atmega168 strange result.
Posted: Sun Apr 12, 2009 3:35 am
I have been trying to get my avrusb software to work on my 168 for sometime now and I think I just noticed the problem but I'm lost to why?
for reference
my d- is portD pin 0
my d+ is portD pin 2
I was checking the voltage of my d- line to see if I get a different voltage with my atmega8 when I noticed my d+ is stedy at 4.7 volts. Personally I though this was a bit stage, so I check the atmega8. the 8 chip was not showing this voltage. So for a sanity check I tested the 168 again and its 4.7 volts. I can power an LED with it just fine... but why? My project run at about 4.7 so my guess is that I'm routing this voltage with an internal pull up or pin configuration somehow? I know the source code runs fine on an atmeg8, I made only the changes needed to go to the atmega168, so what could it be?
I read something about the int0 needing to by set on the pd2 pin, could this be the issue?
My post is here for reference viewtopic.php?f=8&t=2360
Further investigation shows this voltage is coming from the use port. It also is not always there and as far as I know could be normal behavior . If I monitor the voltage with the mega8 chip its very different and more like pulses of data. Perhaps was I'm seeing is the usb device attempting to communicate.
for reference
my d- is portD pin 0
my d+ is portD pin 2
I was checking the voltage of my d- line to see if I get a different voltage with my atmega8 when I noticed my d+ is stedy at 4.7 volts. Personally I though this was a bit stage, so I check the atmega8. the 8 chip was not showing this voltage. So for a sanity check I tested the 168 again and its 4.7 volts. I can power an LED with it just fine... but why? My project run at about 4.7 so my guess is that I'm routing this voltage with an internal pull up or pin configuration somehow? I know the source code runs fine on an atmeg8, I made only the changes needed to go to the atmega168, so what could it be?
I read something about the int0 needing to by set on the pd2 pin, could this be the issue?
My post is here for reference viewtopic.php?f=8&t=2360
Further investigation shows this voltage is coming from the use port. It also is not always there and as far as I know could be normal behavior . If I monitor the voltage with the mega8 chip its very different and more like pulses of data. Perhaps was I'm seeing is the usb device attempting to communicate.