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LAN8720 ETH PHY Activity LED indicating only inbound traffic?

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Yansi:
Hello,

just started tinkering with ETHernet, now completed my first hello world using a LAN8720 ETH PHY (Datasheet).

What I found interesting (and to be honest, very annoying) is that the activity LED blinks only on inbound (receive) traffic. When I for example send a packet every second, the LED does not blink, stays lit.

I think this is beyond stupid, as if I wanted to use the PHY in a device, for example a UDP streaming device, that produces 99% traffic only outbound (transmit), the LED would not indicate absolutely anything.

Datasheet of the PHY seems to confirm this stupid behavior of the LED: Section 3.8, quoute: "The LED1 output is driven active whenever the device detects a valid link, and blinks when CRS is active (high) indicat-ing activity"

Why is that? Is it normal the link/activity LED blinks only on received data (CRS, carrier sense)?

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