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MCU-PLUS-SDK-AM263X: Configure External Input Clock for UART.

Jesus Palomo
Prodigy 25 points
Part Number: MCU-PLUS-SDK-AM263X
Other Parts Discussed in Thread: SYSCONFIG

Tool/software:

Hi TI Team,

Using the tool Sysconfig the options available for the UART clock source are: 

  1. SOC_RcmPeripheralClockSource_DPLL_PER_HSDIV0_CLKOUT0 @ (160MHz)
  2. SOC_RcmPeripheralClockSource_DPLL_PER_HSDIV0_CLKOUT1 @ (48MHz, 96MHz, 192MHz)

I want to know more about these questions:

1. Is possible to use an external input clock for the UART? 

2. Is there a pin that works as input clock for UART?

The connection that I want to know if is possible or not is to generate a clock source, let says 64 MHz, and then use the clock source as an input clock for the UART.

Any technical input will be appreciated.

Thanks.

Palomo.

  • 0
    TI__Genius 16452 points

    Hi Palomo,

    The TRM does state the UART to support an external reference clock. Let me check internally if the syscfg unavailability is a limitation or a bug.

    Regards,

    Shaunak

  • 0 in reply to Shaunak Deshpande
    Prodigy 25 points

    What is the TRM? could you share with me a technical document as reference of your comment?

    Thanks for your replay. 

    Best,

    Palomo.

  • 0 in reply to Jesus Palomo
    TI__Genius 16452 points

    Hi Palomo,

    The TRM is the Technical Reference Manual: www.ti.com/.../spruj17f.pdf

    In this, you can find the UART chapter in section 13.1.4. The TRM mentions the support for External reference clock, but the software configuration tool (SysCfg) for some reason gives only 2 clock options as you mentioned. Now, that can either be a hardware or a software issue, So I am confirming with other experts and will get back with an answer. 

    Figure 13-75 of the TRM shows extref_clk being supported. Let me confirm with our software team for the support in syscfg.

    Regards,

    Shaunak

  • 0 in reply to Shaunak Deshpande
    TI__Genius 16452 points

    Hi Palomo,

    This is a valid software bug. I have filed a JIRA ticket for the same. I expect the official fix version to be 10.00 SDK. But I will provide a small patch to fix this once I have a working solution.

    Regards,

    Shaunak

  • 0 in reply to Shaunak Deshpande
    TI__Genius 16452 points

    Hi Palomo,

    Apologies for delayed response,  I will share some more details about this. Kindly refer the TRM chapter 6.4.1.1 to see how external clock sources can be used. 

    The device has a PLL_PER Clock, (as seen in the syscfg). This takes a reference clock as an input, which can either be XTAL_CLK or EXT_REFCLK.

    For using XTAL_CLK you need to provide the reference clock on XTAL_XI pad, For using EXT_REFCLK you need to provide the reference clock on EXT_REFCLK0 pad. These are then used to give out the required frequency.

    You can read more about it in the TRM Chapter 6.4.

    Regards,
    Shaunak