I'm using USB tiny with the Atmel 328p chip. Avrdude works fine. Finds the chip etc. I wrote a simple program using WinAVR in C++. The program is simple test to turn on an LED as follows. The MAKEFile was edited to use the right chip and programmer.
DDRB = 0b00000001; //select PortB pin 0, which is pin 14 on the chip, to output
PORTB = 0b00000001; // make pin 14 high;
while(1)
{
}
The program loads fine - no errors, the block at the bottom says the chip accepted the program, but pin 14 doesn't go high. I checked with voltage on that pin and it stays at zero.
I've tried the same program with PORTC instead of B with the same result.
Any idea what's going on? Why doesn't this work?
Programs Load but Specified pins don't respond
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- cs137
- Posts: 22
- Joined: Thu Feb 23, 2012 9:15 am
Programs Load but Specified pins don't respond
Last edited by adafruit_support_rick on Sat Jan 26, 2013 10:31 am, edited 1 time in total.
Reason: Moved topic to General Project Help
Reason: Moved topic to General Project Help
- zener
- Posts: 4567
- Joined: Sat Feb 21, 2009 2:38 am
Re: Programs Load but Specified pins don't respond
I am a PIC guy so I can't tell you specific answer other than read the IO section of the data sheet. There is a difference between the data register and the actual pins. There is a difference between writing to the register and setting the output. Probably just different syntax is needed.
- zener
- Posts: 4567
- Joined: Sat Feb 21, 2009 2:38 am
Re: Programs Load but Specified pins don't respond
You might also try putting a pullup resistor on the pin and see if it goes high. Maybe it is set up as an open collector.
- cs137
- Posts: 22
- Joined: Thu Feb 23, 2012 9:15 am
Re: Programs Load but Specified pins don't respond
The problem is resolved - I think you were on the right track regarding the pullup resistor.
I'm not sure why but it had something to do with the power supply. Originally, I disabled the power from the programmer and was using a separate power supply because I looked at a video where it advised using a separate supply. In any case, when I disconnected the separate supply and used power from the programmer the problem disappeared.
Thank you for your help.
I'm not sure why but it had something to do with the power supply. Originally, I disabled the power from the programmer and was using a separate power supply because I looked at a video where it advised using a separate supply. In any case, when I disconnected the separate supply and used power from the programmer the problem disappeared.
Thank you for your help.
- zener
- Posts: 4567
- Joined: Sat Feb 21, 2009 2:38 am
Re: Programs Load but Specified pins don't respond
Thanks for reporting back. So often people don't say what ever happened. I don't think my advice was too good but it's good that you got it working anyway. It seems a little strange though.
Please be positive and constructive with your questions and comments.