AVR Freaks

Already on the list! Cute little part!

Ugh. You're killing me, Atmel. It was hard enough for me to get that AVR Dragon up and running. I'll order one of those Xplained boards for the 817 — that supports debugging, right?

By the way, this ATtiny161x is a beast. I can't wait to get mine in the mail to play with! 

It has a strange resemblance in density and peripheral selection to some of the higher-end EFM8 parts from Silicon Labs (16K flash/2K RAM, 20-24 ADC channels, three DACs, configurable logic block, timer configuration, etc). I wonder if it was designed to be a direct competitor? Anyone know the scoop on this new part?

Yes, but for everything other than weirdo projects^​1, "time precision" really means "a good RTC" — typically, once you're in active mode running on the main oscillator, you don't care how fast you're running; just as long as it's as fast as possible, so you can get your work done as quickly as possible and go back into sleep mode. The new Tinys have finally caught up with everyone else in that they have an internal 1%-ish RC oscillator that can run the chip at full-speed.

The New Tinys look good peripheral-wise, but I was really disappointed that they still have crazy-high active-mode current (10 mA??). Hopefully Microchip/Atmel will get a core internal regulator into their design sometime soon, otherwise it's going to get eaten alive in power benchmarks compared to.... well, everyone else. It's good to see standby power consumption with the RTC running in the 700 nA range, though.

¹ I recently required a very precise 48 MHz time base for some ultrasonic wind measurement time-of-flight work.

All of those things, balanced equally, under $1. In other words, a modern, general-purpose, 16-32 pin MCU that you would drop in entry-range, current-generation products. If you look at my list of other controllers I've selected thus far, that means 3.3V, internal oscillator, low active current, lots of timers, 10-14 bit ADC with tons of channels, 6+ PWM channels, 8-16 K of flash, 1K+ of RAM, one or more UART/SPI/I2c modules, and maybe some secret sauce — programmable logic, waveform generators, DACs, etc.

@gchapman pointed me to the ATTiny1616, which I think I'm essentially settled on as the AVR representative for this round-up I'm doing. Unless you've got an alternative idea?

Sounds like now the discussion is moving onto other non-AVR parts to consider — which I'm totally open to!

This is abundantly obvious.

Yup, same as many of us.

It's miraculous that in the last 20 years, compilers other than AVR-GCC have figured out how to meet these requirements.

Many do (NXP, Atmel, Nuvoton, etc). It's annoying. Give me a small break-out board I can put on my breadboard and get on with my life.

Arduino has shipped 4 or 5 million units total. Microchip ships a billion PICs a year. Go take apart things around your house. AVRs are rare to encounter, and if you do encounter one, it's probably not an ATMega328p. It would be a logical fallacy to conclude that they're consequently bad parts — but it certainly doesn't seem like Arduino/AVR is making much of a dent in the global MCU economy. I hand them out to all my non-engineer / artist friends, though, and their kids. They're groovy little boards if you want to build simple interactive projects.

I'd argue that a $25 dev board with a 16 MHz microcontroller and a USB-to-UART on it is over-hyped and ridiculous — but that's just me. 

I tried to be nice. When you stuck your head in this thread and wrote up your "ATMega is good enough, there's really no need for anything else" comment, I tried to be polite. But seriously, we're having a great discussion about current/new MCUs out there — I've been getting caught up on the AVR ecosystem by @gchapman (thanks!), and learning about all the stuff Nuvoton is doing, and really enjoying the conversation.

...but then you come in and start making racist comments about the Chinese and their products. I read a few of your other posts, and look, I'm sorry that the cheap TFT you bought on eBay was made in Shenzhen and not Chicago, but when you buy products from people who live in different countries than you do, language barriers are going to happen. We all deal with it. You could have dropped $70 at Newhaven Display's web site and chose to support an American company who might have supported you back, but you didn't go that route.

And instead of, you know, actually choosing a proper microcontroller to drive a 320x240 TFT (like one that actually has an LCD controller on it, perhaps?), you're trying to string together some random Arduino code you found on the internet with some random display you found on the internet, without investing in the time required to understand how these displays operate at the register level. And you're upset about the grammar in the datasheet!?

If you would ask for MCU recommendations in this thread instead of using it as a soapbox for your disparaging remarks about Chinese products, someone would have pointed you to an MCU that has a parallel RGB LCD interface, which is a much better way of driving large pixel-array displays (such as full-color 320x240 TFTs, like the ones you mentioned). Because these MCUs have LCD controllers built-in, you can use $4 "dumb" RGB displays; the only thing you need to look up in the datasheet is the timing parameters. It turns a display into a commodity product that can be easily swapped out. Higher-end Kinetis, LPC, and STM32 parts support it, along with I'm sure many others.

