How about a Digispark for the ATTiny84 series of chips?

[digistump]

re: Schottky - I'm not sure how many people use external power, but I know that I often have it attached because I am reprogramming a circuit in place, or programming a circuit that uses more than 100/500ma. I also know some of our commercial users have a need for it because they upgrade in place. Regarding them blowing - if they blow they saved you from blowing out the Attiny in many cases! So for power users they act as a one time cheap safety device. Because of this I don't see any disadvantage having them, the voltage drop is well in spec, when they blow out something else would have likely blown otherwise, and they cost about 1 cent, so I'll concede they may not be as necessary as I originally thought, but there certainly doesn't seem to be an advantage to removing them.


re: Fuse -I expected everyone to demand a fuse, I have to date only had two people request one - they are over 10 cents each so unless people speak up they probably are not one the feature list at this point.


re:Microsd footprint - I see no reason not to put footprints for everything possible on the bottom - microsd makes sense because it doesn't need any other components. If there is room I'll put it on - that space is tight even for traces. Definitely a shield regardless


I still debate the snap off usb plug, but agree with the footprint for a micro usb on the bottom (lets avoid a mini vs micro debate - I prefer mini, but micro is far cheaper, doesn't require holes int he board which we don't have room for, and not at end of life) - at the very least the traces will be done in a way that the plug can be cut off with no ill effects.


Expanding on going to parallel pins - I'm also trying to make it so with a set of risers you can plug in two Digispark shields and have them use different sets of pins!


Thanks everyone for contributing!

[CBcracker]

I'm less concerned about accidentally leaving the digispark hooked up to another power source and more concerned about capacitors and inductors in my circuit creating voltage spikes which could render the sensitive high speed processors with firmware in ram on my computer corrupt and perhaps even unconscious.

OK, now you're being ridiculous.  Did you stay inside last week during the perseids meteor shower out of concern you might get hit? The chance of frying your whole computer from something you plug into the USB port are next to nil.  Worst case scenario is you fry the port, and even that's hard to do.

[CBcracker]

re: Schottky - [...] Regarding them blowing - if they blow they saved you from blowing out the Attiny in many cases!

Actually, one blew by accidentally shorting 5v to gnd.  The other blew because I fed 5v to one of the NRF modules instead of 3.3v, causing it to temporarily draw enough current to short the schottky.  Neither case would have damaged the ATtiny.  In the second case, it *may* have saved the NRF from blowing, if it actually did blow, but I haven't tested it yet.

[digistump]

I do think that some of the Schottky's were a bit more sensitive than the design called for (due to a factory substitution) - the Pro ones will handle more current so the second case should be OK - the solution for 5v to ground short I think is for me to add proper reverse polarity protection (if I were to add a single protection feature THAT would be the most helpful based on the mistakes people have made with them).

[digistump]

@Bluebie - the MicroSD doesn't seem practical - the layout has headers on all 4 sides so unless I find a good hinged slot layout one they would be in the way. MicroUSB presents the same problem - put the footprint on the back of the USB plug and it is out int he open, but put it on the bottom of the main part and it is blocked by the headers

[defragster]

USB Safety is important - especially with an exposed metal consumer device.  My years past Sony Phone cable had plastic end alignment pins and exposed contact pins.  That first Gen core 2 duo box I built is still in my shop running all USB from PCI board.  One 'zap' and all MOBO USB subsystems failed to exist after the shocking reset the system encountered when I walked over and grabbed the cable to connect my phone.

[TimO]

Has there been any movement on this?  Whilst I appreciated that the DigiX has probably kept you busy (and that's good, I've got a couple myself), I wondered whether you've moved the design for the DigiSpark Plus (or whatever it's likely to be called) along any further.

A 1634 based DigiSpark with more IO and memory would be a very nice little item.  The only similar board I've seen, is the MT-T34, which whilst very close to this sort of functionality, and not overly expensive, only provides 250mA from it's regulator (vs the 500mA the DigiSpark can source, which is very useful), and of course isn't compatible with the DigiSpark shields.

[gogol]

http://www.kickstarter.com/projects/digistump/digix-the-ultimate-arduino-compatible-board-with-w/posts/669863
Read the last paragraph!
Looks like, that the conceptual work is done.

[digistump]

The pro is pretty much ready to go - I just have to wrap up some things before I can launch it - estimated launch is early Feb. on Kickstarter (or similar)

It will launch with an optional WiFi shield, microSD, and nRF shield.

We'll let everyone on our mailing list know when it launches - you can join the mailing list from the left side bar at digistump.com

We won't be using the 1634 because we'd be limited to 12Mhz for V-USB to work, which would break a lot of existing Arduino libraries/compatibility. I'd like to make a 1634 based one at some point - but we want the Pro to be more user friendly then the original, not less.

[TimO]

... We won't be using the 1634 because we'd be limited to 12Mhz for V-USB to work, which would break a lot of existing Arduino libraries/compatibility. I'd like to make a 1634 based one at some point - but we want the Pro to be more user friendly then the original, not less.

Aha, I wondered about that.  The discussion up thread seem to gravitate towards the 1634, but as you say, the maximum 12MHz was probably sub-optimal.

[TimO]

So, looking at the image on the DigiStump home page, it looks like they've gone with the ATtiny167, which should make for a good DigiStamp Pro, hopefully with 16k of Flash, and up to 16 IO lines, and running at up to 16MHz, as mentioned previously (It could also be a Attiny87, with only 8k of Flash, but I'd imagine the cost savings of going that way would only be small).

It appears to have 18 DIL pins, which I'm guessing are all 16 IO lines, and two power pins, with the three other pins at right angles to those, being the traditional set of Digispark power lines, allowing for compatibility with the original nine pin Digispark, and its shields.

It's also got a real USB connector instead of a the USB plug, which I imagine increases the cost, but is a welcome addition to make the design more able to withstand multiple plug/unplug cycles.

[digistump]

You got it exactly!

It is the 167 - we also have some software breakthroughs to release at the same time which will make using the Pro much more like using an Arduino.

We're dotting our "i"s and getting things approved and quoted then we will launch!

[dougal]

Woot! Can't wait!

[gogol]

It appears to have 18 DIL pins, which I'm guessing are all 16 IO lines, and two power pins, with the three other pins at right angles to those, being the traditional set of Digispark power lines, allowing for compatibility with the original nine pin Digispark, and its shields.

Reading the datasheet, I expect the 18 pins to be the 16 IO pins and AVCC/AVGND for the analog supply voltage.

hopefully with 16k of Flash,

as it is the 167 and not the 87 there is no question ;-)

It may have with the LIN/UART a much better serial connection.
So for me the big surprise will be which pins go for USB and will be restricted due to zener and pullup.  PB3 and PB6 seem to are those, with the least impact to special functions.

Is reset disabled or not? Two pins will go away for the quartz. One may have the LED.  So there should be at least 10 raw pins available.

[gogol]

Is that a button on the left side of the usb-jack?
Where is that button connected to? Reset?