[chbot] Atmel Programmers

[Volker Kuhlmann]

On Wed 19 Oct 2011 11:36:58 NZDT +1300, Jasper Mackenzie wrote:

>   At the last meeting I was talking to a few of you about programmers as I  
> need to move away from the wonderful butterfly to more wonderful things  
> like attiny's...

I posted on programmers semi-recently. Basically I don't see a market
for them. AVRs are programmed over their ISP interface, which looks to
me like it's conceptually pretty close to SPI. You can use any Arduino
for this, burn the boot loader sketch from the IDE menu onto the
Arduino, hook up your target CPU and you've got your STK500 compatible
programmer. If you use the Arduino boot loader afterwards, you only need
to do this once. I wouldn't make a PCB for that. Small Arduinos are
cheap, so it depends on how many hours you want to spend to save $20.

> Synco said he was using a usbprog which does seem like a very complete  
> programmer. My questions with this programmer are:
>   a) can it do 1-wire debug - I couldn't find anything on the the usbprog  
> website to suggest so. If not, is there a DIY programmer that does?

No and no. Atmel's debugWIRE is proprietary, specs are not available,
not even under NDA. It works by bit-banging the reset line. It's only
used for debugging, not for programming. The ...CN JTAG adapter from a
Chinese manufacturer James mentioned supposedly does debugWIRE. They
don't answer emails though and there's no good supplier. The other cheap
box that does it is Atmel's Dragon. What they don't tell you is that it
will only work with avrstudio (or whatever it's called) under 'doze.
That's because those JTAG etc adapters contain no software, only pin
drivers, voltage level converters and some such, so all the control
happens from some software that knows the details of debugWIRE. Needless
to say, there's no Linux version available.

JTAG adapters are also used for programming, but to buy one just for
that would be silly. You're out of luck again on the small AVRs - only
the ones in the Arduino Megas have JTAG interfaces, on the smaller ones
there aren't enough pins to go round and there's debugWIRE only. It
won't program your chips anyway.

>   b) How in the heck as a total C n00b do I use the jtag etc. meaningfully?

The usually successful n00b approach with anything is one step at a
time... :-)
C and JTAG are two different things. If you don't learn to program in C
you will not become happy with microcontrollers (unless maybe you
restrict yourself to the really big ones - tip: the attinys are not
it...). I find C++ an improvement over C. A few things are different,
and a few don't apply to microcontrollers - like exceptions and
templates (which you can't/don't want to use).

If you're that new to microcontrollers you seriously should start with
one of the Arduinos and its bootloader. Plug it into your USB and be
done. The whole Arduino environment is superb for quick starts, though
the IDE in the long run isn't quite professional enough. No debugging
though, other than by what's known as the printf() method, but that does
go a long way.

You don't buy a JTAG adapter just for programming, it's a waste. If you
do get one, don't get any from anyone who also sells software, they're
almost always proprietary rubbish. Good suppliers are Amontec and
Olimex. Make sure you get a hispeed one (480MBit/s), from what I've
gathered so far the 12Mbit/s ones drag you down too much. The only
open-hardware adapter I've seen is the Flyswatter, unfortunately it's a
slow one. It'll work, but probably not comfortably enough. You need
openOCD for that, which I'm about to try. I'm still getting the eclipse
AVR plugin to work, it's pretty buggy (the plugin, not eclipse). My goal
is to have this working for ARMs and possibly PIC32 too.

Volker

-- 
Volker Kuhlmann
http://volker.dnsalias.net/	Please do not CC list postings to me.