A newbie exploring MCU's

[casper.bang]

After gradually finding my way back into electronics (hobby) since my teen years, I've noticed many differences; TTL levels are now down to 1.8V, SMT is now within the realm of hobbyists and not the least discrete and TTL/CMOS gate schematics are being replaced by cheap micro-controllers.

Being a software guy, I'm not so scared off by the compiler element as I am by the complete process part (are there open source compilers?, which architecture/platform?, how many times can they be reprogrammed?, which programming adaptor to use? what are the prerequisites?).

Could a kind soul perhaps guide me in some direction such as best starter kit and/or resources which could help a noob like me get a feel for this new MCU world? I don't really have any specific requirements, apart from cheap/small/easy and A/D would be nice too. I kind of like the simplicity of some of the low-pin 8bit stuff I find, such as the PIC10F204T and PIC12CE67X.

[Kremmen]

As you no doubt have noticed - or are about to - there is no one answer.  On a high level, there is the division into "high end" 32 bit MCUs, typically ARMs but there are others, and the "low end" 8 bit ones where PIC and AVR rule. You will get all kinds of recommendations - mine is AVR if only because that is what i have "standardized" for myself. Some reasons why AVR (and they may be applicable to other choices as well):
- Good free/open toolchain based on the GNU compiler collection.
- The internal architecture of AVRs is a good match to the logic of C compilers.
- Really easy to install free uncrippled IDE available from Atmel (Studio 6) covering practically all Atmel MCUs. I lose patience with the open source tools where you need to make it a separate tinkering project to get a line of source compiled and debugged. With Studio it all works out of the box as nature intended. Actually i am typing this on a laptop where i just installed Studio 6 and started compiling as quickly as the machine was able to install the package. Zero tweaking and tinkering. Big plus to Atmel.
- AVR MCUs are very well documented with proper datasheets and numerous appnotes.
- Cheap programmers and other tools are available from multiple sources.
- The AVRFreaks forum is a big help in practical questions of all kinds.

Being a software guy, I'm not exactly scared off by the compiler element as much as I find it daunting to figure out how the programming is carried out (are there open source compilers?, which architecture/platform?, how many times can they be reprogrammed?, which programming adaptor to use? what are the prerequisites?).

For AVRs:
-Studio 6 for all development tasks; source editing, build, simulate, program, debug.
-there are many adapters depending what you need. Things like Atmel's AVRISP or the open source AVRdude + parallel port let you program chips but for in-circuit debugging you need something like a JTAGICE mk II or 3, either a genuine one from Atmel, or a copy.

I don't know if there is any other chip family where you get up to speed as easily and with as easy to use toolchain. But opinions may vary.

[Bloch]

(are there open source compilers?, which architecture/platform?, how many times can they be reprogrammed?, which programming adaptor to use? what are the prerequisites?).

• There are free compilers for Microchip  (not sure about the open source compilers)
• 10000 erase/write cycles
• Pickit2 for programming

I kind of like the simplicity of some of the low-pin 8bit stuff I find, such as the PIC10F204T and PIC12CE67X.

http://www.microchip.com/pickit2 will do great for you then. Later you can upgrade to other tools.


Also take a look here http://dangerousprototypes.com/docs/PIC_12F/16F/18F_quick_start

[Paul Price]

There is a lot of people that have been playing around with the 16F876A because it relatively simple and you can download the HTC pro ver. 9.83 C-compiler for the PICC 10/12/16 series of chips. free from MIcrochip.com that does a fine job compiling. The 16F886 replaces the 16F876A and is a very close replacement that costs about half as much,  about $3.50 US. This chip has comparators, UART, 8-bit timers, 16-bit timer, two PWM outputs, 10-bit A2D with 5 A2D inputs. It is amazing what can be done with <400 bytes of RAM and 8K of program memory.

The 16F1786 is a very new chip that has a built-in 1% accurate 32MHz osc, more RAM and program space, and both 12 bit A2D and D2A converters, a built in op-amp, comparators,  8-bit timers, a 16-bit timer, PWM outputs,  UART and plenty of pins for Iinput/Output. Problem with this very new chip is that you have to purchase a PRO version of the XC8 compiler for the compiler to work well with any chip and that means $!00's of bucks.

The are many projects downloadable from the web using the 16F876A, even some good ones from YouTube.

