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Re: [avr-libc-dev] Newbie: Help walking through the demos

From: Joerg Wunsch
Subject: Re: [avr-libc-dev] Newbie: Help walking through the demos
Date: Fri, 30 Dec 2005 21:45:25 +0100
User-agent: Mutt/

As Mark J Elkins wrote:

> I'm trying my best to follow the Demo Projects from
> http://www.sax.de/~joerg/avr-libc-user-manual/group__demo__project.html

Well, that's only a documentation preview, mainly intented for
developers.  It's even stale now, instead, use the official
documentation at:


> So: Downloaded avr-libc 1.4.1 and found the include file...
> (perhaps the folk creating the Emerge-able stuff didn't consider deo's
> needed - and the web-site demo link to this file is broken)

Well, avr-libc 1.4.1 isn't even 24 hours old by the time of this
writing. ;-)  I'm impressed the package maintainers already followed
up with updated packages that quickly.  Congratulations!

> however, define-ing "ATMEGA8515" gives me a ..
> "Don't know what kind of MCU you are compiling for"

Well, the simple demo is supposed to work on about any AVR on earth,
but so far, it seems nobody ported it to the ATmega8515.  Patches are
welcome, my guess is it would work straight away using the same code
path as an AT90S8515 (perhaps you could even lie about your CPU, and
just claim you were compiling for an AT90S8515).

It's also news to me the STK500 now ships with an ATmega8515.  The
last kits I've seen still had an AT90S8515 one.

> I could use the atmega16 - as iocompat.h knows about that chip...  -
> the code appears to compile fine... (Not completely sure what the
> difference/advantages are between the two supplied CPUs yet)

For the purpose of the simple demo, only minimal resources are needed,
so both should be fine (modulo the problems explained above).  For the
more advanced demos, they are only ported to an ATmega16 (as I know it
comes along with the STK500), and the "largedemo" will need a
controller with an ADC anyway, so the ATmega8515 would not be

> I'd like to start experimenting without damaging anything (just yet
> :) (ie - I'm not too confident in removing the in-place mega8515 -
> and inserting the mega16 - which I think needs to be placed in the
> other 40 pin connector) - so if any one could give me some guidance
> ..

Yes, the ATmega16 is an "analog" device, i.e. it's got an ADC.  All
AVRs that have an ADC use a completely different pinout where the
supply pins are not at the corners of the device but in the center (so
they can much better be bypassed with capacitors).  If you look at the
1.4.1 documentation, it contains pictures (in both, the largedemo and
stdiodemo setups) where you can see where to place the ATmega16 into.
These photos also show where the JTAG ICE would be connected to (can
be seen to the left of the photo), and where to place the ISP cable to
(right in the back of the photo; it is the same header as for the

> I'm also looking for someone to handhold me through uploading the
> Hex code to the STK500 (using avrdude??)... ie what Jumpers and
> Cables (ISP6PIN to SPROG3?, and Serial into RS232Ctrl?) I should be
> using on the board - and what parameters should be used with avrdude
> - if used.

Sorry to refuse, but this list is the list for avr-libc developers.
For very basic questions, please use address@hidden, which is
a list of AVR users.  There will be many more people than just the
library developers who could help you out on this.

> I should then be able to work through the other exercises
> myself... (but pointers are welcome - I got myself a separate
> HD44780 LCD)

Please read through all the documentation of the demos.  It's been
much more work to write that up than to craft the few lines of demo
source code, so I hope the best it will be useful to people.  Of
course, if you've got suggestions on what to change, you're welcome to
send them to this list here, or to fill in a bug (or patch) tracker
item on the web site.

cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)

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