Greetings All,
Can anyone tell me if a lower ATTiny (the 4,5,9,or 10) can be used, in any practical sense, as an ISP for the higher ATTiny (45 or 85)?
Greetings All,
Can anyone tell me if a lower ATTiny (the 4,5,9,or 10) can be used, in any practical sense, as an ISP for the higher ATTiny (45 or 85)?
You need a minimum of 6 i/o pins to communicate with the host and target. Iirc many of those parts dont havr thst many. Fitting the code into the minuscule flash would also be hard (though they managed to fit vusb anf ISP programming functionality into 2k for the usbtinyisp, which uses the 2313)
Why use another part as an ISP when you can put a bootloader on the attiny and program it over serial? (Or usb st a higher cost in flash)
Thanks for that! That's a very good suggestion since board space in this project is at an extreme premium. Do you know of any schematic examples for connecting, in this case an ATTiny84, to USB directly?
musclenerdzllc:
Thanks for that! That's a very good suggestion since board space in this project is at an extreme premium. Do you know of any schematic examples for connecting, in this case an ATTiny84, to USB directly?
It's a resistor and zener diode on each of the two USB data lines, IIRC.
I don't mess with the vusb bootloader myself - it hogs flash and I dislike it on principle - I'd rather use an external ISP programmer, or a serial bootloader and external serial adapter. The VUSB bootloader is called micronucleus, and there are guides, I think the first google result for it shows a tiny84, actually....
Note that my core doesn't (easily) support the VUSB bootloaders; I looked into it, but I had trouble figuring out how to make my core upload to it (though you can export the hex file and upload that manually if you want the enhanced features that my core has vs most ATTiny cores).