You mentioned before that you intend to blink an LED with this, right?
You can connect the LED portion of your circuit as either of the
following, and the resistor can go on either side of the LED. (The long
leg of your LED should be toward power, or away from ground.)
AVR output pin -> LED -> resistor -> ground
AVR output pin -> LED -> resistor -> power (VCC)
You can expect the LED to drop about 1.7V, so if you are supplying 5V, you
have 3.3V to be dropped by the resistor. Ohm's law (which applies to
resistors, but not everything) tells us that V = I * R. You want a current
of about 20mA to light the LED. Thus, use a resistor with
R = 3.3/.02 = 165 Ohms. These numbers are rough enough that you should
be fine with any similar resistor you happen to have.
Forgive me if this is more detail than you wanted.
-Marge
On Sun, 23 Mar 2008, Robert L Cochran wrote:
Joerg Wunsch wrote:
Since it's small enough to post, here's the hex file when compiling
for an ATmega644:
:100000000C9438000C9455000C9455000C94550039
:100010000C9455000C9455000C9455000C9455000C
:100020000C9455000C9455000C9455000C945500FC
:100030000C9455000C9455000C9455000C945700EA
:100040000C9455000C9455000C9455000C945500DC
:100050000C9455000C9455000C9455000C945500CC
:100060000C9455000C9455000C9455000C945500BC
:1000700011241FBECFEFD0E1DEBFCDBF11E0A0E065
:10008000B1E0ECE6F1E002C005900D92A030B107BE
:10009000D9F711E0A0E0B1E001C01D92A330B10793
:1000A000E1F70E94AB000C94B5000C9400001F9285
:1000B0000F920FB60F9211242F933F938F9380913D
:1000C0000001882379F420910101309102012F5F12
:1000D0003F4F309302012093010183E02F3F380707
:1000E000D9F417C0813029F020910101309102012B
:1000F00013C0209101013091020121503040309312
:100100000201209301012115310531F41092000103
:1001100003C081E080930001309389002093880020
:100120008F913F912F910F900FBE0F901F901895B8
:1001300083E880938000E1E8F0E080818160808343
:10014000109289001092880080E28AB981E0809341
:100150006F00789408950E94980083B7816083BFF0
:0C016000889583B78E7F83BFF8CFFFCF58
:00000001FF
Thanks Joerg for posting this. I have a breadboard circuit ready to test
with this hex file. I was planning to use a lithium polymer battery that
pumps out 12v at 1300 mA. I connected that to a power supply board which
will give me 5v output and 1100 mA current. That is way too much current
for the Atmega644, isn't it? The absolute maximum ratings on the
datasheet list 200 mA as the maximum on VCC and GND. Of the "wall wart"
power supplies I am using, I have one that puts out 5v and I've measured
350 mA current. So I need to cut down the current for the AtMega 644
device, right? I can reduce the current with resistors? I will Google to
learn how to do this.
Thanks
Bob Cochran
_______________________________________________
AVR-chat mailing list
AVR-chat@nongnu.org
http://lists.nongnu.org/mailman/listinfo/avr-chat
_______________________________________________
AVR-chat mailing list
AVR-chat@nongnu.org
http://lists.nongnu.org/mailman/listinfo/avr-chat
