5238-DS03-405-R datasheet(26/76 Pages) BOARDCOM

26 / 76 page

BCM5238

Advance Data Sheet

1/31/03

Broa d c om Co rp o r a t i o n

Page 18

LED Display Output Modes

Document

5238-DS03-405-R

Section 5: L E D Di sp lay Out put Mod e s

DESCRIPTION

The BCM5238 offers a rich set of LED display outputs through serial, parallel, and extended parallel LED modes. There are

two serial LED modes available, serial LED mode and low-cost serial LED mode. Serial LED modes are selected by

hardware only during power-on reset.

SERIAL LED MODE

Serial LED mode is enabled only by holding the SERIAL_EN pin high and LC_SER_EN pin low during power-on reset. If

serial LED mode is enabled, low-cost serial LED mode is disabled. In serial LED mode the BCM5238 sources a serial data

stream, the associated clock, and a framing signal as follows:

•

a serial data stream, SLED_DO, which is an active low bit stream containing 48 bits per frame.

•

a serial data clock, SLED_CLK, which runs at approximately 2 MHz to clock out SLED_DO on the falling edge of this

clock. SLED_DO is valid on the rising edge of this clock.

•

a framing pulse, SFRAME, which is an active high pulse occurring once every 48 SLED_DO bit times. SFRAME goes

high coincident with bit 0 of port 1.

The BCM5238 provides two different serial LED streams, described below:

•

When the serial LED mode is enabled by hardware, and no further action is taken, the LED stream is selected for

SLED_DO (as shown in Table 5) depending on the values of bit 14 and 15 of MII register 1Ah. The data stream contains

bit 0 to bit 5 for port 1, bit 0 to bit 5 for port 2, ..., bit 0 to bit 5 for port 8.

NOTE—A global interrupt indicates an interrupt from any of the eight PHY as if they were ORed together. A port interrupt

is provided on a per PHY basis.

•

If MII shadow register 1Ah (of PHY 2 of 8) bit 9, Serial LED Program Enable, is set to a 1, then the serial LED stream is

selected by the serial bank select bits as specified in Table 6, Table 7, Table 8, Table 9, Table 10 and Table 11. LED

stream will contain bank 1 output for port 1 through port 8, bank 2 output for port 1 through port 8, ..., bank 6 output for

port 1 through port 8.

Table 5: Serial LED Mode Bit Framing

Serial bit 5

Serial bit 4

Serial bit 3

Serial bit 2

Serial bit 1

Serial bit 0

Bit 15 = 0

Bit 14 = 0

FDX

COL

Speed100

Link

Transmit

Receive

Bit 15 = 0

Bit 14 = 1

FDX

Global

Interrupt

Speed100

Link

Port

Interrupt

Activity

Bit 15 = 1

Bit 14 = 0

FDX

COL

Speed100

Link

FDX

Activity

Bit 15 = 1

Bit 14 = 1

FDX

Global

Interrupt

Speed100

Link

FDX

Activity

5238-DS03-405-R Datasheet(PDF) 26 Page - Broadcom Corporation.

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