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Comment by francisduvivier | Hacker News Reader

Sooo, with this you can send ethernet packets from a RPI pico? I wonder at which speeds with this setup only using 2 GPIO's.

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Using the PIO you can get some serious speed out of it. Someone made an arbitrary waveform generator[1] reaching 125Msps stock, for example. But you can overclock[2] the Pico up to 420MHz apparently so maybe you can get even more, though not sure if the GPIO drivers can handle that though.

[1]: https://www.instructables.com/Arbitrary-Wave-Generator-With-...

[2]: https://www.youtube.com/watch?v=G2BuoFNLoDM

If you want to communicate with standard Ethernet gear, that would be either 10Mbit/s exactly (10BASE-T standard) and 100Mbit/s exactly (100BASE-TX standard).

OP implemented 10BASE-T here. Next step up is 100BASE-TX, which nobody did in software/bit-bang as of yet, as far as I'm aware - part of the reason it's fairly large jump in complexity. Namely, you'd need 3 analog voltage levels, as well as pretty hairy digital scrambling/encoding, to output 100BASE-TX. RPi-pico might just be able to eek that out with few external resistors and enough elbow grease.

Other reason nobody bothered with bit-bang 100BASE-TX - virtually all switches will happily down-negotiage to 10BASE-T, which gives you ~1.2MB/s, and that's plenty fast enough for a microcontroller with mere kilobytes of RAM.

10Mb/s - it's 10BASE-T

The fact that it links up at 10BASE-T does not mean that it can send at wire rate.

That's exactly what it means. But if you didn't know that you can look at the last oscilloscope screenshot; as you can see, it's set to 200 nanoseconds per division, and it's pumping out bit transitions quite precisely every 50 nanoseconds, and 10BaseT uses Manchester encoding, so that gives you 10 megabits per second.

I think GP might mean what sort of data throughput would be achievable, but that's also trivially 10Mbps with suitably trivial data, and sending easier than non->/dev/null rx.

Really more a question of what you try to make it do with the link, but it would be fun to see it do some very basic routing/firewalli g for example.

He'll have to get reception working first :)

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