11 Replies Latest reply on Jan 19, 2017 1:52 AM by user_1377889

    Adding schematics components completely alters functionality

    michael_1534646

      Hi.

         

      I had similar problems a number of times already with different projects.

         

      Right now my problem is:

         

      I have a design for a BLDC motor controller, which works without problems. Now I'm trying to add UART component. Actually, I'm not even adding it, I'm re-enabling it, because I've already used it before in this design.

         

      There is no physical connection between this UART and any other component in the design (it's only connected to TX pin, RX pin, and an ISR), but after I add it, something happens and the design becomes unusable. Either state machine of the motor controller is altered, or the PWMs are somehow changed, but it just doesn't work anymore.

         

      What does "help" is disconnecting the TX pin from the component, but then I can't use the UART... Tried to use a different pin for TX - didn't help.

         

      The stupid thing is that I've already used this UART before in the design. Same UART, same pins. Just disabled it at some point and now try to use it again.

         

      As I've already said, it's not the first time I have a similar problem with various designs. But in this design I don't know how to work this around, because the UART is stand alone and is not connected to anything else.

         

      Please help!