MDS212 Datasheet, PDF (45/111 Pages) Zarlink Semiconductor Inc – 12-Port 10/100Mbps Ethernet Switch

MDS212
Data Sheet
The port status of the MDS212 is transmitted to an external decoder via a serial output channel. In the MDS212, we
support cascading of this serial output channel between two devices. One MDS212 is configured as the master, this
initiates the start of LED information frames, and serializes information bits. The MDS212 slave repeats the
information sent from the master and appends its own information bits. To cascade these two devices, we will need
to extend the number of LED pins from 3 to 5. Figure 15 shows 2 LED interfaces are cascaded and the connections
between the MDS212s, LED decoder and LED display.
11.1.1 Function Description
The LED interface employs the following signals:
Signal Name
Master Device
Slave Device
LE_CLKO
LE_SYNI
LE_SYNO
LE_DI
LE_DO
Description
LED Clock-Synchronous LED clock provided by the slave device to LED
decoder at the system clock divided by 8(~12.5Mhz).
A synchronous pulse--defines the boundary between frames. The length of
each LED data frame is about 256-bits that shift out by LED_CLK per bit.
A continuous serial stream of data for all status LEDs which repeat once
every frame time.
Table 8 - LED Signal Names and Descriptions
11.1.2 Port Status
In the MDS212, each port consists of 8 different LED status, represented by separate bits:
1. Flow Control
2. Transmitting Data
3. Receiving Data
4. Action (TxD or RxD)
5. Link UP/DOWN
6. Speed
7. Full Duplex/Half Duplex
8. Collision.
In addition to the 12 ports of the MDS212, three extra user-defined status sets may be sent through the LED serial
channel for debugging or other applications, where each user-defined status set is also represented by 8 bits.
11.1.3 LED Interface Time Diagram
The Master needs to shift out (16)*8 status bits periodically((12 port status +4 reserved)*8). Thus, slave needs to
shift out (16)*8 + (16)*8 status bits, which includes the status of the master device and itself.
The status of each port will be sampled by the LED State Machine every 20.5µs, the time period of the frame. That
is, each LED data frame length equals (256)X 80nsec. Each frame is divided into two sub- frames: a master and a
slave sub-frame. Furthermore, each sub-frame is partitioned into 16 slots (12 MAC ports and 4 reserved slots) and
each slot will carry 8 status bits. Figure 16 shows the signal from the slave chip to LED decoder.
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Zarlink Semiconductor Inc.