is there a similar IC to the Attiny85 with less i/O and cheaper?

[bigjoncoop]

is there a similar IC to the Attiny85 with less i/O and cheaper?

A lot of times I only use 2 I/O pins on the ATTINY85 and was wondering if there's  a cheaper IC that I can still program the same why with just less I/O pins?

[grrmachine]

I use a lot of cheap 8-bit controllers from Holtek. They have a lot of functionality for the cost and I put a lot of them into high volume cost-controlled products. Especially the ones with flash like HT66F0021, HT68F if you could access them and get the programmer it would be ideal for a hobbyist. https://www.holtek.com/producthome/-/pid/402/422
There have some dirt cheap OTP versions available and also look at Padauk, they have some open programmer developed and the chips are available at LCSC.

[WattsThat]

Hard to answer without more details. In AVR? The general response is not really. The 25 with less memory should be cheaper but... You may not find any of the older AVR parts to be any cheaper than the 84/85 as they are at or nearing end of life and that’s where the volume is.

To move to the newer, cheaper tinyAVR-0/1/2 parts, you’ll need a UPDI programmer. You can build one from an Arduino Nano/mini in a pinch. There you’ll find some 6 pin surface mount parts.

[RoGeorge]

is there a similar IC to the Attiny85 with less i/O and cheaper?

Maybe ATtiny13?  But I think the smallest pin count is 8.

From other producers I've heard Padauk has some dirt-cheap MCUs, only a few cents.  There are some threads about Padauk MCUs on the EEVblog, IDK which one to recommend https://www.eevblog.com/forum/microcontrollers/padauk-pfs154-getting-started/

UPDI programmer

If that's the same as the so called debug wire, I've made one out of a USB to serial adapter and a diode.  It works as a hardware debugger, with hardware breakpoints, memory change/inspect, GDB, GUI from Eclipse and all the fancy debugging features:  https://www.eevblog.com/forum/microcontrollers/avr-(arduino)-linux-debug/

[Miyuki]

Attiny 4/5/9 are way cheaper in SOT-23-6 (about $0.35) - The Tiny Programming Interface (TPI)
Or that new ATTINY202 in SOIC8 (about $0.425) - Single Pin Unified Program Debug Interface (UPDI)

[MarkR42]

The Attiny10-tshr is currently unavailable anywhere. However, the Attiny5-tshr is in the same series and there appears to be some stock in the supply chain.

I really enjoyed programming the attiny4/5/9/10 series it's a lot of fun having 32 bytes of memory and very little flash. But my firmware all fitted in and was written completely in C (no assembly!)

[Jeroen3]

The Attiny10-tshr is currently unavailable anywhere. However, the Attiny5-tshr is in the same series and there appears to be some stock in the supply chain.

I really enjoyed programming the attiny4/5/9/10 series it's a lot of fun having 32 bytes of memory and very little flash. But my firmware all fitted in and was written completely in C (no assembly!)

Programming a tiny10 in C requires so much compiler tuning. Basically you cannot have any function calls. Because it can't fit a stackframe. Fun though.
Like the 8051 days.

[RoGeorge]

IIRC, the GCC-AVR has a setting for stack size.  Other compilers should be able to set that, too.

[MarkR42]

The tiny10 does not need super-tuning, I wrote my firmware in C with loads of function calls and it's still only 390 bytes and does not use much (any?) stack.

I enabled link-time optimisation and used "static" prefix for most things. The compiler seems to have inlined everything.

[bingo600]

is there a similar IC to the Attiny85 with less i/O and cheaper?

Maybe ATtiny13?  But I think the smallest pin count is 8.

From other producers I've heard Padauk has some dirt-cheap MCUs, only a few cents.  There are some threads about Padauk MCUs on the EEVblog, IDK which one to recommend https://www.eevblog.com/forum/microcontrollers/padauk-pfs154-getting-started/

This is the best Pada thread
https://www.eevblog.com/forum/blog/eevblog-1144-padauk-programmer-reverse-engineering/

[jmelson]

is there a similar IC to the Attiny85 with less i/O and cheaper?

Maybe ATtiny13?  But I think the smallest pin count is 8.

Yes, I used the ATtiny13A in a project, 8 pin SOIC, it worked great.  I used the Sparkfun "tiny programmer" to program it from USB.  That programmer cost about $16.  The ATtiny13A can run off 5 V, too.
Jon

[westfw]

To move to the newer, cheaper tinyAVR-0/1/2 parts, you’ll need a UPDI programmer.

The tiny0/1/2 are pretty nice chips - lots of peripherals and significantly cheaper than a tiny85.  While there aren't any "less pins" options, there are a bunch of "smaller package" options.
And UPDI is pretty nice compared to previous program/debug protocols.

There you’ll find some 6 pin surface mount parts.

The 6pin parts are NOT tiny0/1/2.  Affectionately known as "brain dead" chips, they have tiny memories and half the registers of regular AVRs, and essentially no peripherals
Also, you'll need a "TPI" programmer, which are less widely implemented than either ISP or UPDI.
Not recommended, unless you really need that SOT23-6 package.