• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 80 subscribers
  • Views 819 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Ground issue MSP430

david hormaza
Prodigy 50 points

Hi all, I'm pretty new in this and I would like an explanation and maybe a solution for my problem. I'm doing a program with the MSP 430 that is taking care of two different sources and depending on the amount of these sorces the outputs from the MSP draws 0 V. If there is no sources it should draw 5 V.

The issue is that I have another circuit that interacts with the MSP which is receiving the external sources. When this circuit is off (the sources doesn't have the enough current to power on all the system but the power is more than innexistent which means that the MSP output should be zero) the MSP works and their output is what I desire, 0V. However when the sources has the minimum current to turn on the system, the outputs from the MSP draws 1.7 V instead of 0V. If you take of the MSP pin from the circuit, you have the 0V, but whenever you connect it to the circuit (and the system is powered on) it draws 1.7 V. This is a real problem for my circuit. How can I fix this. 

Please anybody help me. 

Thanks

  • 0
    Guru 12050 points

     >taking care of two different sources and depending on the amount of these sorces the outputs
     >MSP draws 1.7 V

    None of these words are used in electronics.

    What is: taking care of source?

    it draws 1.7 V? current is draw, voltage is a state.

    Are you using a online translator that is making no sense, or do you need to read basic electronic book.

  • 0
    Guru 23000 points

    If the MSP430 is not powered to Vcc but one or more of his other pins are directly connected to another powered system, the MSP430 will be powered also via his internal protection diodes on his other pins.

    Use resistors or diodes between both systems.

  • 0
    Guru 46710 points

    david hormaza said:
    MSP 430 that is taking care of two different sources and depending on the amount of these sorces the outputs from the MSP draws 0 V. If there is no sources it should draw 5 V.

    It is hard to understand what you mean. Are you saying that you are powering msp430 from 5V supply and mp430 pins shall have either 0V and 5V output levels? - Msp430 power shall not exceed 3.6V

    david hormaza said:
    However when the sources has the minimum current to turn on the system, the outputs from the MSP draws 1.7 V instead of 0V.

    You want to say that msp430 does not pull it's pin strong enough? Mps430 outputs are not so strong, refer to graph from datasheet below. If you want stronger "pull" - use N-FET transistor as switch

**Attention** This is a public forum