You've admitted you aren't up-to-date on anything we're talking about — why not use it as an opportunity to ask questions and listen?

The reason the mega328 isn't in the review is that it's more than $1. It's amazing how much it's come down in price: microchipDIRECT has the 328pb — which I agree is a substantial upgrade to its predecessor — for $1.05. But that's still more than $1. You can make fun of me, but the problem is as soon a I say $1.05 is OK, then I'll be looking at some great NXP part that's just 10 cents more, and then I really ought to swap out that PIC16 for a PIC24, and... blah blah blah. Plus, it's way more fun to try to squeeze as much out of the parametric searches as possible :-)

As for "being picky" literally *every other* microcontroller that I'm reviewing operates at full speed on 3.3V from an internal oscillator. I don't think I've ever had to lay down a random 20 MHz crystal on a board to drive an MCU before in my life. It's just sort of a weird, foreign concept. Should I include the price of the crystal when talking about the MCU price? What about package dimensions? Small crystals are really expensive. Or do I just test the mega with its fastest internal oscillator, as this is the configuration that most designs will use? 16 MHz, I think?

Voltage is another problem. The device I use for measuring really accurate current consumption only outputs 3.3V, which literally every other MCU plays fine with. Do I cobble together some other way to accurately measure current consumption — just to test this single part? Do I test it at 3.3V, which, again, I assume most designs will be using? (I can't think of the last commercial product I've designed or torn down that had a 5V MCU in it). I don't know — I'm still thinking about how to review the tinyAVR1616, because it's got the same voltage issues.

I'd be willing to evaluate a megaAVR (as long as it's $1 or cheaper), but I'd like input from you on how you would go about working through that stuff. Also, if I'm already reviewing a tiny1616, what's the point? Is the development process different? Is the core performance going to be substantially different? (not rhetorical questions — seriously, let me know, as I'm not knowledgeable about AVR).

For testing, I'm essentially doing four things: First, I'll measure speed and power consumption while running a 64-sample array through a second-order high-pass filter implemented as a 16-bit signed direct form I biquad (to test math and memory speed). I'll do a simple LED toggle (to illustrate the instruction cycle / system clock / number of instructions relationships — more just for fun, as it's not a serious way of measuring overall system performance, but it gives the reader intuition about the how the architecture works). Finally, I'm going to implement a DMX-512 receiver that controls an RGB LED, and measure active power consumption (so I can get a feel for the platform's code-generation tools / peripheral libraries, and to measure power consumption in an environment where you can't actually sleep the MCU, and instead just halt it). I'll also put the chip in deep sleep with an RTC running (if the MCU has it), just to collect similar data across all platforms at the same voltage (which is the annoying part about comparing MCU power consumption from their datasheets).

Big winners will be efficient architectures that can do a lot of math quickly (as well as with low active power consumption), as well as architectures that have very low idle current, and architectures that have very low sleep current.

Yeah! I love playing around with that stuff. I found some original 8751s (basically, 8051s with EPROM — not EEPROM) on eBay and wrote up a post on my new blog about developing and programming them with current-generation tools (Silicon Labs Simplicity Studio, modern USB-based EPROM programmers, etc). 

I was referring to AVR-GCC, not GCC in general. So other platforms' GCC implementations (ARM, MSP430, RL78), along with other open-source compilers, like SDCC (which is finally starting to get decent at 8051 and STM8 code, though from what a friend tells me, still struggles to produce good PIC code — haven't verified myself).

But the other thing is this: if you're a student, hobbyist, or a professional looking to evaluate an MCU, I think you'll be fine with the free "limited" compilers — no matter which platform you're using (ok, except Microchip if you want any semblance of performance). I know you're going to criticize me for calling expensive, proprietary, limited compilers "free" but effectively, they are. (We're talking free-as-in-beer, not open-source).

Take CC-RL, Renesas's in-house compiler for the RL-78, which I've been playing around with all weekend for the review. It produces absolutely fantastic code. Yes, after 60 days, it goes into code-size-limited mode — but the limit is 128 KB of linked code. That's almost comically high. I don't know about you, but I've never used that much code on an 8-bit MCU before in my entire life, and probably never would.

A lot of these ARM MCUs on my list are pretty weak in terms of flash (the PSoC 4000S has 16K, but everything else is running 8). Need a good, efficient compiler for an 8 KB part? Go download a free version of MDK, which, by many measures is the absolute best ARM compiler for microcontrollers. It's code-size-limited to 32K, but who cares? If you're buying a 64K or a 128K part, you can probably switch back over to ARM-GCC and have enough headroom to lose a bit of efficiency.

Also, keep in mind that many semiconductor houses work with compiler vendors to provide free versions of them to their users. The best STM8 compiler on the planet, Cosmic, is now totally free and unrestricted. Silicon Labs gives away full versions of Keil C51 ​with Simplicity Studio and — you didn't hear it from me — it can be used to compile code for any 8051 (useful if you're a hobbyist and don't mind skirting under the EULA to squeeze in a bit of extra code).

