Re: [avr-gcc-list] newbie trying to get at90s8515 to work on breadboard

[Richard Urwin]

On Saturday 08 Jan 2005 7:01 am, Chris Donovan wrote:
> Hello,
>
>  I am trying to get an at90s8515 to work on a breadboard.  Basically
> I have an atstk500 and the chip(at90s8515) works just fine on that
> board but when I move it to a breadboard I can't get it to work
> correctly. The C code for it is below.  portb0-7 are being used to
> activate/de-activate the LED's on the stk500 board, and they work
> just fine when the chip is inserted into the stk500.
>
>  I have connected pin 40(vcc) to the +9V supply(tried 5-9V) with misc
> resistance to lower it to 5V.  When I connect up portb0 on the
> breadboard to the +LED terminal, it does not work as expected.  It
> just keeps the LED on all the time instead of blinking like it
> should. If I connect pin20 to the  the 9V it doesn't activate the LED
> at all, and the LED just stays off.
>
>  I tried getting my multimeter out and duplicating the voltages on
> the breadboard but it just doesn't work and I am not really
> electrically inclined yet(I have to look up ohm's law still), so I
> may have stuffed things up perhaps.

It would be worth checking that the LED still lights when you connect it 
to portb0. Feeding voltage directly to an LED will kill it in 
milliseconds. It's also worth putting the 8515 back into the STK500 and 
checking that it still works too.

>  I really haven't the slightest clue of why it isn't working but I am
> thinking perhaps I need to connect more pins on the breadboard to
> more things?

Could you tell us the full connections you are making to the processor? 
You don't mention 0V or RESET. These are required, as is XTAL1 and 
XTAL2 if you haven't set the fuses to use an internal clock.

If the same chip works in the STK500, and the clock speeds are 
comparable, then the software is working well enough at the moment, and 
you don't want to change it.

-- 
Richard Urwin