Tag: DigiSpark

DigiSpark ATTiny85 Revisited

Finally got the thing to program. I went and bought some of the semi-bare USB units. All told, I think you can get this device in 4 different forms (or more).

  1. Bare chip. Should be easy to program as long as you have the right voltages and drivers.
  2. Bare chip-on-a-board. Same as bare chip but it’s on its own breakout board with a little support circuitry
  3. USB with bare connection. Like some cheap thumb drives, the card edge plugs straight into a USB port.
  4. USB with mini/micro connection. Basically #3 except you connect via a standard USB cable.

It was case #4 I was having so much trouble with, so I bought some #3s figuring that they might match available docs better.

They did, and it gave me a clue as to why the #4 boards didn’t program.

The ATTiny85 is programmed via a slightly non-standard Arduino service called Micronucleus. Micronucleus goes straight to the USB hardware. And by straight, I mean that it doesn’t even expect the device in question to be a named OS device. In Linux, that means nothing appears under /dev when you plug the ATTiny USB device in.

I installed the udev rules given for Ubuntu into my Fedora system. I haven’t dissected them, but I’m pretty sure that that’s what they’re for – capturing the hotplug of the ATTiny device and keeping it from mapping to /dev. The access rules given were 0666 and by reading carefully over available documentation I learned that often running the Micronucleus utility as root would clear up the error I was getting: “Assertion `res >= 4′ failed.”

666 doesn’t allow “execute” rights, so maybe on Fedora that’s a problem. The other alternative would be an selinux problem, but my audit logs don’t seem to indicate that.

So, by running the entire IDE as root (pending further discovery), I can now upload to the DigiSpark. Once I had the case #3 units, the case #4 units worked as well. Apparently they’re essentially identical except for their connection hardware.

I’m now poised to enjoy this inexpensive but useful little device. All is not forgiven, which is why I leave my original complaints posted. But at least I no longer have a box of useless parts.

 

 

Why I’m not using DigiSpark’s ATTiny85 in Almost Everything

The DigiStump ATTiny85 board  is a really attractive bit of hardware. It’s cheap, it can be accessed via the on-board USB connector, and while it hasn’t got the advanced hardware features of its bigger kin, there are a lot of things you can do with its small number of ports, memory and features. I’ve got a list, in fact.

And I’m not getting anything on that list done, because I cannot program the device!

A good comparison to the ATTiny85 is the ESP-01 mini-board featuring the ESP8266 processor. That’s an 8-pin board, also with relatively few connectors. In fact, it doesn’t even have a USB connector. And in theory, it should be harder to work with, since it runs an internal WiFi tcp/ip stack!

But I haven’t had any problems with the ESP-01, while my ATTiny85 units sit in a box, unused and useless.

Why? Apparently this was a hit-and-run project. The documentation, once written, has no indications that it’s being kept up-to-date. There’s a wiki, but so far it’s not been of any help.

There are several things I fault in the documentation.

  1. As mentioned, I don’t think it’s up-to-date as regards current Arduino IDEs or the OS’s they run under. Vague hints are given that certain Version 1.6 IDE’s are not suited (why?????), but the current Arduino IDE is version 1.8. What does that mean?
  2. A big part of the documentation is an animation. I don’t like animations in the middle of instructions.
    1. The motion distracts from reading the bulk of the text.
    2. You cannot print out the documentation and read/annotate it offline. Unless you’re Harry Potter rendering the Daily Prophet, animations don’t print well.
    3. If your animation is not only auto-playing, but starts playing sound when the page is opened, that’s it. I’m gone. Don’t try to sell me anything again. Ever.
  3. Pre-requisites. A side link points Linux users to some udev rules. I have problems with this, because first, the rules don’t actually explain what they are doing (If I read them correctly, they prevent the ATTiny85 from automatically creating /dev/ttyUSB and /dev/ACM devices, but don’t tell udev not to try and treat them as mountable USB drives). And secondly, there’s no explanation as to what to expect when things work right. Or, worse, what you’ll see/not see, if they’re wrong. Popular udev rules often end up as part of stock distros, so it’s important to know if you’re likely to do something that’s redundant or even counter-productive.
  4. Devices. Unlike most Arduino interfaces, I don’t think that the DigiSpark programmer actually uses any of the listed available devices on the Tools menus, but instead talks straight to hardware (presumably by scanning USB and looking for one (or more???) 16d0:0753 MCS Digistump DigiSpark units. But it would be nice if that had been explicitly mentioned, precisely because it’s not the usual mode of operation.
  5. Operation. There’s no indication of what you should see when a sketch uploads. The IDE isn’t uploading via normal channels, so its own messages are actually misleading. And it was only after a lot of looking around that I even saw a listing of something more like what’s to be expected.
  6. Diagnosis. As far as I can tell, there’s absolutely no error messages that ever print out if the IDE doesn’t connect, much less what couldn’t be connected to or possibly why. And so, I’m left frustrated, with no clue as to which of several subsystems are at fault. Much less how to diagnose or correct them.

Bottom line

Yes, it’s a nice device. Too bad I cannot use it. It takes up space in my parts box. And until Digispark spends some time and effort on making it useful, I won’t be buying any more of them. Because no matter how cheap they are, cheap and useless is too expensive. I won’t be buying any Digispark products until I hear that they’re committed to making said products usable. Even if this isn’t one of their more profitable units, it indicates how little they are willing to commit and thus a baseline on how much confidence I can expect from more advanced offerings.

I’ve got decades of experience on all sorts of equipment. It’s generally been my job to figure out how to work with new and unusual hardware and software. But this is simply more trouble than it’s worth.