Hiya fellow engineers and makers!

Presenting μArt, an isolated USB to UART-TTL adapter that is truly versatile, safe, and dependable. You can use it almost anywhere you need to connect a UART to your computer’s USB port, regardless of voltage levels, electric potentials, and communication speed, and whether it is used for data exchange or for programming Arduinos, ESPs, or other devices. At the same time, μArt is robust and tolerates common user mistakes without being damaged or causing damage to other hardware. μArt was created so that you can finally replace your collection of UART converters with a single, high-quality tool.

Overview

It is no secret that there are many UART adapters on the market. So, you might ask, what’s the point of creating yet another one? The unfortunate reality is that despite the general usefulness of such devices, none of them seem able to solve the associated problems in a general and reliable way. Consequently, most engineers have a collection of them lying around: some just to cover the needed voltage ranges, others to add handshake and firmware-flashing pins, maybe another one that is isolated (or a separate USB isolator, which tends to be expensive), and a few to work around quirks of the others or to function as backups.

Another problem is that most of the existing solutions have quality problems. Pins can easily float, ruining application state, the slightest mistakes will easily damage expensive connected devices, the adapters often fail and require replacement, and there are latchups, freezes, data errors - as an experienced engineer or maker, you have most likely seen at least some of these phenomena.

This is where the μArt comes in. It was made to address both problems above: covering all use cases with a single device, and offering a reliable and robust solution that you can just trust to work right. The μArt has all the pins and features to enable various applications, protections to withstand or even prevent faults, means to preserve signal integrity, and measures to improve usability.

The μArt is based on the principle that a UART adapter is your tool, and you should be able trust your tools to get the job done.

Who Needs It and Why?

USB-UART converters are ubiquitous and often used through many phases of a product’s development and lifecycle. They are used during initial board bringup, for debugging and development, for flashing firmware, for exchanging operational data, for controlling peripherals, as service ports in the field, or as diagnostic interfaces during analysis. If you work or hack in the electronics engineering, computer engineering, or embedded systems fields, it is safe to say that a UART adapter is one of your basic tools.

The μArt addresses typical problems of UART boards that plague both new and experienced engineers. Industry professionals will value being able to depend on the μArt and being able to focus on their work without having to second-guess their tool. Hobbyists and students, who can make mistakes more easily, will like that the μArt isolates faults and prevents damage to surrounding equipment. Regardless of which group you belong to, you will appreciate the ease of using a single device for all related tasks, and that the μArt incorporates features found only in the best of the alternatives but now makes them available for all use-cases. The μArt will save time, money, hardware, and nerves.

Ideal for Makers too

During design of the μArt, we made sure that the needs of some of the largest prototyping communities were fulfilled, so it is also an ideal companion for Raspberry, Arduino, and Espressif fans.

In fact, μArt is possibly the first adapter to include adequate port protection so that misconnected wires can’t damage the Raspberry’s sensitive pins.

AVRs often utilize clocks that are ill-suited to generating standard UART baudrates. This results in UART communication that is picky about the converter in use, more likely to exhibit data errors, or just simply slow. The μArt supports non-standard and custom baudrates (such as 128000) so that you can use a fast and reliable setting for your MCU.

Some Arduino boards do not have a built-in USB-UART converter, in which case you have to rely your own. Programming such boards can present a challenge since not all adapters possess the necessary pins (DTR) for an automatic flashing process. Users of some ESP modules are in a similar situation but with a different set of needed signals (DTR, RTS). The μArt incorporates the necessary pins for both kinds of boards, and enables fast and fully automatic flashing from the Arduino IDE.

The μArt in action.

Key Features

• Universal TTL-UART: 1.8 - 5.4 V, up to 3M speed, standard & non-standard baudrates, pins for handshaking and flashing various MCU families, wide OS-support
• Reliable: Galvanic isolation, integrated pullups, signal- and power-filters
• Robust: Over-current protection, reverse-polarity protection, ESD protection, mechanical protection
• Feature packed: Voltage-autosensing, LEDs, GPIOs, software-configurable
• Compact: 58 x 33 x 14 mm, 16 g

Detailed Description

The μArt replaces all your other UART converters for TTL signals with a single device that is at the same time more reliable and compatible. These properties are the combined result of the following features and design decisions.

• Wide working voltage of 1.8 to 5.4 V, making it suitable for most projects, be it single-board computers, microcontrollers, FPGAs, or low-power electronics.
• RXD, TXD, DTR, RTS, and CTS. Usable not just for basic communication, but also for flashing various modules from Espressif and multiple Arduinos such as the Pro Mini, Fio, or Arduino Pro. Hardware handshaking allows for reliable high-speed UART.
• Non-standard baudrate support, so that you can use it with standard-clocked microcontrollers and still have a low error-rate.
• Up to 3 Mbaud transfer speed, the highest in the industry. For example, this is enough bandwidth to stream uncompressed high-quality stereo audio.
• Complete galvanic isolation, even for mains-level and higher voltages. Electrical current cannot flow between your computer and the other board. This spells safety for you and your computer, while also helping to keep noise levels down.
• Reverse polarity protection. The converter will survive even if you mix up the power pins.
• Over-current protection on IO pins. Made a false IO connection by mistake? Don’t worry, the μArt and your other board are both safe.
• Pullups on all inputs, so that disconnected pins don’t cause funny things like garbage random input, a ruined terminal app, or corrupt application state.
• Judicious filtering. Each IC in the converter is decoupled using multiple capacitors, both locally and in bulk. The USB signals and power are filtered, and sensitive pins are protected with RC networks.

