Difference between ATTINY's

Hey all,

Super quick question: what's the difference between the ATTINY13A-SSU with the dot that denotes pin 1, and the ATTINY13A-SSU with the notch that denotes pin 1?

Apart from the mark for pin 1, everything else appears identical. They have the same text and the same model name.

The only thing I can say for certain is that one works with my firmware and the other is a f&*%ing piece of s&%*.

- Matt

EDIT: Good ATTINY has the notch.

Possibly a fake? Where'd it come from?

No idea. I have a bin full of reclaimed ATTINY13's that I've collected over the years from modifying NANJG drivers. I thought they were all the same but after nearly 3 days of trouble shooting (the MCU was not considered to be the problem) I noticed the MCU I was using had a dot instead of a notch. Swapped out the MCU, re-flashed and viola.

Try another one with a dot, does it fail, too?

Literally writing to you now :)

I have no others. Well, that is to say I can't find one.

I've never seen one that had anything other than the dimple/dot for pin 1.

edit: Any markings on the underside?

The ones that work are all off NANJG drivers. They have a notch marking pin 1. I'll take the dodgy one off the PCB tomorrow as I've just packed my reflow station away and intend on hitting the sack soon. I'll also dig through my parts bin and see if I can find some others.


I'll grab some tonight when I get home from work.

When you say 'notch' do you mean a U-shaped cutout at one end of the package, or the little round divot next to pin 1? I've never seen them with a painted/printed dot or a U-shaped notch, only the little round divot thing. All of them also have a good bit of printing on the underside that I've never looked at too closely, though I have around 50 on hand mixed between -SSU & a few -SSH if you need a known-good reference.

It's a notch that runs from the edge of the device inwards. It's not 'self contained' if that makes any sense what-so-ever. I'll have to get photos tonight.

I've never noticed that before... and they're mixed, no rhyme or reason to it that I can see.

YES! That's what I'm talking about. With my firmware I only got consistent behavior with the notched MCUs. Maybe you can have a look, but is there any difference in regards to the text on the chips?

It would be good to know what the differences are because the firmware worked on one, but not the other when the same upload settings were used. Something is different and maybe the code needs to be modified to ensure compatibility or something? I know which one it does work on, so I'll try and always use the correct model, but it'd be good to know what's going on so issues can be avoided in the future.

Any ideas? Anyone?

I noticed the text is different on top: 1350 and 1409. This seems to relate to 'change sets'. I can't find any layman's description as to what this exactly means, but I'm guessing it must be some really low level change to how the device operates. This may have an impact on how some code runs perhaps?

Can’t really answer anything, just addind a little info I’ve found from exp.

I’ve only ever gotten the notched ones on drivers, all the bare ones I’ve ever gotten from both digikey and mouser have been dots.

Interesting, never recognized this but I have both and never had problems on any of them.

What problems occur? Have you set the fuses correctly?

Yeah the notched ones all seem to be from NANJG drivers. I have ordered some from Farnell and mouser before but I cannot recall what markings they had. The notched ones have the lower number which means (I think) they are older. There is a distinct possibility that the cheap Chinese drivers are using superseded (but still perfectly fine) MCUs.

Really I think my problem boils down to how the firmware was written and some possible incompatibility with the newer revisions of the ATTINY. Maybe.

Fuses were set correctly yes.

Simply put 2 pins on the MCU are tied to ground through a switch. If one or both of the pins are pulled low, the MCU reacts by outputting a voltage on another pin. The output was either 0V or VCC, nothing in between. The problem was that under a specific scenario it was only outputting 0.9V. In other scenarios the pin was perfectly capable of outputting the full VCC voltage.

Another issue was that the MCU was outputting a voltage of VCC on a separate pin when the switches were closed. This voltage was then fed through a voltage divider and read on another pin. It is basically an on-demand voltage check. This pin was also outputting only 0.9V.

The firmware is tested and working on the 1350 ATTINY13A which leads me to believe there is an incompatibility with the firmware and the 1409 ATTINY13A.

EDIT: I keep thinking back to a problem PilotPTK had once where there was an undocumented bug (or it was documented but Digikey/Mouser did not mark their inventory properly or something) with some PICs. It resulted in his code working on one set of devices but not another, seemingly identical, set. I'm not saying this is a bug, just that whilst they should be more or less the same, these ATTINY chips are clearly(?) not.

... or just this single one MCU is toast. Unless this problem is reproducible, it might be too early to generalize.

That is true, but I had the same issue using a Tiny13V-10SSU. I dismissed those problems because of the frequency differences.

To be clear I'm not blaming the firmware or criticizing the MCU. They just appear to be slightly incompatible. When I have time I will find another of the newer MCUs and retry.