I am planning to buy & make a small project with ATTiny85.
Already have Arduino Uno R 3 and want to use it as Arduino as ISP Programmer.
Found some ATTiny85 boards with USB connectors ( "C" or board foil) & 5V voltage regulator, with or without ATTiny85 chip.
--Are these features (USB connection & 5V regulator) useful for anything if I use Arduino as ISP programmer ?
--Is it more practical & economical just to buy some DIP8 ATTiny 85 chips and use them an empty breadboard with with jumper wires to Arduino ?
--What is the latest & the smallest bootloader to load ?
Thanks!
From the ISP programming side, no. 5V regulator will be good depending on how your project will be fed.
The models that can connect to USB should have a specific bootloader to be able to be programmed through PC. To the bare attiny you can burn the bootloader directly from the Arduino IDE.
Here lies the biggest problem. Digispark doesn't provide support for the boards anymore and Spence Konde's site had certificate problems. So, downloading the appropriate core has been a headache recently. I don't know if the problems with the site were solved.
And here the second problem. Bare chips ordered few pcs might cost you more than complete dev boards. I would say it doesn't make any sense for hobby/ low quantity production.
That's true! Good point to consider.
Well, that I disagree. As a hobby, you want to have fun and deal with different microcontrollers. I had a lot of fun developing for Attiny85 
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Thank you for all replies.
"The models that can connect to USB should have a specific bootloader to be able to be programmed through PC."
Are these cheap Chinese clones have a bootloader?
Does the USB capable bootloader takes up more mem space?
Does Arduino IDE recognizes the USB as serial connection?
Thanks!
Well, from your pic on post #1, I have one of these (Digispark) and it does have a bootloader.
Yes it does. Not much more, but yet more.
Not exactly. When you want to upload your sketch there's a specific moment to plug the board. You don't get serial feedback though (can't use the serial monitor, for example, but you also can't with a bare Attiny85).
What I like about the ATTiny, that I could put a small DIP8 socket into a finished project, and simply just plug in the 8 pin ATTiny after programming/reprogramming.
Considering also aNano, however it will take much more space.
I built a USBTinyISP, mostly following this guide. I did however, use a 3.3 V regulator and got rid of the Zeners all together. Some day I'll add a LED so the programming is visible.
It's not fair to compare full development board with bare chip.
What about Esp32-c3 supermini? Compare the specs...
Ps. I played with dip8 Attiny85s ten years ago as well.. Spent a lot of time to optimize everything to fit in tiny resources. Lot of learning.
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I think I used the Damellis core last time I used an ATtiny85.
Leo..
Yup, me too.
Esp32-c3 supermini
Thank you for the suggestion, it looks better option than a Nano
This should be fixed now:
https://github.com/SpenceKonde/ATTinyCore/issues/891#issuecomment-2515502681
fixed, had forgotten to restart the second server after renewing cert for
it and rebooting it to make it pick up the recent kernal updates I ran to
keep it up to date (I've seen what happens to linux systems that don't get
this treatment - evetually the cert they have to verify SSL against
expires, andf you con't uprade them because it can't make an SSL connection
because it thinks the SSL server is compromised, and you need to either get
wizards involved to correct it, or you blow it away and rebuild. It took
me over a month to do that last summer when i accidentally deleted the
running apache binary out from under it which kept working until the cert
ran out).
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Are these cheap Chinese clones have a bootloader?
Maybe. They SHOULD have either the digispark or micronucleus bootloader, but... not all vendors are equal.
Does the USB capable bootloader takes up more mem space?
Yes. It's "about 2k" vs about "about 0.5k" for a serial bootloader.
Does Arduino IDE recognizes the USB as serial connection?
No. It just does a low-speed USB download thing. The tiny85 doesn't have a UART, either...
Note that if you're using "Arduino as ISP" or other ISP programmer, you don't need the bootloader...
You might want to investigate one of the newer AVRs, like the AVR16EB14 or AVR32du14. More memory, more peripherals, and even cheaper... (no 8pin versions, though.)
I'm surprised that no-one has done a digiSpark-sized board using one of these. Other than the whole "trivial open-source designs will be cloned so fast that it'll be difficult to recover development costs" thing...
I think it's just difficult to compete with mini-size Exp8266, Esp32-c3 and RP2040 boards that are selling ~$2.
Arduino could make one supermini-board though...
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I found the ATtiny85 to be rather expensive as a DIP, i Stick with ATtiny13 if that has enough space, and otherwise move to Pro-mini boards. ATtiny13a is also practical for smaller projects and the SMT package is easy enough to use as well. (just need a solderless programming socket)
Also comparing the suggested Esp32-c3 and Esp32-s2.
As I do not see any use for Bluetooth in my projects, the s2 maybe a better choice: although it has slightly less flash, higher speed, mem USB Otg, serial print
Any opinion on the C3 vs S2 ?
Afaik there is no "supermini" form for S2.
For S3 yes.
C3 being the cheapest one.
Correct, the S2 is 43.3 x 25.4 mm, and C3 is 22.5 x 18 mm.
I could get either from AliExp for the same price with Welcome New User.
I see more value with C3 or S3 for the supermini size.