10BASE-T = 10 Mbit/s Ethernet. 10G/2.5G/1G/100 Ethernet are all backwards compatible so 10BASE-T is the slowest/simplest Ethernet standard that you can implement today and just plug into just about anything.
This is transmit only, so it's pretty much limited to broadcasts (can't do ARP). That's good enough for e.g. sensors.
> 10G/2.5G/1G/100 Ethernet are all backwards compatible
Not always. The physical layers are incredibly different, and while it is true that most 1G devices also support 10M/100M, we found the hard way that some 10G switches and NICs don't.
Can confirm, we have a bunch of $10 switches lying around our million dollar lab because nobody thought to check if the 40Gbit switches can do 100Mbit to talk to Raspberry Pis. Not sure if we're ever pushing 40Gbit but I know we use the hell out of the RPis. Go figure...
> Is a micro-controller able to broadcast through an ethernet port something remarkable?
Many microcontrollers, especially higher-end ones, have built-in dedicated hardware, called peripherals[1], to handle complex and/or high-speed interfaces like Ethernet.
The Pico does not have an Ethernet peripheral, so this project relies on bit-banging[2], a brute-force approach to IO. However, the Pico does have the PIO[3], which is a general-purpose IO peripheral, so it's not pure bit-banging in the traditional sense.
While it's cute, it's not super remarkable. People have done bit-banged HDMI[4] on the Pico for example. However, Ethernet access can be very useful in a Pico project.
"Micro-controller" is a very wide term. Today it is applied to many things that would have been a good desktop computer only 20 years ago. As you surmise it is not at all impressive that they can talk on the network (may have hardware that fully supports current generation wired and wireless networking)
The Pi Pico is quite a simple micro controller, similar to the 1980s hardware that would have actually used 10BASE-T. The impressive bit is it fully software except 3 resistors; rather then having dedicated hardware.
I find remarkable how simple it appears to be. You could take any existing Pico-based board, find two unused pins and solder on those four components. You update the software and suddenly the project is network-connected! For most other micro controllers this would either be impossible (dedicated pin already occupied with another function), or would require installing another PCB.
This is transmit only, so it's pretty much limited to broadcasts (can't do ARP). That's good enough for e.g. sensors.