Because this chip is available in a DIP 28 or skinny 40pin  DIP package it is very easy to just plug into a breadboard, add 5V power supply wires and a 20-MHz crystal a resistor on the reset pin and you have a working MCU.  Cheap programmers are available on the net on ebay that use USB interface. I made my own programmer that is lightening fast using the parallel port of my Windows PC and that works from DOS. I wrote the software to program this chip and a few others. I downloaded the programming guide from Microchip for the 16F886, 16F887, 16F876A, 16F1786 chips and used that info to write my own program to program chips.

You can write your source code in DOS with Edit  and then feed this to the compiler and you get a hex file out  to program the MCU

Although I use DOS tools to compose, compile and debug some of my projects, there are Windows IDE's free from Microhip and other Windows IDE's as well as many USB programmers/debuggers that some might find cheap and easy to use.

For example, Mikro-C has a compiler/IDE, 2-K program code limitationwith the free version of their compiler and free IDE, works with their USB programmer.

I monitor the operation and debug my MCU projects by using just one pin of the MCU for serial transmission and use the antique but very usable DOS QBasic programmed to display var values that are sent  to my PC for debugging and monitoring.  A subroutine in my source code transmits every var. value I am interested in using the serial port at 19200 baud at a refresh interval I select.

There are plenty of USB dirt-cheap programmers for the PICC chips on ebay: http://www.ebay.co.uk/sch/i.html?_sop=15&_sacat=0&_from=R40&_nkw=pic+programmer&LH_PrefLoc=2&_nkwusc=picc+programmer&_rdc=1

http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=pic+programmer&_nkwusc=picc+programmer&_rdc=1


The MCU's I like working with are available in 28 and 40 pin DIP packages, this means all I need is a solderless bread board to very quickly wire together some MCU idea. And this also means the same chips can be used over and over again.



The open source compilers are rather difficult to use, have limited repertoire of chips, difficult to debug your source code with.

[Dave]

Another vote for the AVR. The software is free, reliable and simple to use, programmers are dirt cheap on eBay and the AVRs themselves aren't expensive either. They offer quite a lot of bang per buck, you have lots of useful peripherals inside, extensive set of processor instructions (most of them executing in a single clock cycle) and they don't require much external circuitry. The datasheets are very well written, too.
But most of all, they are very simple and straightforward to use. As mentioned above, if you get stuck, you always have the excellent avrfreaks community there to help.

[casper.bang]

@Bloch:
Those are very clear and direct answers, making me 99% ready to press the order button for a KIT and some PIC's. Also, the quick start you refer to makes it look very digestible, my main scare now is how great the Linux support is.

@Kremmen, @Dave:
AVR (had to Google what that actually stands for) seems a little bit more niche, only because I don't know which ATtiny would match the 8bit low-pin PIC's I have my eyes on. However, the software tool chain argument weighs heavily so perhaps I need to give the AVR another look.

@Paul Price: Those PIC's sure look fun and capable, but perhaps a bit much for me to cut my teeth on. And wow, it's not often you find people referencing DOS and QBasic in this day and age; personally I miss neither one I must say.

I think I'll let people chime in a day or two on this topic, before committing to an architecture.   

PS: Interesting comparison: http://www.ladyada.net/library/picvsavr.html

[Dave]

If you want an absolutely tiny (SOT23-6) microcontroller, go for ATtiny4, 5, 9, or 10 (basically the same, slightly different specs and functionality). But bear in mind, that these four are not programmed by ISP (In-circuit Serial Programmer), but rather by TPI (Tiny Programming Interface), so not every cheapie programmer from eBay supports them. You can, however, get another programmer which supports ISP, TPI and PDI (Program and Debug Interface - this one is used for programming ATxmega chips). I have it, very satisfied with it.

Another replacement for the smaller PICs would be ATtiny13 (8-pin device), or if you need a bit more kick ATtiny25, 45 or 85 (essentially the same chips, just different flash sizes).
If you need more pins, ATtiny2313 would be appropriate.
These chips (13, 25, 45, 85 and 2313) all support ISP, so any cheap AVR programmer will do.

If you need anything bigger, you can go for the Mega family (ATmega8 is a very popular choice - you will find lots of tutorials for this chip online).

