10BASE-T using Raspberry Pi Pico with 2 GPIO pins

A word of caution: this has been done with other uControllers in the past; nothing wrong with it from a functional point of view, but be aware that the lack of transformers means the boards i/o pins aren't insulated from whatever it's connected to them; any wrong connection by mistake or static charges in case of a long cable could damage the chip forever. The best and safest use i can imagine of a transformerless arrangement would be a cluster of Pi Picos all mounted on a backplane containing a Ethernet switch chip; in that situation they would share the same power supply and ground so a simple level translation where necessary would be enough, and probably a total of two wires could be used for transmission and receive since balanced signals wouldn't be needed anymore.

I read the this as 10GBASE-T and for a brief moment in time my whole world turned upside down.

Oh wow, this is was earlier in development than I was expecting. Literally just banging out the bits on the wire for a UDP packet without any underlying protocol support. No CSMA/CA. No ARP. No autonegotiation. Can't even receive. Just enough support to calculate the checksums and do the Manchester encoding before clocking the bits out on the wire.

cnlohr did something similar with an ATTiny85:<p><a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=mwcvElQS-hM" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=mwcvElQS-hM</a> <a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=m4f4OzEyueg&amp;t=0s" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=m4f4OzEyueg&amp;t=0s</a><p>Pretty amazing!

A similar thing for the Forth chips produced by Chuck More and colleagues: <a href="https:&#x2F;&#x2F;www.greenarraychips.com&#x2F;home&#x2F;documents&#x2F;greg&#x2F;AN007-141112-10BASET.pdf" rel="nofollow">https:&#x2F;&#x2F;www.greenarraychips.com&#x2F;home&#x2F;documents&#x2F;greg&#x2F;AN007-14...</a>

Should be able to run CANbus also, here we go, someone did it:<p><a href="https:&#x2F;&#x2F;github.com&#x2F;kentindell&#x2F;canhack" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;kentindell&#x2F;canhack</a>

This is also possible using GPIOs on an FPGA as well. Have a look over at FPGA4Fun: <a href="https:&#x2F;&#x2F;www.fpga4fun.com&#x2F;10BASE-T.html" rel="nofollow">https:&#x2F;&#x2F;www.fpga4fun.com&#x2F;10BASE-T.html</a> 10base-T is such a simple protocol, and implementing it is a good way to learn many of the physicaly layer fundamentals of Ethernet.

The funniest Ethernet system I&#x27;ve seen is that used in dataprobe&#x27;s &quot;iBoot&quot; remote power switch. These used 8051 microcontroller (the classic 40-pin DIP) connected to an ISA-bus FIFO-based 10&#x2F;100 Ethernet chip using GPIOs. The FIFO saves you since the 8051 doesn&#x27;t have to keep up with the line rate (one whole packet has to fit in the FIFO).<p>But I know these devices fail when the network is chatty- like if you have spanning-tree enabled.<p>The iBoot has a simple web interface. Somebody wrote an entire network stack for 8051..

RP2040 is an amazing MCU, I&#x27;m unaware of any other similar MCU has a programmable PIO module.<p>Based on the Ethernet and previous HDMI work done to this chip, I&#x27;m to write my own I3C master&#x2F;slave on it soon, should be doable.

Can someone explain to me what I&#x27;m looking at it?

Is &quot;register&quot; instead of &quot;resistor&quot; just a typo, or is that word really used in this context?

The other repository seems more interesting (can someone translate?) <a href="https:&#x2F;&#x2F;github.com&#x2F;kingyoPiyo&#x2F;RasPico_SHIBAKI_Board" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;kingyoPiyo&#x2F;RasPico_SHIBAKI_Board</a><p>This seems to be SFP with Raspberry Pico.

Pretty neat. I wonder how much noise those lines can handle.

The transformer-coupling of Ethernet isn&#x27;t a trivial fact.<p>When building precision instrumentation, I was extremely happy to learn about this from one of our old-timers who had been working on systems since the days of the VAX.<p>You need not worry about DC ground-loops with Ethernet.<p>When I saw the post-title, I thought, &quot;oh, no, what about the transformer-coupling?&quot;. Was very happy to see a simple technique outlined in the article.

Sooo, with this you can send ethernet packets from a RPI pico? I wonder at which speeds with this setup only using 2 GPIO&#x27;s.

LWIP [1] could be used for this. You&#x27;d just need to implement I&#x2F;O.<p>[1]: <a href="https:&#x2F;&#x2F;www.nongnu.org&#x2F;lwip&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.nongnu.org&#x2F;lwip&#x2F;</a>

Was hoping that said 10GB - need a couple 10GB devices for load testing a network lab if anyone has any cheap suggestions :)