Building a Digispark compatible breadboard circuit

[jaghvi]

Can this board be used for serial data in,like in case a temp sensor is interfaced with it?? .As it doesn't have a inbuilt usb-serial converter .

[Bluebie]

Sure - you can communicate temperature to your computer using DigiUSB (which works a bit like serial) or enter it in as a keyboard with the DigiKeyboard library, or communicate the numbers via the DigiJoystick library. Joystick interfaces are an interesting option because they are designed for communicating numbers in a range which change over time. The numbers are communicated with digital precision, so a temperature input would work great with it. Plus, you could even use your temperature sensor to play games

[Bluebie]

We do not have permission to view this drawing

[jaghvi]

i have all the aforementioned components to build a digispark on a breadboard.Now I want to know ,if i can burn the hex file using arduino as isp.I have arduino uno and no other ISP module?So is it feasible.

[Bluebie]

Yes, you can upload a bootloader to an attiny85-20 from within the digispark environment by selecting whichever kind of programmer you are using in the Programmer menu under tools, then connect the chip to the programmer and select Burn Bootloader. This will install the standard digispark bootloader, but will also disable access to the chip using an ISP programmer, enabling your programs to use the reset pin for whatever. After this, change the "Programmer" back to Digispark and connect the circuit to USB, and see if you can upload a simple program in the usual way.


Arduino ISP will be fine, or you can use a digispark by uploading the LittleWire firmware and connecting every pin from the littlewire digispark directly to the same pin on your hand made digispark, except for pins 3 and 4, which are used for USB between the littlewire and the computer. For LittleWire the programmer you should select is 'USBtinyISP'.


You say "I have all the aforementioned components" but you haven't shown us anything like that. You still haven't fixed your image so anyone but yourself can see it, so I have no idea what is in that picture.

[jaghvi]

I burned the bootloader on attiny85 finally
but serial port greyed out in the ide

[jaghvi]

@probono...why have u used d- and d+ as 6 and 7 pins resp.
When everywhere 2,3 are used for usb comm.
I have burned the bootloader and set fuses but yet its not detected

[Bluebie]

Digispark does not use a serial port. Set the programmer to Digispark and the Board to one of the Digispark variants and you should be able to upload to it if the bootloader really was installed correctly. Otherwise you have something wrong in your circuit.


Getting this USB stuff working is annoying - the circuit can be very dependant on the quality of the components you use. This is precisely why it is nice to just buy a little circuit board like the digispark and plug it in and not worry about all this stuff!

[jaghvi]

It was because 90-digispark.rules was not there in my /etc/udev/rules.d....everything working great now. and followed steps of probono except used pins 2 and 3 as data lines and had to add 49-micronucleus.rules and 90-digispark.rules in /etc/udev/rules.
 

[jaghvi]

@bluebie
trying to burn the cdc.hex file from avrdude ,detects the onboard digispark as ttyACM device but the sketch wont upload on the board.
But if its uploaded from micronuceleus command line it works fine ??

[Bluebie]

the 'ttyACM' device will be your programmer, not the attiny85 chip itself. Your programmer is unable to program this chip now, because you have used the burn bootloader function to install the bootloader and change it's fuses disabling the 'reset pin' function. This allows you to use all six pins, but you cannot use an ISP programmer anymore to upload to this chip. You will need a high voltage serial programmer to upload directly to it now, or you can use a high voltage serial programmer or a 'tiny fuse resetter' (which is a simplified hvsp device) to reset the fuses to erase the chip, setting the fuses back to the default value where the reset pin is used to make the chip accept a new program upload instead of being used for general IO inside the programs you upload. I should have made it more clear that your tiny85 would loose this hardware reset function if you Burn Bootloader.


The upside is it isn't too tricky to make a tiny fuse resetter - you just need a 12v power source (like a little 12v battery) and a transistor, and you should be able to do the rest with a digispark or an unburnt attiny85 or something like that. The web has instructions on how to make these gadgets on a breadboard.

[dougal]

Speaking of HVSP, is there any good source to get one for less than $50?


I might break down and get one eventually in any case. But if I could find one closer to $30, I might do it sooner than later.

[Bluebie]

I have no idea. I don't own one. I've only lost five or so chips to this sort of bricking, which is a heck of a lot cheaper than $50... This is one of the problems I made micronucleus to address - so we can use all six pins in a nice simple way, without needing an expensive programmer or dangerously high voltages (to the rest of the components in a circuit)

[dougal]

Yeah, you're right. I don't know why I'm considering the purchase of a HVSP just to recover one bricked
Digispark (well, and any possible future ones). I could buy 4 or 5 new ones, instead. Or a USBISP and some bare AVR chips.


I think instead, I'll use my bricked Digispark for soldering/desoldering practice. I can extract the power regulator, LEDs and such for other stuff.

[Bluebie]

How'd you brick a digispark? Were you using flash memory to store data and accidentally wrote over the bootloader or something?


_{hoping there aren't secretly any horrible bugs in my code which ruined your thingie.}