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Arduino IDE vs DigiSpark issue

tm_stump

I've been looking for information about a small problem I encountered programming a Digispark board (attiny85) using the Arduino IDE and a Pololu pgm04b programmer.  The setup works without having to burn a bootloader to the digispark, but here is the issue.  If I upload the sketch using the digispark 1 or 8 Mhz board choices, the program runs as it should with no problems.  If I use one of the 16 or 16.5 MHz choices, the program runs extremely slow with maybe some other problems as the counter built in to count button pushes doesn't update.  I'm trying to find out what changes, exactly, are being made during compilation that provides a defect in the compiled program when using the higher speed choices.  I'm no expert, but I'm hoping that someone is aware of something I may be overlooking.  To throw a wrench into the works I might mention that this appears to be digispark clone so it's entirely possible that the ATtiny85 used on the board is not only not up to par but I guess there's a possibility it's not a genuine ATtiny.  I have some plain ATtiny85 on the way to try this without the digispark hardware overhead.

The sketch/program is just a simple program to count momentary button pushes, display the button push counts and allow an LED to blink on even numbered counts.

thanks,

TM

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  • 0

    This is just a guess and I did not read the datasheet, sometimes higher clock speed are only possible at either the high or low end of the voltage range of a chip. So it might do 16 Mhz only at 3.3 V or 5 V and your board is running on the wrong voltage. 

    Or if your text is correct and the board is running at 16 mHz, everything is running at milliHz speed. Rofl

  • 0 in reply to wolfgangfriedrich

    Thanks for the reply.  Just a typo, should have been Mhz.  Easy enough to try a different voltage.

    (added) Just varying the voltage has no effect on the problem.  Out of 5 Digispark clones, 1 appears 'normal' and 4 appear 'not normal'.  My #1 guess is that using the Digispark 16/16.5 Mhz board definitions generates code with a problem for these board or they're just plain defective at the higher speeds.  Is it possible that there is some built-in delay to make the Digisparks work OK but get out of control with the clones?  

    TM

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  • 0 in reply to wolfgangfriedrich

    Thanks for the reply.  Just a typo, should have been Mhz.  Easy enough to try a different voltage.

    (added) Just varying the voltage has no effect on the problem.  Out of 5 Digispark clones, 1 appears 'normal' and 4 appear 'not normal'.  My #1 guess is that using the Digispark 16/16.5 Mhz board definitions generates code with a problem for these board or they're just plain defective at the higher speeds.  Is it possible that there is some built-in delay to make the Digisparks work OK but get out of control with the clones?  

    TM

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  • 0 in reply to tm_stump

    Consulting the datasheet, there are 2 versions of the attiny85. The ATtiny85 which is spec'ed up to 20 MHz and the ATtiny85V which is specified only up to 10 MHz. I would be surprised that a clone would use the better and more expensive chip.

    Maybe you can read the marking on the chip and see if it reads "tiny85  20xx" or tiny85V  "10xx". The datasheet is quiet about chip markings but some images of the Digispark show it quite clearly. 

    image

  • 0 in reply to wolfgangfriedrich

    Thanks for the reply.
    I've checked the markings and all are -20SU. I'm in the process of running through the programming of each board at different speeds to see exactly what works and what doesn't. I can dump the info on each chip/board to compare the configuration of each to see if I can spot something. So far, the working and non-working board configs look the same, fuses included. I can do a bit more but I'm at the limits of my capabilities, for now. Having read about chip counterfeiting and what happens to chips that don't pass the testing AND for what these Digispark clones cost I think I'll probably write it off as just sub-par ATtiny. I have some ATtiny85 coming from a reputable supplier to see if the same issue exists. The markings on these ICs look too light and suspicious and different from some genuine ATtiny's I have but there's really no way to tell for sure. Anyway, these boards are just some pre-testing to learn the chip for a small project so buying a few more is not a problem.  If I get ambitious enough to build an HVSP I'll try the high voltage reset just for fun.

    On a different note, there seems to be some sort of delay between posting and the post showing up, or not showing up at all, even though it appears to have gone through. ???

    Thanks,
    TM