Transparent ESP8266 WiFi-to-Serial Bridge

These days, connecting your microcontroller project to a WiFi network is pretty easy — you connect up an ESP8266 to your microcontroller project and pretend it’s a WiFi modem, using these old-school-style AT commands. But what do you do if you need to flash new code into the microcontroller? You can’t reprogram the micro remotely through the ESP8266 because those stupid AT commands get in the way.

The solution? By flashing the esp-link firmware into your ESP8266, you talk directly to the microcontroller over WiFi as if it were connected by a serial cable: the ESP8266 becomes a totally transparent WiFi-serial bridge. Now, with a serial bootloader and an ESP8266 in Wifi-to-serial bridge mode, you can reflash your microcontroller wirelessly, and then telnet in to interact with and debug the system remotely. Once you’ve fixed the bugs, you can re-flash the microcontroller: all over WiFi, without having to climb up a ladder to reach your IoT attic-temperature sensor.

To flash a connected Arduino, for instance, all you need to do is convince AVRDUDE to use the network instead of a locally-connected USB-serial cable: avrdude -p m328p -c arduino -b 115200 -P net: -U:yourHexFile.hex. The ESP8266 passes the data straight through its TX and RX lines to your microcontroller and everything works as if it were wired.

Configuration to allow the ESP8266 to join your WiFi network takes place on a self-hosted webpage that uses [Sprite_tm]’s esp-httpd standalone server, which makes setup pretty painless. And then after that you can simply telnet to the ESP8266 at port 23 and type away, or do anything else you would with a wired serial connection.

Although the simple bridge mode came first, esp-link looks like it’s growing to be a one-stop shop for all your IoT or microcontroller + WiFi needs. In addition to the serial bridge code, there is also a REST-based microcontroller-to-internet mode and there is bi-directional MQTT support in the wings. We haven’t had a chance to dig into these yet, so if you have, let us know in the comments.

If you want to dig in deeper, head over to [Jeelabs]’ blog for a slightly outdated tour of the project written by the code’s author, [Thorsten von Eicken]. For the most up-to-date development news, follow the very active development of esp-link in this thread on the esp8266 forums.

Radio Receiver or Art? Why not Both?

We’ve heard it said before that you should build things twice. Once to learn how to build it and the second time to build it right. [AA7EE] must agree. He was happy with his homebrew regenerative receiver that he called Sproutie. But he also wanted to build one more and use what he learned to make an even better receiver. The Sproutie Mark II was born.

This isn’t some rip off of an old P-Box kit either. [AA7EE] used a four-device RF stage with FET isolation back to the antenna and a regulated power supply. Plug in coils allow reception on multiple bands ranging from about 3 to 13 MHz. There’s an audio stage with multiple selectable audio filters, and–the best part–a National HRO tuning dial that is a work of art all by itself.

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Mechanical Keyboard Goes BLE

Like many programmers, [Daniel Nugent] loves his old mechanical keyboard (a WASD Code Keyboard). What he didn’t love was the cord. Sure, you can get a modern wireless keyboard, but it won’t be the same as the keyboard you’ve spent so much time with. Armed with a Bluetooth Low Energy (BLE) module, a rechargeable battery and some coding, he kept his keyboard but got rid of the wires.

Although he has some specific handling for the WASD, the code would very likely handle any PS/2 keyboard. The PS/2 interface is a simple synchronous serial port with a single clock and single data line. Handling it with a microcontroller isn’t very difficult.

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Arduino Masters Ham Radio Digital Mode

[jmilldrum] really gets a lot of use out of his Si5351A breakout board. He’s a ham [NT7S], and the Si5351A can generate multiple square waves ranging from 8 kHz to 160 MHz, so it only stands to reason that it is going to be a useful tool for any RF hacker. His most recent exploit is to use the I2C-controllable chip to implement a Fast Simple QSO (FSQ) beacon with an Arduino.

FSQ is a relatively new digital mode that uses a form of low rate FSK to send text and images in a way that is robust under difficult RF propagation. There are 32 different tones used for symbols so common characters only require a single tone. No character takes more than two tones.

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Homebrew Mini-Chumby Blends 3D Printing, ESP8266 and a Touchscreen

We were all despondent when our Chumby’s went dead. And plans to hack at least one of them died when the device quit powering on. [Spiros Papadimitriou] must have missed his too because he’s made a good start at making his own wireless, touchscreen, smart clock.

In all honesty, it isn’t much of a Chumby replacement yet. It has a clock and can control some devices. There’s some hooks to add a weather display that isn’t finished yet. Still, it is a working first step. Of course, anyone can take a Raspberry Pi (or similar), a Wifi dongle, and a touchscreen and do the same thing, right? Maybe, but it is a lot harder to make one you (or your significant other) wants on your nightstand. [Spiros] took a lot of time to design a beautiful 3D printed case.

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Steal This Ham Radio (Technology)

Although I see a lot of wireless projects, I’m always surprised at the lack of diversity in the radio portions of them. I’m a ham radio operator (WD5GNR; I was licensed in 1977) and hams use a variety of radio techniques. If you think hams just use Morse code and voice communications, you are thinking of your grandfather’s ham radio. Modern hams have gone digital and communicate via satellites, video, and many different digital techniques that could easily have applicability to different wireless projects.

Of course, Morse code may have been one of the first digital modes. But hams have used teletype, FAX, and other digital modes for years. Now with PCs and soundcards in common use, hams have been on the forefront of devising sophisticated digital radio techniques.

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Hams Talk Digital

Morse code qualifies as a digital mode, although organic brains are somewhat better at copying it than electronic ones. Ham radio operators that did “phone” (ham-talk for voice) started out with AM modulation. Sometime after World War II, there was widespread adoption of single side band or SSB. SSB takes up less bandwidth and is more reliable than AM modulation. On the digital side, hams turned to different and more sophisticated digital transmission types with computers pushing bandwidth down and reliability up. However, a recent trend has been to encode voice over ham radio–sort of VoIP with radio instead of Ethernet–using an open source program called freedv.

[AA6E] made a very informative video where he carries on a QSO (a conversation) with a distant station using freedv. What makes it interesting, is towards the end when the two stations switch to regular SSB. The difference is dramatic and really points out how even with less bandwidth (roughly 3 kHz for SSB vs 1.25 kHz), the digital mode is superior. The freedv software (available for Windows or Linux) compresses audio to 700-1600 bits per second and spreads it over 16 QPSK signals.

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