Atmels VS PICs page

November 01 2003

(also known as the corn vs potatoes and toothpaste vs soap page)

Above are Atmel AT90S2313 and Microchip PIC16F628. For the random hobbyist who wants to get into microcontrollers these two chips represent the mid-range, mid-performing microcontrollers most likely best suited to get their projects moving along. There are major differences between them and also major similarities. Which one is better to use?

To be forensic about this subject, I must first acknowledge that I personally use PICs and would not convert to Atmels any time soon, unless required for a job.

Secondly, I would need to acknowledge that in some important aspects, Atmel microcontrollers are superior to PICs. I noted the following:

Atmels execute instructions at the clock frequency while PICs execute them at 1/4 of the clock frequency. If both microcontrollers used a 4.00 MHz crystal oscillator, the Atmel would actually run at that speed while the PIC would run at 1.00 MHz. The difference seems almost trivial until you attempt to interface to high speed devices such as video and radio circuits.

Atmels have 118 instructions, PICs have 35. Clearly, if you are writing a program in assembly you would like more instructions available for your discriminate use. I would personally like higher math functions included in assembly language but that is asking for too much.

HOWEVER - Reviewing the actual instruction differences I noted that the extra Atmel instructions did not affect my current PIC programs much, at least at this point in time. Following is a quick comparison table:

	Atmel AT90S2313			Microchip PIC16F628

Top clock speed	10 MHz			20 MHz *
MIPS at max speed	10			5
Number of instructions	118			35
Memory	128 bytes			224 bytes
EEprom size	128 bytes			128 bytes
Program space	2048 bytes			2048 bytes
I/O pins	15			16
Number of pins	20			18
External oscillator?	REQUIRED			OPTIONAL
Power consumption	0.8 mA idle, 2.8 mA active			1.0 uA idle, 2.0 mA active
Price	$3.44 $2.82 $2.52	/ / /	1 25 100	$3.05 $1.73 $1.61	/ / /	1 25 100

* Note that the "top clock speed" refers to the max. oscillator clock speed and not millions of instructions per second. Both chips have PWM modules, Comparators, Timers, Counters, Watchdog timers, in circuit programming, Full duplex UART modules so I did not bother reviewing them.

I have two different conclusions, for two different groups of people.

The first conclusion is written for people who use either of the microcontrollers and are considering switching to the other. My answer is : don't do it. The two chips are frighteningly similar and the differences don't persuade me to bother spending my time to procure resources and effort to adapt to the other. For my little projects a PIC will do for now simply because that's what I started out with and know best. Someone who has started with Atmels should stick with them. It would be senseless to waste time to convert just for minimal gain in performance or cheaper production.

The second conclusion addresses those who haven't used either of the microcontrollers and would like to get started. Both chips are very similar. Atmels are more suitable for C compilers (for those of you who are afraid of assembly). PICs give you more bang for the buck in some aspects : 16 out of 18 pins can be I/O as opposed to 15 out of 20 pins on the atmels. This particular PIC has an internal 4.0 MHz resistor-capacitor oscillator that brings the external component count down since you do not need to supply a crystal oscillator and stabilizing capacitors. The PIC has more memory but for most applications it seems to be a negligable difference. Less instructions doesn't mean "less complicated" or "less sophisticated" considering the actual instruction differences and similarities.

Neither of the microcontrollers will make your life easier when it comes to doing complex math stuff so it doesn't really matter. For higher speeds go with Atmels. For out-of-the-box projects with lowest number of components, use the PIC16F628.

Before deciding to use either the PIC or the Atmel, check out their dependencies - see how much effort it would take you to get one working, how easy, reliable and documented is the programmer device, and could you use the said programmer for a different model of the chip. I say - go with the PICS simply because I started off with them. They're simple, they're complex, they can do whatever you want them to do.

To make an analogy that's worthy of some angry comments, an Atmel to a PIC is a corn to a potato and toothpaste to soap. One makes whiskey, other makes vodka. Both get you drunk. You can't use soap to clean your teeth with and you don't want to clean anything else but your teeth with toothpaste. Go figure.. Just my five cents.

E-mail me with corrections/comments/angry one-liners.

..back to main page