Microcontrollers

2243 Articles

This Arduino Debugger Uses The CH552

September 11, 2023 by 16 Comments

One of the things missing from the “classic” Arduino experience is debugging. That’s a shame, too, because the chips used have that capability. However, the latest IDE has the ability to work with external debuggers and if you want to get started with a classic ATMega Arduino, [deqing] shows you how to get started with a cheap CH552 8-bit USB microcontroller board as the debugging dongle.

The CH552 board in question is a good choice, primarily because it is dirt cheap. There are design files on GitHub (and the firmware), but you could probably pull the same trick with any of the available CH552 breakout boards.

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Cheap LCD Uses USB Serial

September 11, 2023 by 19 Comments

Browsing the Asian marketplaces online is always an experience. Sometimes, you see things at ridiculously low prices. Other times, you see things and wonder who is buying them and why — a shrimp pillow? But sometimes, you see something that probably could have a more useful purpose than the proposed use case.

That’s the case with the glut of “smart displays” you can find at very low prices. Ostensibly, these are being sold as system monitors. A business-card-sized LCD hooks up via USB and shows your CPU speed, temperature, and so on. Of course, this requires sketchy Windows software. I don’t run Windows, and if I did, I wouldn’t be keen to put some strange service on just so I could see tiny displays of my system information. But a 3.5-inch IPS LCD screen for $15 or less probably has some other uses. But how to drive it? Turns out, it is easier than you think and the hardware looks reasonably hackable, too.

Like a lot of this cheap stuff, these screens are sold under a variety of names, and apparently, there are some subtle differences. Two of the main makers of these screens are Turing and XuanFang, although you rarely see those names in the online listings. As you might expect, though, someone has reverse-engineered the protocol, and there is Python software that will replace the stock Windows software the devices use. Even better, there is an example of using the library for your own purposes.

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Open Deck Is Your Window To Shortcuts

September 10, 2023 by 11 Comments

Once in a while, we see projects that could easily pass for commercial products. This is one of those projects: a (surprisingly) low-cost DIY macro pad from [Josh R] that was designed to be a cheaper alternative to the various stream decks out there. Between the carbon fiber top plate and the crystal-clear acrylic keycaps, this is quite the elegant solution.

This lovely little macro pad is built around the ESP8266, specifically the WEMOS D1 Mini V4. However, the most vital part to get right is the screen, which must be a 128 x 160 TFT display in order to line up with the 3D printed frame that divides it into fourths. Custom parts like the acrylic keycaps and the carbon fiber top plate are available on Tindie if you don’t have access to a CNC.

Operationally, Open Deck has a nice-looking GUI. Once programmed, each shortcut is capable of having three beneath it, with the fourth button reserved for Home. Be sure to check out the extremely satisfying build video after the break.

Want a stream deck, but don’t want to build it? Just dig up an old phone or tablet.

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How Small Can The ESP32 Get?

September 7, 2023 by 25 Comments

At its core, the ESP32 chip is not much more than an integrated circuit, a huge mass of transistors sealed inside an epoxy resin package with some leads. Of course, most of us won’t buy discrete ESP32 chips with no support circuitry since it’s typically easier and often not that much more expensive to get them paired with development boards of some type for easy access to things like USB and GPIO. But these tiny chips need little in the way of support to get up and running as [Paul] demonstrates with this tiny ESP32 board.

The project started as a challenge for [Paul] to build the smallest ESP32 that would still function. That means carving away nearly everything normally found accompanying one of these chips. There is no charging circuitry, only one of the GPIO pins is accessible, and it even foregoes the WiFi antennas which eliminates the major reason most people would reach for this chip in the first place. But at this form factor even without wireless capabilities it still blows other chips of this stature, like the ATtiny series, out of the water.

Even though [Paul] built it as a challenge, it goes a long way to demonstrate what’s really needed to get one of these chips up and running properly. And plenty of projects don’t need a ton of I/O or Wi-Fi either, so presuming these individual chips can be found cheaply and boards produced for various projects its an excellent way to minimize size and perhaps even power requirements. You can make these boards even smaller than a USB-A connector if you want to take this process even further, too.

