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Comment by vardump | Hacker News Reader

Is it just me, or are ATtinys surprisingly expensive chips? 55 cents for an ATtiny402 for instance. 4k Flash, 8 pins.

Something to do with the chip shortage?

It depends on your volume and target price.

Are you trying to put a microcontroller, a battery, a couple switches, and some LEDs/speakers in an injection-molded, basically disposable, consumer good to sell through McDonalds Happy Meals, Walmart, or AliExpress, and you plan to build hundreds of thousands to hundreds of millions of units? Do you expect to program in assembly, or a custom subset of something C-like that obviously won't include the standard library but might not even include something as fundamental as any values on the call stack for arguments or returns, happily trading a couple weeks of developer frustration if it saves $0.01 per part? No, the ATTiny doesn't really make sense for you....find a Chinese 8051 or Paduk core you can epoxy down chip-on-board style, aiming for the absolute bare minimum of peripherals and costs.

Are you producing some high-value commercial good in small quantities? Do you place a high value on developer productivity, want a generous assortment of peripherals and interrupts including communication and reasonably performant DAC and ADC onboard, a comfortable C library, a UPDI online debug interface, vendor support and thorough documentation in English? The ATTiny may be for you, or maybe you want an MSP430 or Cortex-M0, or maybe you want to spend $1 more per unit (worth 200 man-weeks of developer frustration in the paragraph above!) and get something with 10x the Flash and pin count.

A good comparison of some similar microcontrollers (including the ATtiny 1-series) written in 2017 is here:

https://jaycarlson.net/microcontrollers/

Note that this article was specifically tailored to parts just barely under $1, and didn't focus on the very cheapest parts.

HN has hosted discussion of this article some 4 times in the past 5 years, originally here:

https://news.ycombinator.com/item?id=15633785

We've gotten to the point where a small 32-bit ARM core IC is cheaper than an 8-bit atmel core IC. I've stopped using 8-bit chips entirely in my designs.

> a small 32-bit ARM core IC is cheaper

Can you show an example.

stm32g0 parts (for example the stm32g030) can often be in the <$1 range, or <$0.50 at decent quantities. I think there is even an stm32c0 line planned at a lower price point.

There are likely lower cost parts, but the REALLY cheap 32 bit parts are moving to RISC-V, see WCH's recent releases.

Edit: as a specific example, the STM32G030F6P6TR is available at $0.74 for one, or $0.45/ea at qty 1000 over on JLCPCB's part list:

https://jlcpcb.com/partdetail/Stmicroelectronics-STM32G030F6...

I put some of these on a very recent project.

Here are ~200 examples from Digikey (sort by price->increasing at a reasonable quantity):

https://www.digikey.com/short/jjhtf0h8

These are Cortex-M0 and Cortex-M23 parts in manufacturer lines like Atmel SAMD10, Freescale KE04, Nuvoton Mini55, NXP LPC82x, Infineon PSOC4, STmicro STM32G0 and STM32F0, and others. And they often blow the 8-bit parts out of the water in features and performance, usually losing only in battery leakage current/active current consumption.

Technically they're often 16/32-bit ARM Thumb cores, not sure I'd call them 32-bit cores when 90% of the instructions you'll execute are 16 bits, even though the memory space and registers are 32 bits wide. I suppose they feel close enough to developers and users like 32 bit cores as opposed to something that's painfully, obviously, only 8 or 16 bits wide that you can just ignore that technicality...

fwiw: cortex-m parts would be pretty conclusively referred to as 32-bit parts (due to the 32-bit address space/pointers as well as 32-bits being the native word size of the platform).

Other 32 and 64 bit platforms support some kind of "compressed instruction" support, for example 32-bit ARMv7 microprocessors (think early android phones, original raspberry pi, etc.) also support the 16-bit Thumbv2 instruction mode, though thumbv2 support was removed in AArch64/ARMv8.

This is contrasted with a "true" 16-bit platform like msp430, which has 16-bit pointers and native 16-bit words.

RISC-V also has an optional compressed instruction set for both 32- and 64-bit platforms as well.

And the Xtensa LX6/LX7 use a compressed 24-bit instruction set, but are referred to as 32-bit chips, just to add to your overall point.

I agree, I think it's strange to make the instruction encoding influence whether or not a part is to be considered 32-bit.

Instead I think the programmer's model is what determines that (which would make these ARM cores firmly 32-bit like you say).

I wonder if that's because the lower power consumption of an 8 bit Atmel is now in itself a premium feature consumers think is worth paying for? Definitely useful for remote IoT nodes at the very edge, where battery life really matters.

The prices listed in the article are for buying a single chip. If you're buying in the thousands by the reel, many suppliers will sell you them for less than half the one-off price.

5V compatibility and 40mA per pin has associated costs. You won't get that in a cheap ARM device.

That can save a dollar on other parts

That's mostly effect of production node. Smaller transistors get you better uA/MHz but lower currents (unless manufacturer just decides to spend more die space on output transistors) and lower running voltage

Less than $0.34 in volume[1]

1: https://www.microchipdirect.com/product/ATTINY402-SSZT-VAO?p...

Yes, they are expensive. This is what prompted a lot of people to switch to alternatives like Padauk. They had supply issues, though :/

And most of the padauk chips hobbyists bought are collecting dust.

Partly.

There is a lot of people who buy these in very small quantities, myself included.

Bulk purchasers pay much less. The ratio of cost of single unit when buying one and a huge amount varies wildly from chip to chip.

Atmel were always bit pricy for the featureset

Which (comparable) ones are cheaper?

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