One major advantage of AVRs over PICs is that AVR offers 1 instruction cycle per clock cycle, as opposed to 1 instruction cycle for 4 clock cycles on the PIC. The AVR is essentially works 4 times faster than a PIC with the same quartz crystal.

______
On an unrelated note, this is my 100th post on this forum.

[Kremmen]

Oh AVRs are anything but niche, one of the most common MCUs out there. You can find them inside practically anything.
I don't know about matching PICs, that has never been an issue for me, but there are AVRs from the microscopic ATtiny10 in 6 pin SOT23-6 package to the popular ATMega328 (powering Arduino among other things) to larger Mega's and after that the semi 16 bit XMega series and finally the 32 bit UC32 series, with same toolchain for them all and Atmel SW Framework for most.

All your original questions and more are answered at http://www.atmel.com/products/microcontrollers/avr/default.aspx and http://www.atmel.com/tools/ATMELSTUDIO.aspx

[Bloch]

@Dave


There are the simple / easy to start / cheap ? in AVR ?


The Pickit is a 1 step and you are ready to code !

• Unpack the Pickit
• install the software on the cd
• plug the Pickit into the included demo board
• Download demo code to demo board it cant been easier....

With AVR why do he have to buy a cheap cheap programmer and it seams there are different types ...... not easy for a beginner.


<Rant> "The AVR is essentially works 4 times faster than a PIC with the same quartz crystal. "  Why do i use time on this  </Rant>


@casper.bang why did you not mentioned LINUX in the first post    But then you are in the 0.001% of the crowd it don't get easy-er. I have no idear how it is to program MCU´s on a Linux PC 

[casper.bang]

@casper.bang why did you not mentioned LINUX in the first post    But then you are in the 0.001% of the crowd it don't get easy-er. I have no idear how it is to program MCU´s on a Linux PC 

Yeah I probably should have, but I figured I could get far with Wine or VirtualBox if it came to that. However, native support from my OS in the form of IDE etc. is obviously a bonus.

I start to understand this is yet another religious debate with no one right answer. PIC really does feel more KISS (keep it simply stupid) to me, but toolchain and community matters as well.

Just found out Dave Jones also has a thing or two to say about this topic:

[Kremmen]

@Dave


There are the simple / easy to start / cheap ? in AVR ?


The Pickit is a 1 step and you are ready to code !

• Unpack the Pickit
• install the software on the cd
• plug the Pickit into the included demo board
• Download demo code to demo board it cant been easier....

With AVR why do he have to buy a cheap cheap programmer and it seams there are different types ...... not easy for a beginner.


<Rant> "The AVR is essentially works 4 times faster than a PIC with the same quartz crystal. "  Why do i use time on this  </Rant>


@casper.bang why did you not mentioned LINUX in the first post    But then you are in the 0.001% of the crowd it don't get easy-er. I have no idear how it is to program MCU´s on a Linux PC 

Ah but you are talking about kits - the others are talking about MCUs.
If a kit is all you want then grab an Arduino - won't get easier than that.
However, once you have designed an original circuit and included an MCU, you then do need a way to program and debug it. All of that you can do with AVRs and never leave the Studio.

[Dave]

Haha, I knew I would offend at least one PIC fanboy by pointing out that it's 4 times slower than an AVR.

With AVR why do he have to buy a cheap cheap programmer and it seams there are different types ...... not easy for a beginner.

What's so difficult about picking up the cheapest programmer on eBay that's advertised for AVRs? If that's difficult for you, I'd really hate to see you struggle with blinking an LED.

[madires]

@Bloch:
Those are very clear and direct answers, making me 99% ready to press the order button for a KIT and some PIC's. Also, the quick start you refer to makes it look very digestible, my main scare now is how great the Linux support is.

I'm happily AVRing with Linux, avr-gcc and avrdude for the software side and BusPirate as ISP programmer. There are tons of other inexpensive programmers supported by avrdude. IIRC the AVR Dragon also does HV parallel programming (required if you mess up the buse bits :-).