The μArt on the inside.

• Multi-level ESD protection for all interfaces. ESD damage is tricky because things can seem to work for a while after an ESD event, and you don’t need visible sparks to have it.
• Voltage auto-sensing, meaning the converter will automatically use the correct voltage levels for UART communication. No more setting jumpers or “Which of these five converter boards was the one for 3V3?”.
• Cross-platform support, with readily available and mature drivers for Windows, Linux, MacOS, and more*.
• Suitable for communicating with low-noise circuits, supported by the filters, the isolation, and careful layout.
• GPIO pins that you can control directly over USB, parallel to the UART lines. They can also be reconfigured in software for alternate functions (for example, TXDEN for RS-485).
• Four LEDs, each of different color to make them immediately distinguishable. One lights up if power is connected, two indicate RX/TX activity, while the last one is connected to a GPIO, giving you visual feedback about its state without special software on the host computer.
• Four-wall shrouded header protects against ESD from fingers and from shorts by dangling wires.
• Custom-designed case, professional and ergonomic, giving both mechanical and electrical protection, and a cool transparent-translucent look.

*Note: GPIOs are only supported on Windows and Linux at the moment.

Enclosure

The μArt comes in a custom-designed plastic case by default. It is made to fit the product perfectly, and provides mechanical protection while at the same time adding to the electrical protections. It is a mixture of semi-transparent and crystal clear surface design that makes labels and LEDs on the board readable. Top labels* are formed on the case itself directly out of the case’s material, which means they will not come or rub off. The enclosure’s top and bottom half mate with a snap-in mechanism which can be pulled apart, giving you direct access to the electronics in case you want to hack it (not that you’ll need to).

The μArt injection molded.

The μArt is compact.

*Note: On prototype cases shown in pictures, the pin and LED labels are harder to read than on the injection molded cases. This is due to limitations in the prototype manufacturing process and will not affect units shipped to backers.

Cable Bundle

If you choose to also pledge for a cable bundle, you’ll get an assortment of cables to make sure you have everything you need to start using the μArt. In addition to the device with its case, the following will also be included:

• A high-quality Micro USB cable by KabelDirekt
• A split "squid" cable that mates with the μArt using a single connector (female ends)
• A ribbon jumper cable (male ends)

μArt Cable Bundle.

Comparisons

Due to the many products and copy-cats on the market, it is impractical to include them all in any comparison. We firmly believe, though, that based on our experience and research the μArt is the most comprehensive and reliable solution as of today. Below table shows some of the most easily accessible and better known (not hand-picked) devices compared to ours.

Manufacturing Plan

There will be as many units manufactured as there are pledges, but at a minimum 250 units. This is the minimum quantity needed to keep prices reasonable. Collected funds will go to manufacturing the electronics, injection molding the cases, and of course shipping all the units. Pledge levels are based on specific manufacturer quotes, and there is a small buffer (<10%) to compensate for potential price changes during the campaign.

The electronics will be assembled in Hungary, Europe by a reliable partner (VisionSMT) we already know from previous projects. This, coupled with sourcing components only from official distributors (mostly Digi-Key), means we can be sure that no counterfeit or after-market components will be used. The same partner is also responsible for sourcing the PCBs, which - by experience - they are great at.

The cases were designed by and will be sourced from tec4data (Austria), also a partner we’ve had the pleasure to work with earlier, they have proven to be very competent and helpful.

The μArt from the side.

Risks & Challenges

The prototypes work flawlessly, and since they have been manufactured by the same proven supplier who will also fulfill the batch production, production problems down the line seem unlikely. Component procurement, however, might cause delays in shipments if there are not enough quantities available at the distributor.

The enclosures will be injection molded. Their designer and supplier, tec4data, provided multiple prototypes built using high-resolution 3D printing, so the form and mechanical details are already verified to be perfect. Necessarily however, these prototypes are from a different material than what is used in injection molding, so a delay in enclosure production is possible if an issue pops up during the transition. The mold itself is considered to be simple, bearing little risk if any at all, and tec4data has executed more difficult projects many times, as is evident from their website.

Shipping & Fulfillment

Backer rewards of the campaign will ship from Hungary, Europe. Rewards will be carried by the post, and if backers require tracking, they can choose registered shipment as an option in each pledge level. Please choose this option if you need support from us in case of carrier delays or problems.