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LAUNCHXL-F280025C: About eQEP and carrier frequency for adjusting dimming with PWM

Masaru Oinaga
Expert 3375 points
Part Number: LAUNCHXL-F280025C
Other Parts Discussed in Thread: DRV8262EVM,

Tool/software:

Hello, Team,

Our customer is currently using LAUNCHXL-F280025C with DRV8262EVM and have some questions.

  1. About the enhanced quadrature encoder pulse modules (eQEP) installed in F280025C;
    1. What does it mean by "it has a 32bit timer and 16bit capture"? Does this mean that it reads 32bit timer value into a 16bit capture resister?
    2. If so, it means that it cannot capture 16bit out of 32bit and this un-captured 16bit can be used somewhere else?
      (FYI, my customer is reading a Japanese manual from 2012 (link) so there might be some contradiction in what he is asking)
  2. What would be the usable carrier frequency range when using LED4 (GPIO31) and LED5 (GPIO34) to adjust dimming via PWM?

In addition, if there are useful materials which could help customer to understand C2000 and kick-start development, that would be very helpful.

Best Regards,
Masaru

  • +1
    TI__Mastermind 20586 points

    Hi Masaru,

    Masaru Oinaga said:
    • What does it mean by "it has a 32bit timer and 16bit capture"? Does this mean that it reads 32bit timer value into a 16bit capture resister?

    No it does not mean that the 32 bit timer into 16 bit capture register.

    Masaru Oinaga said:
    1. What would be the usable carrier frequency range when using LED4 (GPIO31) and LED5 (GPIO34) to adjust dimming via PWM?

    What carrier frequencies are they planning to use? 

    The eQEP has several submodules within it such as the Quadrature capture unit, Position counter/control unit (PCCU) and the Quadrature decoder (QDU).

    The 16 capture register (QCTMR) refers to the Edge Capture Unit in the eQEP. This value is responsible for capturing the time on every unit position event. The QCTMR is 16 bit and is latched to the 16 bit QCPRD register on every unit position event. The following snippet from the TRM mentions that the time measurement between unit positions events will be correct if the following condtions are met.

    The 32 bit timer or QPOSCNT is the one responsible for counting up or down on every eQEP pulse based on direction input. This value can be latched in the 32 bit QPOSILAT register when an index event occurs for example.

    Masaru Oinaga said:

    In addition, if there are useful materials which could help customer to understand C2000 and kick-start development, that would be very helpful.

    Here is academy link for eQEP labs: 

    1. https://dev.ti.com/tirex/explore/node?node=A__AQrUNT9kEosYkSfiQv8.gQ__C28X-ACADEMY__1sbHxUB__LATEST

    2. https://dev.ti.com/tirex/explore/node?node=A__AYuKeLONYZ4NJtiy3OplhQ__C28X-ACADEMY__1sbHxUB__LATEST

    Best regards,

    Ryan Ma

  • 0 in reply to Ryan Ma
    TI__Expert 3375 points

    Hello, Ryan,

    Thank you for the quick reply. Actually, our customer is trying to use it to control DRV8262EVM. I will include you in the loop and let us discuss this offline.

    Best Regards,
    Masaru