF/tri-stated).
Since these LED’s are provided to give an end-user a clear indication of Host Ownership of
downstream ports, they will function when the hub is in suspend, and will indicate Host ownership even
if the applicable assigned Host is disconnected, powered off, etc.
When a downstream device is in suspend (or the Hub is in suspend), connected devices will continue
to reflect the proper LED color for the operational speed the device is enumerated at (i.e, HS will
remain HS, and FS/LS will remain FS/LS) What will change is the 3rd color which represents an
assigned port with no connection, when in suspend the corresponding LED will be off (giving the same
indication as unassigned, while the hub is suspended). This disables the 1khz toggle while the hub
is suspended.