Hacker News Reader

Hacker News

Comment by acqq | Hacker News Reader

Parent Full thread

acqq

ARM Cortex M0+ processor specs:

http://www.arm.com/products/processors/cortex-m/cortex-m0plu...

Advantages over 8-bit and 16-bit processors for embedded solutions, according to ARM:

http://www.arm.com/products/processors/cortex-m/cortex-m0plu...

View on HN

Interesting that they only make comparisons with PIC and 8051. AVR still blows them away on many angles; particularly energy efficiency, community, ease of use on not-windows, and price. (MSP430 too, for efficiency and price.)

I'm fooling around with the lower power ARM chips on weekends, and they seem like a great option when you really want to shoehorn in a full operating system somewhere.

Can you please write a word or two what you see as an advantage of AVR? I admit I don't have any experience but I'd really like to know. Thanks.

For other readers, AVR:

http://www.atmel.com/products/microcontrollers/avr/default.a...

From an engineer's perspective, the AVR 8-bit instruction set is far nicer to work with than the 8-bit PIC. It's been a few years since I've been an embedded electronics engineer, but I seem to recall PIC not having an easy way to implement a stack, and hence a (proprietary) compiler which didn't support reentrant functions.

AVR OTOH has instructions which allow one to easily manipulate a stack, and since GCC targets AVR, you don't have to deal with Microchip's crappy compiler and can use whatever fun C constructs you wish and still get decent code.

Pretty apples to oranges here when saying something as general as '8-bit PIC' there are many architectures within that family, 4 last i knew. The low end ones are not intended for coding to with C anyway (although there are some poor compilers that try). The PIC18 series isn't bad to work with in C, I used the C18 compiler at the time and its 95% ANSI C.

I believe there is gcc support for the pic24/dsPIC (16bit) and the PIC32(32bit).

All that said last I knew Microchip still leads in 8bit mcu global market share.

I don't understand the connection on why we need such an efficient chip for implementation in devices which are plugged in.

If the economic benefits were so strong for those devices being connected that should have already happened.

What am I missing?

You really don't care as much when its got mains power but not all of these devices are plugged in. You will see them a lot in simple hand held consumer electronics like garage door openers, remote controllers, wireless mouses, kitchen timers and so on. In battery powered devices saving a mA make a world of difference.

mA may matter for something like a phone but really the war in the 8bit space is over uA and nA.

Many 8bit mcus end in places where their battery is expected to have a life time measured in years. Last I looked I think MicroChip is leading the way here in terms of sleep power. Their PIC XLP series only draws ~20nA while sleeping.

There is more competition in the 16bit space with the MSP430 from TI.

You seem to be missing that it is always a good idea to save power.

I don't think of AVRs as being particularly cheap relative to their competition but I haven't tried to buy any in quantity lately so what do I know. Maybe things have changed.

Reply on news.ycombinator.com