[time-nuts] I want a good micro-controller

[Chuck Harris]

wje wrote:
> As the one who made the first comment about not liking the PIC, I'll 
> give you my reasons. Yes, they are philosophical, even religious. I'm 
> also distinguishing between microprocessors (this discussion) and other 
> variants, such as DSPs, FPLDs, etc.
> 
> First, I've used a very large number of different micros over the years 
> for both 'real' work and my own purposes, starting with the Intel 8008 
> before it was commercially released. I've used Intel, TI, Motorola, 
> Zilog, MOS Tech processors of multiple families, and yes, even PICs, all 
> with wildly varying architectures. These days, given modern development 
> tools, the architecture of a general-purpose micro really isn't 
> particularly relevant. It's functionality and support tools that are 
> important.

I too have a list of micro's and mini's as rich as yours:  PDP8, Univac
11XX, IBM360, PDP-11, 680XX, 8008, 8080, 8085, 8088, 8086, 80186, 80286,
80386, ... DSP-32, 1802, Z80, 8051, 6502,..., and many, many PIC's.  And
with the exception of the first 5, I have been paid to program them all.

> Without a doubt, PIC made it possible for many hobbyists to put together 
> nice projects that they would not necessarily have been able to do 
> otherwise. My deep-seated revulsion comes from one source, and it's not 
> the architecture, the company, or the capabilities of the chips. It's 
> Basic, the language. Until relatively recently, PIC and Basic were 
> almost synonymous, at least for the masses.

Ah, well, that explains it!  Your knowledge of PIC's is incomplete.  The
BASIC PIC, known as the STAMP, was a simple program running on a PIC that
showed off somethings that you could do with a PIC.  It was not even a
Microchip product.  Parallax took a compiler they wrote, and programmed
it on an early PIC, sold millions of them as the STAMP.

For more information: http://www.parallax.com/tabid/295/Default.aspx

I have never programmed a PIC in anything other than assembler, or C.

The PIC architecture is a RISC machine.  Its memory is split into DATA
and CODE sections.  The entire data section is treated as pages of registers.
All of the I/O is treated as data locations in memory.  It is dirt simple,
having less than 40 instructions.

It is easy to program a PIC in assembler, and using a cross-compiler, it is
reasonably easy for a compiler to generate good PIC code.  I have found
that CCS's C compiler generates PIC code that is as good, or better than
a talented human programmer can write.

> I have both EE and CS degrees, and I work in both worlds. 

For me it is a BSEE and an MSEE.  I design hardware and software for
embedded systems.  My MS was about 50/50 microwaves and computer architecture.

In my humble
> (but completely accurate and stable) opinion, Basic is not a programming 
> language. It's a tool of Satan designed to convince people that they are 
> programmers when they really should stick to their janitorial duties. 
> This is a subset of the general problem that everyone thinks they are 
> programmers, and usually think their code is perfect. But, that's a rant 
> for a different audience.

Well, if you feel that way about BASIC, then you must really hate assembler.
You can write good, or bad code in any language.  BASIC is no exception.
If you treat BASIC as what it was intended to be, it is just fine.  It
is a step above a pocket calculator, and should be used as such.  In my
opinion, no BASIC program should be written that is longer than 100 lines.

> So, for me, given that there are some very good C development tools for 
> mainstream processors, and frequently they are free, I just don't use 
> PICs. As I mentioned earlier, I currently like the Motorola (I mean, 
> Freescale; these silly name changes are yet another rant) MC68HCxx line; 
> there's a wide choice of features and they can be flashed easily without 
> a complicated programmer. The 8-pin xx908QT4 is a buck and does a fine 
> job for many purposes, and most importantly, you can get a nice C 
> development environment for the line, which was originally from 
> CodeWarrior, for free. It also supports the entire line, from 8-bit to 
> 32-bit, and with builtin support for all of the various on-chip 
> 'peripherals'.

That's cool, but do any of them make a 6 pin uC that has some 10 bit ADC's
built in?  Oh, and can get to better than 1% timing accuracy over the full
industrial temperature range without a crystal?  Oh, is it available for
under a buck in small quantities?  No?  Darn!

> Even now, I don't think Microchip provides a compiler that supports the 
> low-end chips, but I haven't checked lately.

Not a valid complaint.  CCS supports everything that Microchip makes, and
their compiler costs around $100.. and it produces tight efficient code.
Plus, their library has native functions to access every feature of
the PIC.  And as an added bonus, the windows version runs nicely under
wine, and there is a linux version available too!

> But, when you get right down to it, you really need to pick the proper 
> solution for your problem. If there was something the PICs provided that 
> I couldn't get elsewhere, I'd use them. Religion is fine, but getting 
> the job done is more important.

As I said, show me a 6 pin mini SOIC that has a built in oscillator
that is accurate to better than 1% over the industrial temperature
range (and voltage), has a handful of 10 bit ADC's built in, and can
have a software UART on every pin (but one), and can be easily programmed
in C, and costs under a buck (for full industrial temperature range).
>

> BTW, for those that think you can't do anything with an 8-pin 8-bit 
> micro, I did one design that supports an LCD, a rotary encoder, a 
> Hall-effect sensor, and a button. At home, I use the same chip in every 
> light switch in my house to implement a self-tuning capacitance sense 
> switch. I even use a couple for a more time-nuts related tasks. One 
> provides loop control for my GPS/Rb/Quartz standard, and one is used as 
> a 555 timer replacement in my SmartClock->PC interface. (Ok, I was in a 
> hurry, needed a pulse stretcher, and I didn't have any 555's lying around)

I don't use 555's anymore, PICS are available that do the job better, and faster,
and with lower power consumption.  And they are more stable frequency wise.

-Chuck Harris