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Original question:

DRV2625: using drv2625 in RTP

DRV2625: can i use DMA when using RTP mode

jack bi
Intellectual 290 points
Part Number: DRV2625

Dear Ti expert,

    there is following descriptions in drv2625 datasheet,

    Question 1. how should i understand it?

    Question 2. can i use DMA(direct memory access) in RTP mode? thanks

     Because of the similarity between RTP mode and legacy PWM modes, any API (application-programming
interface) designed for use with a PWM generator in the host processor can write the data values over the I2C
rather than writing the data values to the host timer. This ability frees a timer in the host while retaining
compatibility with the original software.

  • 0
    TI__Guru* 84915 points

    Hi, Jack,

    This paragraph describes the similarity between the RTP mode and a processor with PWM generator. Basically, the RTP mode is controlled via I2C in order to configure the amplitude value to be used. Similarly, in the host processor, in order to modify the PWM value, you require to modify the data values of the host timer. So, instead of taking some time to modify the host timer in the processor, the datasheet recommends to modify the RTP amplitude value over I2C.

    Unfortunately, the DMA and RTP mode are independent modes and cannot be used at same time. The RTP mode and the DMA (in this case, the waveform sequencer mode) are configured with the register 0x07, bits 0-1.

    Please let me know if you require additional details on this. We will be glad to help you.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    Intellectual 290 points

    dear luis,

          thanks for your reply. so with instead of taking some time to modify the host timer in the processor, the datasheet recommends to modify the RTP amplitude value over I2C, you just mean something like PWM and SPWM? is my understanding right?

    in most cases, the pwm duty (in this case ,amplitude data) is variable. so in order to generate desired waveform, i think a timer is still needed which is used to decide when to change the amplitude data via i2c,right? many thanks

  • 0 in reply to jack bi
    TI__Guru* 84915 points

    Hi, Jack,

    Basically, the datasheet makes a comparison between the RTP and PWM/analog control of the DRV2625. In RTP mode, you modify the output duty cycle via I2C. In PWM mode, you modify the output by modifying the PWM input duty cycle too. So, both modes can be used in the same way if only a duty cycle change is needed. The datasheet recommends to use the RTP mode for this feature since its configuration its easier (just a command via I2C).

    Best regards,
    Luis Fernando Rodríguez S.