It should be noted that AVRs still come in PDIP28 even today. The smaller form factors (6-pin, 8-pin, or 14-pin) are surface-mount only though.
Still, if your main goal is PDIP or through-hole form factor, I recommend buying the PDIP28 versions of these chips where possible.
I use these little adapter boards for breadboard prototyping. I don’t keep DIPs around anymore because I don’t use them. I have ZIF to DIP adapters for most of the chips for orgasming but for breadboard development I find these little boards work just fine.
The main issue with those adapter boards is that an entire custom PCB is like $7 these days (albeit you need to order multiple copies, plus shipping…). But lets say a 4x copies of some custom PCB costs ya $35 after shipping.
That’s an American manufacturer too: Digikey Red. Other parts of the world can be cheaper depending on shipping costs.
So spending $3 to $5 on these little converter boards feels… weird (plus shipping)? If going for prototyping purposes, spending $2.50 on a 28-pin PDIP28 that you can just plop-down onto a breadboard or whatever is probably better?
I do miss the 8-pin PDIPs. I know the older chips (ATMega328) used to come in smaller 8-pin or 14-pin PDIP forms, but Microchip’s newer chips are PDIP28 only.
Prototyping is important. The main benefit is getting a prototype done ASAP to iterate on your designs. But is it too difficult to switch from 28-pin prototypes to 14-pin final products? (Ex: AVR32dd28 PDIP-28 for prototyping, then switch to the AVR32DD14 SOIC-14 for the final custom pcb design?)
The little adapter boards cost pennies each and I stock them in quantities of tens or hundreds.
I order components in rolls of hundreds or thousands and ordering one or two in a different package is an extra operation that takes time. I need to make sure that I’m ordering the exact same part and often, with modern parts, there is no DIP package available. Sure, that works if you’re limiting yourself to ATTINY328Ps. I’ve got a few dozen 328Ps in QFP32s and around a dozen DIP28s. I have a couple of dozen 328PBs which are only available in TQFPs.
Some of the chips in this photo are available as DIPs (ATTINY84 and 85) the others (ATTINY8, 9, 402, 412, 1614) are not.
There are a LOT of components that simply aren’t available in DIP packages so if you want to breadboard or you want to make sure that you’re using the exact chip for prototyping these little adapter boards are a great option and they’re one that I choose to use.
Do you really need to match the exact chip? I think in practice, sharing across the family is good enough.
Lets focus on two formats. I’m sure you know AVR DD has the 28-pin PDIP that we’ve talked about before. But the 20-pin VQFN (3mm x 3mm) is perhaps what you’re not familiar with. Its electrically compatible with the 28-pin PDIP (just 20-pins instead) and shares the data-sheet / features and everything (same RAM, same assembly, same datasheets and properties).
So my overall argument is that the 28-pin PDIP should be a fine-enough prototype for a 20-pin VQFN final product. Maybe with an intermediate prototype with a 20-pin SOIC (SOIC is a good deal easier to solder after all) if you wanted something that matched pin-for-pin that didn’t require quite the same level of difficulty to solder.
Note that the 20-pin VQFN AVR32DD20 (https://www.digikey.com/en/products/detail/microchip-technology/AVR32DD20-I-REB/16643834) is at that $1 mark, sure a bit more expensive than ATTiny4 but if its space you’re concerned about, the VQFN package at 3mm x 3mm is damn near the 2.8mm x 2.9mm of the SOT-23 6-pin. Aside from the pain in the ass it is to work with leadless (though doable on hobby budgets with a hot-air gun, pancake griddle and solder paste), its not like these small 3mm x 3mm packages are outside of our reach!
With knowledge that modern Microchip chips offer VQFN-20 chips in the 3mm x 3mm footprint, it does feel like SOT-23 6 packages like the ATTiny4 are kind of obsolete. After all, might as well shove 20-pins into that space with today’s level of miniaturization.
I guess the ATTiny4 is cheaper though (under 50-cents in bulk). But the variety of packages offered here by Microchip is basically just for prototyping. SOIC-14, TQFP-32, PDIP-28, SSOP-28… these are all far larger than the VQFN-20 (3mm x 3mm) and VQFN-32 (5mm x 5mm) footprints that would go into a final productized design.
This seems really important to you. It isn’t to me.
I am not going to go back to buying DIP packages of chips. These little adapter boards costs pennies, are easy to solder, and let me use the exact chip that I’m going to use in the production boards on my breadboards. I’m going to keep doing that.
You’re free to use DIP chips if that’s what you want to do.
I’m trying to make it clear to people who might be intimidated by modern SMD chips that there are options that will let them use chips that they could otherwise not use, like the ATMEGA328PB or LGT8F328P which only come in TQFP of the ATTINY 1612 which only comes in SOIC-14, while still using their breadboards and Dupont wires.
There is no right option, only the options that’s right for me, and the option that’s right for you.
