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[FAQ] DRV2624: RTP Mode vs PWM Mode for DRV26XX Haptic Drivers

Part Number: DRV2624
Other Parts Discussed in Thread: DRV2604, , DRV2603

What is Real Time Playback (RTP) Mode?

-  RTP is based on the processor communicating the haptic waveform wanting to be played through I2C communication. Digital amplitude values are sent through the I2C interface to a specific register and the driver outputs that register’s amplitude value until it is updated by the host processor. This gives a way of having direct control over the haptic waveform instead of the chip playing waveforms stored in the internal RAM or ROM.

What is PWM Mode?

-  Pulse Width Modulation (PWM) Mode is based off providing the waveform data via the duty cycles percentages contained in the PWM signal from the processor, the duty cycle % is then translated by the driver to an amplitude value to be outputted. The PWM frequency can range from 10kHz to 250 kHz.

Which DRV26XX chips contain which modes?

-  RTP mode is supported by the DRV2604/05 and DRV2624/25 chips

-  PWM mode is supported by the DRV2603 and DRV2604/05 chips

How are these modes similar?

-  They both allow the haptic waveform to be controlled in real time via the host processor, just using two different communication protocols

How to transition from using PWM mode to RTP mode?

-  Instead of generating a PWM signal using timers within the host processor, take the digital values that get sent to the timers that determine duty cycle percentage which then determine waveform amplitude, and send them directly to the chip via I2C so that they determine the amplitude values directly using the RTP mode of the chip.

What are the advantages of using RTP mode over PWM mode?

-  It is a more direct form of communication and requires less work by the host processor, as the usage of timers is no longer required.