Hello, experts!
I've just started to work with AVR series microcontrollers, especially AT90S8515. My question is regarding how to make this controller work w/o STK500 card. I can't figure out which legs should be connected somewhere and which not...
I'm using only PORTB to output voltage in order to run my single LED.
Please provide me with a simple scheme, showing how to connect all the unused legs.
Thanks in advance,
Best Regards,
Dmitry.
Ok, here I go :)
Perhaps my problem description was a bit weird, but the point is:
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Imagine, that the only thing you have is a programmed AT90S8515 microscheme.
The world is void around, except tree things:
1) +5V wire (Vcc) [connected to leg 40];
2) GND wire [connected to leg 20];
3) LED, connected to the +5V wire with one leg and the other connected to the microcontroller's first (0) leg.
NOTE: A special reminder is that the program in microcontroller is using internal tick generator in order to turn the LED (leg "0") on and off (switching it's state once a second).
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Now, there's the problem: I need every single microcontroller's UNUSED leg connected to something (?except ports?)... So, can you provide me with some assumption, please?
Regards,
Dmitry.
Thanks for such exhausting answer :)
So the last question is regarding quartz generator:
as far as I got it, i can't run internal timers unless i have external crystal?
Regards,
Dmitry.
One mor thing you should do with your setup that will save you some headaches and probably some parts. You should not connect the LED directly to the +5v source but instead go through a small resistor to the voltage source. This will limit the current going through the LED which will prevent it from getting fried (LED's can burn out if you abuse them) and while the 8515 has a bit more tolerance it's input pin could also be damaged. A resistor value of 270 will keep the current down to about 12 mA which will keep both the LED and the 8515 happy.
Nick
yup, i know about the Leds :) actually, the led I'm using for test purposes has huge internal resistance, thus it works perfect :) the voltage falls to 3.5volts after him if measured :)
TO Sonnya: ahh, i see then :)
(Newbie here, so apologies if I am wrong.)
If you don't use a reset controller, and instead use a cap and resistor on the reset pin, the data sheet says that the minimum value for the resistor is 100K ohms.
This resistor came up for discussion on this board about a month ago, because someone was trying to determine if the 100K resistor was a diagram of the internal resistor, or if it was an external resistor requirement.
The consensus was that it was an external requirement, and that the minimum value for external resistor was 100K on the reset line.
Daniel