The other thing is cross-platform support. I'm on Windows, but if I wasn't, I'd probably be much more comfortable with Silicon Labs or an ARM vendor, since they all provide officially supported macOS and Linux builds of their entire products. Sure, you can easily setup an AVR toolchain to build code on macOS or Linux, but with no IDE and no debugging support, it's not a viable option for the general professional market (we're lazy).

I looked at the HT66F0025, and it's... well, it's cute, but I wouldn't call it a general-purpose MCU. 

Instead, I found a bunch of HT66F0185s on Taobao for 30 cents in single quantities. These guys are in a 28-pin SOP package with an integrated 16 MHz oscillator, 8K of flash (4K x 16), and 256 bytes of RAM, with 128 bytes of EEPROM. 8-channel, 12-bit ADC, UART/SPI/I2c. Three timer channels. Seems much more general-purpose to me.

You scared me with the datasheet comment, but I actually find the datasheet for this guy perfectly readable. Of course, I'll be regretting this comment when I start programming these chips and find a bunch of errors.

I always read the timers section of a datasheet first — if I can understand your MCU's timers, everything else is smooth sailing.

They guarantee a flash program memory retention of >10 years. Hey, at least they're not overselling this thing.

It looks like I'll need to actually buy the HT66V0185 emulator chips, and hook them up to an e-Link debugger. I found both of those on Taobao, too. Looks like the emulator chips are going to be about $2.22 each, which is more than I'd expect. the e-Link debugger is $48.

Is there a better place to buy this stuff, @jgmdesign?

Or do I just test the mega with its fastest internal oscillator

Definitely agree with you on mice and other commodity products with really really cheap MCUs in them. Good 1% on-chip oscillators are expensive to make and calibrate, so it makes sense. All USB micros used to need external crystals, but now all the $0.75+ USB micros do crystal-less designs by PLLing from the USB D+/D- signals — lets the USB port on your computer generate the clock. Brilliant. The CH340 and other cheapo USB peripheral chips still use crystals though. Other, non-USB cheap MCUs? Idk... seems like most of them are crystal-less, too. I think everything you're saying was dead-on... 5-10 years ago. But $1 buys you a lot of microcontroller these days.

I mean, $1 isn't going to buy you a 144-pin beast, but most of these chips I've listed are 24-32 pin. The STC15W is the monster — 40-pin PDIP (with 61K of flash! $0.88!)

I think the Freescale KE04, Tiny1616, and SAM D10 are the smallest at 20 pins.

Definitely no 8-pin doodads.

Agreed with the "inaccurately" — I've run 1 Mbps UARTs with 1% on-chip oscillators without issues. Well, without "too many" issues...

Yup, good point. They all run at 3.3V with their internal oscillator.

Yup, RTCs and RF are the two exceptions I see all the time and design with myself.

I'm glad you mentioned time-keeping, because RTCs are actually one of the reasons why I shy away from MCUs without good, full-speed internal oscillators. Since most general-purpose MCUs only have one crystal input, you're sort of up a creek if you need precise time-keeping if you're using something that doesn't have a full-speed internal oscillator or a PLL/FLL. Sure, you can hook up an RTC to your crystal input (I assume?), but when you wake up from an RTC event, you'll be running at 8 MHz instead of 20 MHz. At best, it's just going to drain your battery faster (maybe not an issue for your application). At worst, it isn't going to be able to run your code fast enough to do whatever it's supposed to be doing.

I bet you that in many applications, neither of these is an issue. But the whole point of this review is to provide exposure to a wide range of MCUs, and point out some trends. 

At the most basic level, I want to help people develop some intuition when they ask themselves "What can I get for a buck?" — and, because I'm involved in education — "I know Arduino. Now what should I learn?"

Alright, I'm planning on setting up the Tiny1616 code tonight in Atmel Studio. It's my understanding that ASF only supports megaAVR and ARM parts. What's Atmel's recommended peripheral library to use? Is there a code generator tool for peripheral initialization I should be using? Searching the Google didn't immediately yield anything, so any recommendations are appreciated!

Neat -- I'll throw it into the mix since there appears to be a lot of interest.

Yeah, maybe it's just me, but I feel like reading "16-bit second-order filtering at 400 kHz" gives me better intuition for how powerful a processor is.

I don't think I want to get into a compiler review scenario, so I'll stick with the manufacturer-supplied toolchains. Maybe I'll play with EWAVR a bit. Is this more commonly used by professionals than Atmel Studio? Sorry, I really don't know this architecture very well at all.

@gchapman, I have to sincerely thank you for taking so much time to walk me through everything and provide links to most everything you mention. I'm new here, but I'm quickly wishing there were more people like you on the other forums I visit.

