ethernet

139 Articles

Want To Learn Ethernet? Write Your Own Darn AVR Bootloader!

October 30, 2018 by 25 Comments

There’s a school of thought that says that to fully understand something, you need to build it yourself. OK, we’re not sure it’s really a school of thought, but that describes a heck of a lot of projects around these parts.

[Tim] aka [mitxela] wrote kiloboot partly because he wanted an Ethernet-capable Trivial File Transfer Protocol (TFTP) bootloader for an ATMega-powered project, and partly because he wanted to understand the Internet. See, if you’re writing a bootloader, you’ve got a limited amount of space and no device drivers or libraries of any kind to fall back on, so you’re going to learn your topic of choice the hard way.

[Tim]’s writeup of the odyssey of cramming so much into 1,000 bytes of code is fantastic. While explaining the Internet takes significantly more space than the Ethernet-capable bootloader itself, we’d wager that you’ll enjoy the compressed overview of UDP, IP, TFTP, and AVR bootloader wizardry as much as we did. And yes, at the end of the day, you’ve also got an Internet-flashable Arduino, which is just what the doctor ordered if you’re building a simple wired IoT device and you get tired of running down to the basement to upload new firmware.

Oh, and in case you hadn’t noticed, cramming an Ethernet bootloader into 1 kB is amazing.

Speaking of bootloaders, if you’re building an I2C slave device out of an ATtiny85¸ you’ll want to check out this bootloader that runs on the tiny chip.

Wiring The ESP-32 To Ethernet

August 19, 2018 by 42 Comments

Since its introduction years ago, the ESP-8266 has taken over the world. It’s the chip inside thousands of different projects, and the basis for dozens of different IoT thingamadoos. The follow-up to the 8266, the ESP-32, is even more capable. It has a ton of peripherals inside, including an Ethernet MAC. What’s that? Yes, it’s possible to put Ethernet on an ESP-32, and give an IoT board PoE. That’s what [Patrick] is doing for his Hackaday Prize project, and it’s an awesome idea.

This build began as you would expect, with an ESP-32 module attached to one side of a board with some breakouts for the GPIOs and a USB to Serial chip. The tricky part here is the PoE part of the Ethernet, which requires MagJack Ethernet connectors, a flyback transformer, and a PoE-PD controller. These were expensive parts, and the design of such a board requires some thinking — you need isolation across the transformer, and proper ground planes for this mess.

There’s something slightly brilliant about using an ESP-32 in a wired configuration. Far too often, we see these modules used as wireless nodes in a sensor net. The battery consumption is significant, and all those makers are adding USB power input to their fancy WiFi sensor nets. If you’re running wires for power anyway, why not add Ethernet and do away with all that mucking around with WiFi setup. It’s a great project, and one of the better entries in this year’s Hackaday Prize.

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Raspberry Pi’s Power Over Ethernet Hardware Sparks False Spying Hubbub

June 1, 2018 by 86 Comments

Have you ever torn open an Ethernet jack? We’d bet the vast majority of readers — even the ones elbow-deep into the hardware world — will answer no. So we applaud the effort in this one, but the conclusion landed way off the mark.

In the last few days, a Tweet showing a Raspberry Pi with its Ethernet socket broken open suggested the little PCB inside it is a hidden bug. With more going on inside than one might expect, the conclusion of the person doing the teardown was that the Raspberry Pi foundation are spying upon us through our Ethernet traffic. That’s just not the case. But we’re still excited about what was found.

Continue reading “Raspberry Pi’s Power Over Ethernet Hardware Sparks False Spying Hubbub” →

RetroModem For The Commodore 64

October 7, 2017 by 17 Comments

Retrocomputers are fun, but ultimately limited in capability compared to modern hardware. One popular pursuit to rectify this is the connection of early home computers to the Internet. To that end, [que] built the Retromodem for the Commodore 64.

The build starts with a case from an Intel 14.4 modem. A little fast for the Commodore 64 era, but anachronism is charming when done tastefully. Inside is an Arduino with an ethernet module to handle the heavy lifting of carrying packets to the outside world.  [que] took the time to wire up status LEDs for the proper vintage look, which really adds something to the project. They switch on and off to indicate the various settings on the modem – it’s great to see in the video below the break the “HS” LED light up when the baud rate is changed to a higher speed.

The project implements most of the Hayes command set, so you can interface with it over a serial terminal just like it’s 1983. [que] doesn’t go into too many details of how it’s all put together, but for the experienced code warrior it’s a project that could be whipped up in a weekend or two. For a more modern take, perhaps you’d like to hook your C64 up over Wifi instead?

