Re: [tlug] PIC v. ARM: elegance/awkwardness and price; evaluation kits; SMT

[jep200404 <jep200404@example.com>]

Ian Wells wrote:

> 2008/11/13 jep200404 <jep200404@example.com>:
> >> ... Microchip stuff ...
> >> ... they're $5 per reprogrammable chip, ...
> >
> > Compare that to $1.56 [1] and $1.8375 [2]
> 
> How much to set yourself up for developing with them?  PIC
> reprogrammer/prototype boards run at around $30. 

$20|$30/$5/$0 for EDTP Easy ARM

   http://www.edtp.com/download/arm/easy_arm_pkg.zip

You can still get the support files, but not the board. 
I think the full price for an EDTP Easy ARM kit was about $20 or $30. 
A friend bought one at at full price, then one or two more at 
$5 each during a close-out sale. Then he gave me one in exchange 
for soldering his. I went on to build a prototype for a real 
product with them. There are plenty of silimar boards out there. 
I think they start around $50 and go up from there. 
I used gcc, so the compiler is free. 

$49 for LM3S811 evaluation kit

   http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=726-1042-ND
   http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=726-1043-ND
   http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=726-1044-ND

and later Ian added: 

> And to reply to myself, [PIC chips] really are cheap...  

Yup. Been there, done that, and I wrote about it: 

> 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. 

with my conclusion: 

> 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. 

Back to what Ian wrote: 

> The problems would be being dealing with an LQFP package, ...

Surface mount stuff used to scare the heck out of me. 
Then I had to do some significant SMT soldering a few years 
ago and survived. Now, it's just plain fun to solder SMT parts. 

The most important tool I have for SMT work is my old Ungar 
soldering iron that uses a chisel shape tip made of bare copper. 
As the solder dissolves the copper, I file the tip so the 
corners of the chisel are _sharp_. The sharpness of the corners 
is a great help in applying very small amounts of solder. 
The chisel shape and the ability to refile the bare copper 
to maintain the sharpness of the corners and edges of the 
chisel shape are the essential qualities I need. 

The sharpest corners of the sharpest iron plated tips, 
are actually rounded; so you get too much solder between 
the SMT joint and the iron plated soldering tip. 
If you file an iron-plated tip, the copper inside will 
dissolve fast, and the iron will not dissolve at all, 
quickly leaving an empty hull. You'll have to refile an 
iron-plated tip much more than a bare copper tip. 
Unfortunately, only iron-plated tips are available for 
most of the fancy temperature-controlled rigs.