[mariush]

I went with PIC simply because I wanted a bigger "challenge" (to learn architecture and write asm or c closer to chip) and didn't want to get lazy and end up with arduino and sketches (basically an atmega with firmware in it, and you write some stupidified c that gets compiled into c or asm and uploaded into arduino)

Yeah, in theory it takes 4 cycles to do an instruction on a pic but it's not so cut and dry as the expression says - the attiny and whatever don't do one instruction per cycle, it varies, so they don't get 4 time the speed. Also you often get chips capable of running at higher clock speeds while the atmels are limited, so you can sort of make up in speed by raising clock (and waste a few more mWatts).

From what I noticed, PICs especially on the cheaper end or on the low pin count are more versatile (pack more hardware options) and often have integrated 20-24-32 mhz oscillator with reasonably good accuracy, while a lot of people say the built in oscillators on the atmel chips are junk and that you basically need external oscillator to do anything. I haven't tested it personally so I couldn't say, I found the internal oscillator in pic16's to be good enough for me.

With PICs you have a bigger initial investment - you kinda have to buy either pickit2 or pickit3 but then the programmer (pickit3) will work with any chip. pickit2 can't do some of the newest chips. There are clones on the market but I'm not sure how reliable they are.

[Paul Price]

Mariush:  The newest chips, like the PICC 1786 have a built in 32MHz clock, so they are 1 1/2 faster than the 16F886 type, for example, and the clock is accurate to 1% and also low power use at all clock speeds.

[Dave]

I went with PIC simply because I wanted a bigger "challenge" (to learn architecture and write asm or c closer to chip) and didn't want to get lazy and end up with arduino and sketches (basically an atmega with firmware in it, and you write some stupidified c that gets compiled into c or asm and uploaded into arduino)

You do realize, that we are talking about pure AVR C code here, not stupified arduino crap?
I have also programmed AVRs in assembly (in fact, my latest project uses asm only) and guess what, you can do that, too. Amazing, isn't it?

Yeah, in theory it takes 4 cycles to do an instruction on a pic but it's not so cut and dry as the expression says - the attiny and whatever don't do one instruction per cycle, it varies, so they don't get 4 time the speed. Also you often get chips capable of running at higher clock speeds while the atmels are limited, so you can sort of make up in speed by raising clock (and waste a few more mWatts).

Take a look at ATmega8 datasheet, page 302. You can see most instructions take 1 or 2 cycles, very few take up to 3, and only 2 branch instruction go up to 4. Now let's have a look at PIC16F1786 datasheet, page 379. Most instructions take 1 instruction cycle (4 clock cycles), all the control intructions (branch would be Atmel's equivalent) take 2 cycles (8 clock cyc.). Now compare the two.
So, top PICs go up to 32MHz (8MIPS), top AVRs go to 20MHz(20MIPS). AVR still wins.

From what I noticed, PICs especially on the cheaper end or on the low pin count are more versatile (pack more hardware options) and often have integrated 20-24-32 mhz oscillator with reasonably good accuracy, while a lot of people say the built in oscillators on the atmel chips are junk and that you basically need external oscillator to do anything. I haven't tested it personally so I couldn't say, I found the internal oscillator in pic16's to be good enough for me.

The internal oscillator directly from the factory are supposed to be accurate to 3% and you can calibrate the oscillator to 1%. As Paul Price states, this spec matches the one of the PIC. Of course, if your timing is critical (communication for example), you should use an external crystal or oscillator, but for other things, the internal oscillator is good enough.

[jucole]

One of the great things about Microcontrollers is there is a workflow to suit everybody.  I'm only a hobbyist, but I went with PIC; the main reason was because I felt Arduino wasn't as challenging as taking a single PIC chip and then building something completely from scratch.  It doesn't get more fun than creating your very own bit-bashing UART and I2C and debugging libraries etc.    At the moment I've moved to FPGA's and verilog,  but all that hard work with the PIC is really helping me with my big new project.   I'd like to try Arduino at some point but I just haven't got to it yet.

[mariush]

You do realize, that we are talking about pure AVR C code here, not stupified arduino crap?
I have also programmed AVRs in assembly (in fact, my latest project uses asm only) and guess what, you can do that, too. Amazing, isn't it?

What I mean is that by going the PIC route, I'm forcing myself to actually learn stuff better. I tend to find workarounds and shortcuts and that's what I mean by becoming lazy and going the arduino route. I want to code the libraries myself, to learn about the hardware, not just write a one liner in an arduino sketch, even though it's tempting because it's easy and fast.
Besides, pic is different and seems more interesting compared to avr, i could have gone with 8051 mcus just as well as avrs and it wouldn't have made any difference.

