Re: universal programmer

In article <11qoqhlquql4kd3@xxxxxxxxxxxxxxxxxx>, "Abstract Dissonance"
<Abstract.Dissonance.hotmail.com> says...

> Since I'm trying to get into MCU it seems I will need a programmer to get
> anywhere. From looking online it seems that any "decent" programmer is
> pretty expensive(1k+) and those that are cheap seem to offer very few
> features and few chip support.

This is my understanding. I invite others to offer constructive
correction if I mis-speak.

There are two distinct classes of device programmer. The dividing
line is whether they're dedicated to memory devices, such as EPROMs,
EEPROMs, FLASH devices, etc., or whether they are true 'universal'
programmers with pin-driver architecture.

Dedicated programmers are fairly simple units, designed to be
inexpensive and to perform a limited range of functions for just a few
families of chips. This is because the programming algorithms required
for EPROMs and such are not particularly complex in themselves.

The next step up is an architecture called 'pin-driven.'
Programmers based on such technology are at least an order of magnitude
more complex -- and, consequently, more expensive -- than those that are
not pin-driver capable.

Neat thing about pin drivers is that they're software-controlled.
You can program any pin in the programming socket to do anything you
need it to do: Vcc, ground, address, data, programming voltage,
programming waveform, whatever. Pin driver technology also gives you
very precise control over signal timing.

This means that you can, in theory, set them up to handle
read/program for any imaginable programmable device. Functionality like
that does not come cheaply.

> I was thinking that it shouldn't be very difficult to program just about any
> chip by using a computer if the computer had "access" to all the pins on the
> chip. From looking at a few data sheets it seems that its very easy to
> program a MCU by simply handling the procedure through the software.

It's a lot more complex than it may appear at first glance. True
"universal" programmers are, in fact, small dedicated-purpose computers
designed to do exactly as you describe.

Example: I use Data I/O's Unisite and 2900 series programmers.
They both require their own operating system, and they both contain all
the elements of a microcomputer: CPU, memory, hard drive (in the case of
the Unisites, anyway), and I/O functions.

The Unisite and 2900's are most definitely pin-driver based, and
the pin driver cards alone are complex enough to make me cringe. Each
pin driver board (the Unisites have 17, with each board capable of
driving four pins of the programming sockets) has a customized CPLD on
it in an 84-pin PLCC package, and enough logic and discrete components
that it looks like a tiny city under a magnifier.

> heres a quote of how to program the PIC16C84

<snip description>

Coordinating all those pin transitions and data flow is one very
good reason why PIC programmers are either inexpensive, and dedicated
solely to PIC chips, or universal and a lot more expensive.

> It seems to me that if most chips follow a very similar method where you use
> a few pins(lets say arbitrary too) to get it into program mode and a serial

They don't. Every single manufacturer uses different algorithms
and pin levels to program their chips. Algorithms from Intel, for
example, would be worthless (and probably even damaging) to a PIC chip,
and vice versa.

The bottom line: Good programming hardware is a tool. An
investment. Treat it as such, bite the bullet, and shell out the bucks
for a unit that meets your needs.

HOWEVER -- this does not necessarily mean you have to shell out
thousands for the latest/greatest stuff. I bought my hardware used, at a
fraction of what DIO wanted for it new.

Also, I've seen Advin 'Pilot MVP' programmers (really outstanding
units, actually) go on Ebay, brand new, for around $500 (they're
normally $900 or so), and they have free software updates for life.

Such a unit will most certainly read/program any PIC chip you may
choose to play with (though you will need an adapter if you want to do
something other than a DIP package), not to mention a whole raft of
other memory and logic devices. If I were shopping for a second
programmer, I'd go with an MVP in a heartbeat.

Happy hunting.


--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute.
(Known to some as Bruce Lane, ARS KC7GR,
kyrrin (a/t) bluefeathertech[d=o=t]calm -- www.bluefeathertech.com
"If Salvador Dali had owned a computer, would it have been equipped
with surreal ports?"
.