Microcontrollers

2336 Articles

Arduino Library Brings Rtl_433 To The ESP32

January 13, 2023 by 10 Comments

If you have an RTL-SDR compatible radio there’s an excellent chance you’ve heard of the rtl_433 project, which lets you receive and decode signals from an ever-expanding list of supported devices in the ISM radio bands. It’s an incredibly useful piece of software, but the fact that it requires an external software defined radio and a full-fledged computer to run dictated the sort of projects it could realistically be used for.

But thanks to the rtl_433_ESP Arduino library developed by [NorthernMan54], we’re now able to pack that functionality into a much smaller package. All you need is an ESP32 microcontroller and a CC1101 or SX127X transceiver module. If you’re looking for a turn-key hardware platform, the documentation notes the LILYGO LoRa32 V2 board includes the required hardware, plus adds a handy OLED display and microSD slot. It should be noted that the range of these radios don’t compare particularly well to a full-size RTL-SDR device, but that probably won’t come as much of a surprise. Continue reading “Arduino Library Brings Rtl_433 To The ESP32” →

A Simple Serial Display

January 9, 2023 by 11 Comments

Often with more “modern” complex protocols involving handshaking, token exchanges, and all the other hoops and whistles accompanying them, we forget how useful and powerful serial can be. In what might be a wonderful tribute to that, [Davide Gironi] created a simple AVR-powered 16-digit serial display.

It can display two numbers, and that’s it. A MAX7219 drives the display, and the brains are an ATmega8. It’s straightforward to send new values: a start byte, a CRC, the data to display, and an end byte. A CP2102 provides a UART to USB interface to connect to a host. An EEPROM helps it remember the last numbers shown. It supports positive, negative, and floating-point numbers.

This is a beautiful example of doing one thing and doing it well. The design is simple and allows it to be used for anything. You can show the current stock market price, the time for the next two trains for your commute, or whatever else you can think of. [Davide] included a schematic, code, and a 3d printed enclosure.

Perhaps the idea could be combined with a clever design for a single-motor seven-segment display.

Continue reading “A Simple Serial Display” →

Low-Cost 433 MHz Door Sensors Get Open Firmware

January 8, 2023 by 38 Comments

It’s an unfortunate reality these days that if you see a cheap piece of consumer electronics, there’s a good chance its only cheap because it’s designed to lock you into some ecosystem where you’ll either end up paying a subscription, or worse, have your personal information sold behind your back. One of the best tools we have against these sort of anti-consumer practices is the development of open source firmware replacements that put control of the device into the hands of the community, rather than a corporation.

Now, thanks to the work of [Jonathan Armstrong] we have such a firmware for the 433 MHz magnetic door and window sensors that you can pick up on AliExpress for $4 USD a piece. The new firmware not only ensures you can use these sensors with a wide array of receivers, but adds a number of new features over their stock configuration. Continue reading “Low-Cost 433 MHz Door Sensors Get Open Firmware” →

Wireless CNC Pendant Implemented With ESP-NOW

January 7, 2023 by 6 Comments

As a fervent fan of twiddly and twirly widgets and tactile buttons in a device’s user interface, [Steve M Potter] created a remote control (pendant) for his CNC machine, which he explains in a recent video that’s also linked down below. In addition to all the tactile goodness, what is perhaps most interesting about this controller is that it uses Espressif’s ESP-NOW protocol. This still uses the same 2.4 GHz as WiFi would, but uses a system more akin to the pairing of a wireless mouse or keyboard.

Advantages of ESP-NOW include the lower power usage, longer range, no requirement for a router and WiFi SSID & password. As far as latency goes, [Steve] measured a round-trip latency of 2.4 ms, which is fast enough for this purpose. Since it does control a potentially dangerous machine, all transmissions are acknowledged and re-transmitted at higher power if needed.

The lower power usage means that the pendant will last a lot longer on a single charge from the 18650 Li-ion cell, while ESP-NOW’s fixed address pairing saves time when turning the pendant on. Meanwhile, on the CNC side, another ESP32 acts as the receiving end for commands, although theoretically an ESP8266 could be used as well, if size or power was a concern there.

As for the transparent enclosure? It’s to make it easier to show it off to interested folk, apparently.

Continue reading “Wireless CNC Pendant Implemented With ESP-NOW” →

New Part Day: ESP32-P4 Espressif RISC-V Powerhouse

January 7, 2023 by 63 Comments

It seems every day there’s a new microcontroller announcement for which the manufacturer is keen to secure your eyeballs. Today it’s the turn of Espressif, whose new part is the ESP32-P4, which despite being another confusingly named ESP32, is a high-performance addition to their RISC-V line-up.

On board are dual-core 400 MHz and a single-core low power 40 MHz RISC-V processors, and an impressive array of hardware peripherals including display and camera interfaces and a hardware JPEG codec alongside the ones you’d expect from an ESP32 part. It’s got a whopping 768 KB of on-chip SRAM as well as 8 K of very fast cache RAM for intensive operations.

So after the blurb, what’s in it for us? It’s inevitable that the RISC-V parts will over time displace the Tensilica parts over time, so we’ll be seeing more on this processor in upcoming Hackaday projects. We expect in particular for this one to be seized upon by badge developers, who are intent on pushing extra functionality out of their parts.So we look forward to seeing the inevitable modules with this chip on board, and putting them through their paces.

Thanks [Renze] for the tip.

A small brown PCB with various components on it. There is a headphone cable and DC barrel connector cable coming out of it.

Put Your Serial Port On The Web

January 7, 2023 by 37 Comments

Today, everything from your computer to your dryer has wireless communications built in, but devices weren’t always so unencumbered by wires. What to do when you have a legacy serial device, but no serial port on the computer you want to connect? [vahidyou] designed a wireless serial dongle to solve this conundrum.

Faced with a CNC that took instructions over serial port, and not wanting to deal with the cabling involved in a serial to USB adapter, [vahidyou] turned to an ESP8266 to let his computer and device talk wirelessly. The hand-made PCB connects via a 3.5 mm headphone jack to DB9 adapter which he describes in another article. While [vahidyou] did write a small Windows program for managing the device, it is probably easier to simply access it in a web browser from any device you have handy.

Want to see another wireless serial port application? This Palm Portable Keyboard Bluetooth dongle will let you type in comfort on the go, or you can use a PiModem to get your retrocomputer online!

PCB Gets Weighty Assignment

January 5, 2023 by 9 Comments

[Curious Scientist] tried building an integrated strain gauge on a PCB, but ran into problems. Mainly, the low resistance of the traces didn’t show enough change under strain to measure easily. Even placing a proper strain gauge on the PCB had limitations. His new design uses a bridge design to make the change in the gauges usefully large. You can see a video of the project below.

Bridging strain gauges isn’t a new idea. However, the novelty of this design is that the PCB has cantilever beams that facilitate the weighing. Standoffs mount a plate to the beams so that weight on the plate cause deformation on the beam that the strain gauges can measure.

Continue reading “PCB Gets Weighty Assignment” →