AVR-Chat

No AVR part is useless after programming the fuse bits.  You just have to
use the appropriate programming method - fortunately the STK500 supports
both ISP and Parallel programming.  For example, program the RESET line to
be an I/O pin on the tiny26 and you are REALLY HOSED, unless you use
parallel mode to "recover" your chip.  However, for the run of the mill: I
programmed an external clock...  You simply enable the external clock drive
on your STK500 - read the manual about those little jumpers near the back of
the board.

There are gotcha's with ISP: if your target board has an output driving the
MISO or SCK then it won't work.  I arrange my designs to have the ISP lines
brought directly out to the header and then insert 4.7k resisters between
the ISP pins and the rest of the circuit.  I just don't put any high-drive
elements on the other side of the resisters (e.g. LEDs)

Cheers!

-----Original Message-----
From: Ian Drennan [mailto:ianid@sai.co.za]
Sent: Saturday, November 06, 2004 6:03 AM
To: AVR-Chat@yahoogroups.com
Subject: Re: [AVR-Chat] Fuse gotchas (was Re: STK500 starter kit)




> I agree that this is an issue for beginners and more attention should
> be brought to it.
>
> Recall that I discovered that fuse gotchas are solved for AVRs with
> the JTAG interface because this interface does not require the clock
> to be running so you can repair any fuse misconfigurations.

Greetings all

I have been following this thread with  interest as I am new to AVR and am
about 3 weeks into using my new STK500.
The 'fuse gotcha' issue seems to have got me today when I plugged in a new
Mega8 and changed an oscillator fuse so as to run using the STK500 onboard
clock. I set the fuse for external clock i.e.. Ext. Clock; StartupTime: 6CK
+ 64 ms;[CKSEL = 0000 SUT = 10]

Obviously this was a mistake as I am now locked out and assume the part is
now useless. Please can someone advise what the fuse setting should have
been to allow the mega8 to run using the STK500 onboard clock.

Many thanks
Ian






Yahoo! Groups Links