• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 3 answers
  • Subscribers 54 subscribers
  • Views 1618 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.

RTOS/CC1310: why can't enable weak pull up on uart rx pin?

shaowei
Intellectual 780 points
Part Number: CC1310

Tool/software: TI-RTOS

Hi, 

during the test, we found the CC1310 UART RX pin can't be pull up by internal weak pull up setting. it can only be pull up by an externally connected pull up resistor?

is this true?

I already modify the setting to:

 CC1310_LAUNCHXL_UART_RX | PIN_INPUT_EN | PIN_PULLUP, 

and use 

IOCPinTypeUart(UART0_BASE, CC1310_LAUNCHXL_UART_RX, CC1310_LAUNCHXL_UART_TX, IOID_UNUSED, IOID_UNUSED);

is there any other code to be added to enable the internal weak pull up setting on uart Rx pin?

if without pull up, when board be powered up, and the uart port connection being left open, cc1310 uart will rx garbled codes.

B/R,

Shaowei

  • 0
    TI__Guru* 86131 points
    Which HW are you running on ? On our Launchpads there is an external pulldown on the UART_RX line. The UART_RX signal is also configured with internal Pulldown. When opening the UART driver, the pin is reconfigured to have no pull, assuming that when you are using the UART the pin is connected to something that is driving it HIGH or LOW the way it is supposed to.

    BR

    Siri
  • 0 in reply to Siri
    Intellectual 780 points

    Hi, Siri,

    Thank you for the reply.

    we do it on our own board.

    we left uart rx pin open (no external pull up or pull down resistor), we expect it to be pull up by the weak internal pull up setting.

    As I mentioned  in my last post, I already modify the setting to:

     CC1310_LAUNCHXL_UART_RX | PIN_INPUT_EN | PIN_PULLUP, 

    and use 

    IOCPinTypeUart(UART0_BASE, CC1310_LAUNCHXL_UART_RX, CC1310_LAUNCHXL_UART_TX, IOID_UNUSED, IOID_UNUSED);

    but it seems that it didn't work. when the board uart port left open and just apply power to the board. CC1310 uart rx pin will randomly go low, thus can cause noise data being received by the uart.

    we expect it should be pull up by the weak internal pull up setting.

    B/R,

    Shaowei

  • 0 in reply to shaowei
    TI__Guru* 86131 points
    If you are using the uart driver the UART_RX pin will be reconfigured to PIN_NOPULL when doing a uart_Open.

    Please see the following post on how this can be modified:

    e2e.ti.com/.../2505526

    BR
    Siri
  • 0 in reply to Siri
    Intellectual 780 points

    Hi, Siri,

    thank you!

    I followed that instruction in the post e2e.ti.com/.../2505526 which you mentioned, but seems it didn't help.

    anyway, by tring more test, when adding the below code after UART_open() will solve this issue:

    IOCIOPortPullSet(CC1310_LAUNCHXL_UART_RX, IOC_IOPULL_UP);

    B/R,

    Shaowei

  • 0 in reply to shaowei
    TI__Guru* 86131 points
    Glad you were able to get it to work. Remember that when you modify the driver you need to include the file manually into your project.

    BR
    Siri