Continue reading “RetroModem For The Commodore 64” →

Hackaday Prize Entry: ESP32 Monster And Getting Started Quickly

May 28, 2017 by 19 Comments

Prolific hacker [kodera2t] is working on his own “ESP32 monster board” dev board for the still-newish ESP32 WiFi module. His board has everything: Ethernet, OLED, LiPo, and even CAN-bus. But all that peripheral connectivity is worth nothing if you can’t program the microcontroller to use it.

The Arduino environment for the ESP32 is coming along quite nicely, but it’s not yet fully featured enough to run all of [kodera2t]’s hardware. To take advantage of all that, he needs to use Espressif’s SDK — called the “IoT Development Framework” or IDF for short. In his latest project log, [kodera2t] goes through everything necessary to get the IDF up and compiling on OSX. (It’s strangely similar to the Linux procedure.) Read through the official instructions here, if you want more, but we think [kodera2t] hits all the high points.

While we’re tooting [kodera2t]’s horn, check out his old project — an Arduino shoehorned into an SD card — or watch his alter-ego [Toshiro Kodera] give a serious talk about his day job, engineering radio-frequency meta-materials.

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Go Wireless With This DIY Laser Ethernet Link

April 19, 2017 by 40 Comments

Most of us have Ethernet in our homes today. The real backbones of the Internet though, use no wires at all. Optical fibers carry pulses of light across the land, under the sea, and if you’re lucky, right to your door. [Sven Brauch] decided to create an optical link. He didn’t have any fiber handy, but air will carry laser pulses over short distances quite nicely. The idea of this project is to directly convert ethernet signals to light pulses. For simplicity’s sake, [Sven] limited the bandwidth to one channel, full-duplex, at 10 Megabits per second (Mbps).

The transmit side of the circuit is rather simple. An op-amp circuit acts as a constant current source, biasing the laser diode. The transmit signal from an Ethernet cable is then added in as modulation. This ensures the laser glows brightly for a 1 bit but never shuts completely off for a 0 bit.

The receive side of the circuit starts with a photodiode. The diode is biased up around 35 V, and a transimpedance amplifier (a current to voltage converter) is used to determine if the diode is seeing a 1 or a 0 from the laser. A bit more signal conditioning ensures the output will be a proper differential Ethernet signal.

[Sven] built two identical boards – each with a transmitter and receiver. He tested the circuit by pointing it at a mirror. His Linux box immediately established a link and was reported that there was a duplicate IP address on the network. This was exactly what [Sven] expected. The computer was confused by its own reflection – but the laser and photodiode circuits were working.

Finally, [Sven] connected his PC and a Raspberry Pi to the two circuits. After carefully aligning the lasers on a wooden board, the two machines established a link. Success! (But be aware that a longer distances, more sophisticated alignment mechanisms may be in order.)

Want to know more about fiber and networking? Check out this article about wiring up an older city. You can also use an optical link to control your CNC.

Enabling Ethernet On The ESP32

April 18, 2017 by 28 Comments

The ESP32 is the latest and greatest wonderchip from Espressif. It’s a 32-bit, dual-core chip with WiFi, Bluetooth, and tons of peripherals such as CAN and Ethernet. For most of these peripherals, Espressif already has a few bits of example code, but [Frank Sautter] didn’t like the Ethernet implementation. The ‘stock’ code calls for a TLK110 Ethernet PHY, but that’s an expensive chip when bought in quantity one. A better chip would be the LAN8720, so [Frank] built a board to enable Ethernet on the ESP32 with this chip.

The ESP32 only needs a few components to wire it into an Ethernet network. Just a few resistors, capacitors, and an RJ45 jack will take care of most of the work, but because he’s taking the Ethernet ‘shield’ route, he needs to add his own Ethernet PHY. The Waveshare LAN8720 is the chip for this, but there’s an issue with the pin configuration of the ESP32. GPIO0 on the ESP32 has two functions — the first is pulling it low during startup for serial programming, and the second is the clock input for the EMAC function block. Some bit of circuitry must be devised to allow for both conditions to enable Ethernet on the ESP32.

[Frank]’s solution is to add a few pull-up and pull-down resistors to a breakout board, and use an unused GPIO pin to switch GPIO0 high during startup, but allows a crystal to grab it a bit later. It’s a hack, certainly, but it does allow for some much cheaper chips to be used to give the ESP32 Ethernet.