Re: [tlug] PIC v. ARM: elegance/awkwardness and price

[jep200404 <jep200404@example.com>]

Ian Wells wrote:

> 2008/11/12 jep200404 <jep200404@example.com>:

> > Stay away from Microchip MCUs; they have the worst,
> > most awkward architecture of any MCU I've ever seen.
> 
> I've not found Microchip stuff too difficult to understand. 

Me too. I had no trouble _understanding_ them. 

As I used them, I immediately understood and appreciated 
the 陰陽 of their nature. 

1. That they took many many short cuts which saved transistors 
   which makes the chips small, cheap, and low power, which makes 
   them very competitive. They are great money makers, both for 
   Microchip and their customers. 

2. The architecture is very awkward. This increases development 
   time and also causes inefficient code size. I used C compilers 
   for the later PIC chips, but even then the architecture made 
   C an awkward fit. 

If you're producing a high-volume product, the cheapness of 
PICs can make it worthwhile to put up with their awkwardness. 
If you're doing something for fun or some low-volume application, 
stay away from PICs. 

> ARM architectures are a good RISC implementation, with mature C
> compilers and decent address space.  You'll certainly find it easier
> to program them.  But they really didn't ought to be in the same price
> league, being a modern, fast, 32-bit chip. 

The ARM architectures were done well, so that they are 
comparatively much more elegant than the PIC chips, and yet 
take surprisingly few transistors, so although they are 
more expensive than lesser MCUs, the prices of ARM MCUs are
reasonable. 

> ... Microchip stuff ...
> ... they're $5 per reprogrammable chip, ...

Compare that to $1.56 [1] and $1.8375 [2] 

for some low-end ARM MCUs in quantity from Digikey. 
Both are reprogrammable. 
You should be able to get them cheaper elsewhere. 

I'm using much more powerful ARM MCUs and paying more for 
them than for 8-bit MCUs, but still, the ARM MCU prices are 
reasonable. They also are thrifty with power. 

[1] Luminary Micro LM3S101-IRN20 
    http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=726-1000-ND

[2] NXP (nee Philips) LPC2101FBD48-S
    http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=568-2092-ND