Society of Robots - Robot Forum

Software => Software => Topic started by: Deruty on August 13, 2009, 01:06:43 PM

Title: Strange power issues
Post by: Deruty on August 13, 2009, 01:06:43 PM

When I turn a port off instead of going to 0v the pin continues to supply aprox. 1.9v Can anyone help me w/ this. I'm using the $50 robot tutorial btw.

EDIT: I read some other people's problems and figured it out. Thanks anyway.

Title: Re: Strange power issues
Post by: sonictj on August 13, 2009, 02:03:42 PM

if your DDR register is set your port might act like this.  Is there a problem, or are you asking out of curiosity.

Title: Re: Strange power issues
Post by: chelmi on August 13, 2009, 02:20:40 PM

Quote from: sonictj on August 13, 2009, 02:03:42 PM

if your DDR register is set your port might act like this.  Is there a problem, or are you asking out of curiosity.

hmmm it should not. Low state is 0V to 0.7V, high state is 2.2V to 5V. 1.9V is in the "gray" zone and is invalid.
Deruty, what was wrong ?

Title: Re: Strange power issues
Post by: sonictj on August 13, 2009, 02:56:36 PM

Quote

hmmm it should not. Low state is 0V to 0.7V, high state is 2.2V to 5V. 1.9V is in the "gray" zone and is invalid.

I thought there were different threshold associated with input versus output on the AVR but I could definitely be wrong about that.

**EDIT: checked and chemli is definitely right 1.9V is in the gray zone.