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Streaming Video From An ESP32

September 5, 2023 by 11 Comments

The ESP32, while first thought to be little more than a way of adding wireless capabilities to other microcontrollers, has quickly replaced many of them with its ability to be programmed as its own platform rather than simply an accessory. This also paved the way for accessories of its own, such as various sensors and even a camera. This guide goes over taking the input from the camera and streaming it out over the network to multiple browsers.

On the server side of things, the ESP32 and its attached camera are set up with MQTT, a lightweight communications protocol which uses a publish/subscribe model to send information. The ESP32 is configured to publish its images only, but not subscribe to any other nodes. On the client side, the browser runs a JavaScript program which is able to gather these images and stitch them together into a video.

This can be quite a bit of data to send out over the ESP32’s compact hardware, so there are some tips and tricks for getting more out of these little devices, including using an external antenna for better Wi-Fi signal, or omitting it entirely in favor of Ethernet. As far as getting a lot out of a tiny microcontroller, though, leveraging MQTT really helps the ESP32 go a long way. These chips have come along way since they were first introduced; they’re powerful enough to act as 8-bit gaming consoles too.

Thanks to [Surfskidude] for the tip!

Accurate Cycle Counting On RP2040 MicroPython

August 26, 2023 by 14 Comments

The RP2040 is a gorgeous little chip with a well-defined datasheet and a fantastic price tag. Two SDKs are even offered: one based on C and the other MicroPython. More experienced MCU wranglers will likely reach for the C variant, but Python does bring a certain speed when banging out a quick project or proof of concept. Perhaps that’s why [Jeremy Bentham] ported his RP2040-based vehicle speedometer to MicroPython.

The two things that make that difficult are that MicroPython tries to be pretty generic, which means some hackery is needed to talk to the low-level hardware, and that MicroPython doesn’t have a reputation for accurate cycle counting. In this case, the low-level hardware is the PWM peripheral. He details the underlying mechanism in more detail in the C version. On the RP2040, the PWM module can count pulse edges on an input. However, you must start and stop it accurately to calculate the amount of time captured. From there, it’s just edges divided by time. For this, the DMA system is pulled in. A DMA request can be triggered once the PWM counter rolls over. The other PWM channel acts as a timer, and when the timer expires, the DMA request turns off the counter. This works great for fast signals but is inaccurate for slow signals (below 1kHz). So, a reciprocal or time-interval system is included, where the time between edges is captured instead of counting the number of edges in a period,

What’s interesting here is how the hardware details are wrapped neatly into pico_devices.py. The uctypes module from MicroPython allows access to MMIO devices such as DMA and PWM. The code is available on GitHub. Of course, [Jeremy] is no stranger to hacking around on the RP2040, as he has previously rolled his own WiFi driver for the Pico W.

Patching Together Logic Gates

August 25, 2023 by 14 Comments

The digital world offers many advantages over its analog relatives, the use of boolean logic among them. Some of the functions, like NOT, OR, and AND are fairly straightforward and line up nicely with their linguistic counterparts. Others are more elusive, like XOR and NAND. For those just getting their start in digital logic, this teaching tool allows different logic gates to be wired together with patch cables.

While [David] first thought to use 74-series logic circuits directly, a much more versatile solution was to use configurable custom logic — a feature found in AVR DA-series microcontrollers that allows for the creation of custom logic circuits without the need for external hardware or complex programming. He went with an ATmega4809 which is capable of supporting twelve gates which are depicted graphically on the board, where the patch cables can be connected between inputs and outputs from a set of switches on the left to another set of LEDs on the right. The microcontroller continually polls for connections, applies the correct logic via a lookup table, and lights the appropriate LED.

Even with only twelve gates, the amount of real-world analogs that can be created with this teaching tool are numerous and varied, from simple things like displaying traffic light patterns in the correct order to implementing a binary adder. It’s an excellent way to get started in digital logic or understanding gates, and much simpler than dealing with 74-series chips on a breadboard like many of us might have done, but those logic chips can be powerful tools to have on hand even in the modern world of microcontrollers.