For those of us old enough to remember those chunky 9-pin D-connectors from the ‘90s, it’ll come as no surprise to know that they’re still around—as is the RS-232 protocol that used to travel over the cables they connected. These days, the connectors are mostly used by industry and RS-232 has survived well into the iPhone era. We will probably end up plugging starships together with those things.
However, although the difference is more in the detail and the ubiquitous MAX-232 converts the two fairly seamlessly, for the rest of us TTL rather than RS-232 serial is now far more common. As are the needed USB-to-serial cables.
The reason why I have a pile of cables and boards on my desk is that I’ve never found one that did everything I need, and they tend to be rather unreliable.
I get sent new boards weekly, my mailbag generally being stuffed with new hardware that people want me to write about, and not all the boards work with all USB-to-serial cables. It’s hard to tell whether it’s the cables or the boards that are at fault, though anecdotally a lot of ESP8266-based boards seem quite temperamental and picky about what USB-to-serial adapter you use, but the fact remains. I need a selection to get all those boards working.
The μArt board claims it’s going to solve that. Firstly, it’ll work at a range of voltages, from 1.8 to 5.4 V — which means that, while it won’t work at RS-232 voltage levels, it should be suitable for most single-board computers and microcontrollers—and has voltage auto-sensing.
Unlike some of the cheaper connectors, the board can be used for flashing firmware as well as straight serial communications, with up to a 3Mbps transfer speed — good luck getting most boards to talk at those sorts of speeds.
The μArt looks to be pretty robust and able to tolerates wiring mistakes without taking or causing damage to your board or laptop. It is galvanically isolated—up to mains-level voltages—and polarity protection which means that, at least in theory, you shouldn’t be able to fry your laptop no matter how you mis-connect the wiring.
All the inputs have pull up resistors—so that disconnected pins don’t cause trouble—over-current protection, and external pins also have ESD protection.
There are even GPIO pins available that you can control over USB, in parallel to the UART lines, which can be reconfigured to provide remote wake up functionality for instance.
No pricing has been announced, but the μArt is coming soon on Crowd Supply. I’m probably going to pick one up and add it to the pile. You never know, maybe this will be the USB-to-serial board that works with all the things?
UPDATE: μArt’s Crowd Supply campaign is now underway, starting at $32 for a single unit. Delivery is slated for mid-November.