USB2524 datasheet(40/58 Pages) MICROCHIP

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USB2524

DS00001588B-page 40

 2013 - 2016 Microchip Technology Inc.

8.0

LED INTERFACE DESCRIPTION

The USB2524 supports 3 different (mutually exclusive) LED modes. USB Mode provides 8 LEDS, which conform to the

USB 2.0 specification functional requirements for Green and Amber LED’s. Basic Host Owner LED Indication mode

uses 8 Single color LED’s to provide user indication of upstream host ownership of the 4 downstream ports. Host Owner

and Downstream Port Speed LED Indication mode uses 8 Dual Color LED’s to provide both a User indication of Down-

stream port ownership, while simultaneously displaying an indication of the speed of the downstream device which is

attached to each of the downstream ports.

8.1

USB Mode

The LED_A[4:1]_N pins are used to provide Green LED, and LED_B[4:1]_N pins are used to provide Amber LED sup-

port as defined in the USB 2.0 specification. The USB Specification defines the LED’s as port and error status indicators

for the downstream ports. Please note that no indication of upstream host ownership is possible in this mode. The pins

are utilized as follows:

LED_A1_N = Port 1 Green

LED_B1_N = Port 1 Amber

LED_A2_N = Port 2 Green

LED_B2_N = Port 2 Amber

LED_A3_N = Port 3 Green

LED_B3_N = Port 3 Amber

LED_A4_N = Port 4 Green

LED_B4_N = Port 4 Amber

8.2

Basic Host Owner LED Indication

All 8 LED pins are used in this mode in conjunction with single-color LEDs to indicate which upstream Host owns each

specific downstream Port. The usage and 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

If a Port is disabled, or is Unassigned, then neither the “A” or “B” LED associated with that port will be asserted.

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 discon-

nected, powered off, etc.

8.3

Host Ownership and Port Speed LED Indication

All 8 LED pins are used in this mode in conjunction with 8 Dual-color LEDs (each LED pair in a single package) to indi-

cate which upstream Host owns each specific downstream Port, as well as the speed that the downstream device is

operating at.

Each dual-color LED provides two separate colors (commonly Green and Red). If each of these separate colors are

pulsed on and off at a rapid rate, a user will see a third color (in this example, Orange). By this means, 4 different “color”

states are possible (Green, Red, Orange, and Off).

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