Take a look at ATmega8 datasheet, page 302. You can see most instructions take 1 or 2 cycles,

I never said at* are slower than pics, i agree they have more processing power but in real world the difference is not quite that big. 

The observation was more about the lower end, like I wrote.  atmega8 is a 2-3.5$, not a 0.5-1$ one.

Anyway, it doesn't really matter, no point to start a fight here about mcus. Pick one, you can always try the other if you want to later on.

[madires]

What I mean is that by going the PIC route, I'm forcing myself to actually learn stuff better. I tend to find workarounds and shortcuts and that's what I mean by becoming lazy and going the arduino route. I want to code the libraries myself, to learn about the hardware, not just write a one liner in an arduino sketch, even though it's tempting because it's easy and fast.

If you take the arduino just as a hardware platform you can do everything youself, doesn't matter if it's assember, C or C++. With the arduino IDE and the included libs a beginner is able to start the esay way. He'll have success quite fast and don't need to become frustrated over debugging for days. If he managed a few sketches he can proceed with avr-gcc directly and become a guru :-)

[Dave]

Anyway, it doesn't really matter, no point to start a fight here about mcus. Pick one, you can always try the other if you want to later on.

I didn't mean to start a fight, either. I apologize if it appeared so.
To be honest, if you are going to do anything more complex with a microcontroller, you are probably going to switch to ARM, since they offer far superior processing power, more peripherals and are generally cheaper than comparable AVRs and PICs.

[stev.dk]

As a beginner in MCU's, but with experience in programming, i started by getting a cheap-ass e-bay ISP programmer, and an AVR (Atmega32)... It might be a two step process, cause i got the programmer and chip separately (one step if theres a seller providing both). I dont count downloading the free software as a step really, cause you should really always download the newest version, no matter if its free or not.

I've been very happy with it. I like the AVR software, and it is as good as any programming texteditor i've worked with. Im not fanboy or expert in the capabilitys of the avr or pic mcu's, but comming from a programmer background, i can recommend this 

[casper.bang]

Fanboy talk aside and more practical concerns in context; I'm disappointed that Atmel Studio is a (giant) Windows-only application. Also, ATtiny10 does not seem easy to program i.e. not possible with even the popular Dragon and also not listed as supported by AVRISP mkII. Meanwhile, it was a snap to download and Install cross-platform toolchain and IDE (MPLAB-X, clearly based on Java and the NetBeans IDE) for PIC. So unless I am wrong about this or discover anything groundbreaking, I think I'm just gonna get the PicKit2.

[madires]

Fanboy talk aside and more practical concerns in context; I'm disappointed that Atmel Studio is a (giant) Windows-only application. Also, ATtiny10 does not seem easy to program i.e. not possible with even the popular Dragon and also not listed as supported by AVRISP mkII. Meanwhile, it was a snap to download and Install cross-platform toolchain and IDE (MPLAB-X, clearly based on Java and the NetBeans IDE) for PIC. So unless I am wrong about this or discover anything groundbreaking, I think I'm just gonna get the PicKit2.

The ATtiny10 is not programmed via the ISP as most other ATtiny or ATmega MCUs. It uses TPI which is some kind of stripped down SPI. TPI is supported by the buspirate.

[stev.dk]

Fanboy talk aside and more practical concerns in context; I'm disappointed that Atmel Studio is a (giant) Windows-only application. Also, ATtiny10 does not seem easy to program i.e. not possible with even the popular Dragon and also not listed as supported by AVRISP mkII. Meanwhile, it was a snap to download and Install cross-platform toolchain and IDE (MPLAB-X, clearly based on Java and the NetBeans IDE) for PIC. So unless I am wrong about this or discover anything groundbreaking, I think I'm just gonna get the PicKit2.

Im running AVR Studio on my macbook pro, and a friend of mine is running it in ubuntu.

I gave about 10$ for a ISP programmer, that programs all the ATtiny and ATmegas. I followed along some of these tutorials, just to get a basic understanding, not to brick my first mcu.

https://www.youtube.com/playlist?list=PLE72E4CFE73BD1DE1

[casper.bang]

According to what I can dig up, the attiny10 are program med via TPI.