Re: [avr-chat] Crystals (was ATmega32 @ 16MHz : fuse bits ??)

[Vincent Trouilliez]

Sorry for the late reply...

Thank you so very much everybody for all the detailed information for
both my crystal problem and JTAG questions.

JTAG:
-----
After 2 months working on my first AVR project, I quite love these chips
and will probably stick with them for a few years, so I am thinking long
term regarding development tools. That means JTAG ICE MkII it seems.
I found this page on Atmel's site:
http://www.atmel.com/dyn/products/tools_card.asp?tool_id=3353

so I can at last see what's really about.

Q1: how much does it cost ? 
Q2: since there are Mk1 clones, are there mk2 clones ? Or at least one
in the pipeline ?



Crystals:
---------
Graham wrote: "I don't recall you mentioning the hardware arrangement
you are working with, but now that you are writing about "hand made/DIY"
cables it is, perhaps, an economy set-up.Oh, and what is the exact
manufacturer's part number on your MCU?"

I use a large strip prototyping board, and add components to it over
time as required/needed by the development of the software.
I soldered the crystal and capacitors as closely as possible to the AVR
chip, 4 tenths of inches from it maximum then. However due to the XTAL
pins being next to each other, and the crystal having its terminals 2
tenth of inches apart, one of the crystal terminals is obviously a lot
closer to the AVR than the other, so maybe the capacitance is unbalanced
between the input and output of the oscillator, and this keeps the
oscillator from starting ?? Hmmm.... I will try what you did.... remove
the capacitors altogether, and connect the crystal alone, with a few
inches of wiring. I have nothing to lose.
In the meantime, I pushed the internal RC oscillator to its limit...
8MHz. I timed all the sensitive parts of my program and this frequency
seems to be fast enough. However it's not accurate (I measured it at
roughly 8.5MHz !!) so although the UART appears to work fine, it's
foolish to count on it I think, as it may well start throwing out
garbage depending on the ambiant temperature...

As for the part number, I made sure I ordered an Atmega32-16PI, not 8PI,
precisely to get it running at 16MHz, hence my disappointment that it
fails to run at that speed...


Regards,


--
Vince