• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 30 subscribers
  • Views 963 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.

TMS570LS1224: How to connect the unused pin

Jeff Chen71
Expert 1345 points
Part Number: TMS570LS1224

Hi,

     1. ADCIN / ADCREFHI / ADCREFLO / OSCIN / OSCOUT these pin are no internal pull-up/pull-down circut if not used should I need to pull down these pin?

Dose there have some hardware guidelines to explain that.

    2. If the pin have internal  pull up /pull down circut for example GPIO/I2C , can I unconnection these pin when I'm not used? Whether the 20uA pull up strong enough for noise interference.

    3. Reference below table. Why the ECAP1 pull type only have pull up option but the reset pull state can be pull down? 

Thanks

  • 0
    TI__Guru**** 196506 points
    Hello Jeff,

    For most of the digital pins, they have internal pull up/down, you can leave them open. Unused ADC pins can be left unconnected too. Test pin should connect to ground.

    If an external oscillator source is used, the clock source should be connected to the OSCIN pin. The OSCOUT can be left unconnected.

    ECAP1 has internal pull-up only.
  • 0
    TI__Mastermind 49120 points

    Hi,

         1. ADCIN / ADCREFHI / ADCREFLO / OSCIN / OSCOUT these pin are no internal pull-up/pull-down circut if not used should I need to pull down these pin?

    Dose there have some hardware guidelines to explain that.

    • ADCIN pins can be left open if not used.
    • ADCREFHI and ADCREFLO need to be connected to VCCAD and GND even if ADC is not used. These are reference voltages for the ADC.
    • OSCIN cannot be left unconnected. The device uses this clock as the primary source upon power-up.
    • If you have an external 3.3V amplitude square wave generator, this signal can be connected to the OSCIN pin and then the OSCOUT pin can be left unconnected. These connection options are shown in the datasheet.

        2. If the pin have internal  pull up /pull down circut for example GPIO/I2C , can I unconnection these pin when I'm not used? Whether the 20uA pull up strong enough for noise interference.

    >> Yes, unused I/O pins can be left unconnected. If they are unconnected GPIO / I2C pins, noise interference should not cause any code execution issues. These pins are inputs by default (pulled down/up).

        3. Reference below table. Why the ECAP1 pull type only have pull up option but the reset pull state can be pull down? 

    >> The table shows that the terminal N1 has the signals N2HET1[15] / MIBSPI1NCS[4] / ECAP1 assigned to it. These are multiplexing options, so that you can choose to have any one of these signals output from this terminal when configured as an output, or input to all modules when this terminal is configured as an input. After reset, this terminal "belongs" to the N2HET1 module, which asserts a pull down on this terminal. When you configure this terminal to be an ECAP1 function using the IOMM module registers, the input pull on this terminal will change to a pull-up.