• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 79 subscribers
  • Views 430 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.

MSP432P401M: DCO Init with External Resitor

Matthias Ninnemann
Prodigy 30 points

Part Number: MSP432P401M

Hello,


we're just before getting our first samples with MSP432P401M using the internal DCO. This is a Bluetooth application providing SPP with the CC2654MODA module. On the current launchpad it is used without external resisitor, but for stability reasons we plan to use an external resistor on the target. The implementation runs with 48MHz.

Two questions regarding initializing DCO with external resistor:

  1. The reference sheet (slau356; 5.2.8.1) mentions that the DCORSEL have to be 1, which means 3MHz, when activating the external resitor. Is it possible to change the DCO frequency simply to 48MHz (DCORSEL=5) afterwards?
  2. Is it required to set the calibration data CSDCOERCALx, when matching the nominal frequency?

Is it in generell required to have an external resistor to match an UART baud rate (115k)?

Thanks, Matthias

  • 0
    TI__Guru 63171 points
    Matthias,

    1. Yes. You would enable the external resistor before transitioning to a higher frequency. Please be sure to also adjust the flash wait states and core voltage to support 48Mhz.

    2. It is not required, but please note that the parameters found in the datasheet are with the calibrated frequency settings. Also note that there are two settings, one for range 5 and another for ranges 0-4.

    3. The resistor value is independent of the Baud rate. The recommended resistor value is 91Kohms, 0.1%, 25ppm/C. See Note 2 on page 51, www.ti.com/.../msp432p401m.pdf

    Please let me know if you have additional questions.

    Regards,
    Chris

**Attention** This is a public forum