When I had my wisdom teeth taken out and I was jacked up on hydro, laying in bed with my laptop, bored out of my mind, I set up an account. The most annoying thing about Taobao is it's a little "too secure" — your account has to be linked to a mobile phone number, and they'll do a 2-factor authentication whenever you sign in on a new device.

Go through https://world.taobao.com/ — it seems to be the site you can use when you want to ship stuff out of the mainland. Tips:

• Use Google Chrome's built-in page-translation capabilities. You'll feel like you're on eBay or Ali Express. Seriously, it's uncanny. I often forget if I'm on Taobao or Ali Express (that is, until I look at the prices...)
• The hardest part is setting up an account. Lots of javascript-based pop-ups you have to fill out that Google Translate doesn't pick up on. At one point, I had to find "United States" (美国) in a list of countries. They were alphabetized, but... well, I don't speak Chinese.
• If you can't select text to paste into https://translate.google.com (like a hint in a text field, for example), hit F12 to pull up the developer console, find the HTML, and select the text that way.
• When you find something to buy and you click "Add to Cart" nothing will happen — you always have to click the "the country" pop-down by the originating location, and choose "overseas" before the javascript will let you click the "Add to Cart" button.

This all seems moderately insane, but after you spend an hour doing it, you'll have access to an amazing resource to buy stuff.

• Taobao uses shipping consignment companies, which is awesome. Let's say you buy 10 different items from various vendors on Taobao. Instead of paying EACH of those to ship overseas, you actually pay local postage (<$1) to ship them to these consignment warehouses, which then package stuff up and ship it to you in one box. It takes longer, and it's a two-step purchase process, but it's cheaper. By the way, it really is a two-step process. Once the items arrive at the warehouse, I think you only have 10 days ship them. So it's annoying if you're waiting on an item or two to ship. make sure you login and keep track of that stuff, because after 10 days, I think they either start charging fees, or send the items back to the seller.
• It looks like most sellers offer direct shipping, too. You can check the "Ask the seller to ship" checkbox when submitting payment, and write a little note with your address. Again, seems sketchy, but these people really do work hard to make things right. One guy kept the fast EMS shipping — overseas — and didn't charge more for shipping. I felt kind of bad.
• Taobao is operated by Alibaba, which is equivalent in size, scope, and corporate stewardship to eBay. If you trust eBay, you should trust Taobao.
• All financial transactions go through Alipay (Alibaba's PayPal equivalent), and it works similarly to eBay or Ali Express.
• The site has a wayyyy better selection of silicon than AliExpress does, and the site allows partial string searches, which is amazing for us electronics folks. "STC15W" on AliExpress only turns up three hits — if you wanted to find some STC15W parts, you'd have to iterate through all of the different part numbers. On Taobao, "STC15W" yields 86 pages (yes, pages) of results.

Haha, this thread has gone off-track a few times (which led to some great discussions), but just to clarify: I'm talking about $1 or less, shipped from a major U.S.-based distributor (something you'd find on Octopart), or directly from the manufacturer in quantities of 100. Newark has crazy sales and close-out specials all the time that I'm not considering, nor am I considering Taobao prices. That was just for fun.

So yeah, I totally agree with you. I play around on Taobao not because of the prices (who cares? we're talking about paying 30 cents instead of 80 cents), but just for fun — and also for access to East Asia ICs that I don't otherwise have any access to.

STC is a great example of a huge manufacturer of 8051 MCUs that have a totally reasonable, hobbyist-friendly development path (free Keil or SDCC download, USB-to-serial converter for programming and debugging, decent English datasheets, and 23749283472938472 different web sites out there with 8051 samples). But it's tough to find STC parts outside of Taobao / Ali Express. 

Oh, totally. If I'm building one-offs, I'd have no problems paying for a $5 or $10 MCU. But:

• MCUs that can do everything (popular example is the STM32F4) are complicated to configure, use, and lay down on a board.
• There are a ton of $1 MCUs that I'd say can do "about anything" that are also *really* easy to use. 

I think the disconnect is that some people on this thread have it stuck in their brains that cheap MCUs from lesser-known brands must be really unfriendly to use, as they're not popular among hobbyists. But in my testing so far, I've actually found the opposite to be true. As an example, I had never touched a Renesas part in my life before last weekend, and I had an entire DMX-512 RGB LED project built from start to finish in about fifteen minutes.

Modern code-gen tools and well-documented peripheral libraries, coupled with the fact that most manufacturers are going to Eclipse-based IDEs means that it's super simple to jump around between architectures. I'm talking, like, an hour's worth of work to skim through the datasheet, download the tools, and get stuff set up before you can start your project. It's insane. Anyway, that's what sparked this whole quest in the first place.