DRV8805: Wave form pule widths

Ryan Porteous

Part Number: DRV8805

Hi, I'm trying to drive a stepper motor in the wave drive excitation mode. Looking to get 16.0 ms pulses at each phase at 61.04Hz, 100% duty cycle. Trying to figure out how to pulse the STEP line to achieve this.

I'm a confused on the timing correlation between STEP and the OUTPUTS. The image from the datasheet below seems to suggest that pulse the STEP high once turns OUPUT1 high and pulsing the STEP again brings OUTPUT1 low, while simultaneously bringing OUTPUT2 high? If I have rising edges on the STEP every 16ms does that achieve the wave drive I'm looking for? How long would I want the STEP to be high or low though in between.

over 4 years ago

0 Wang5577 over 4 years ago

TI__Guru 56650 points

Hello, Ryan,

The STEP pin timing picture shows the OUTx moves to next step value on every STEP pin voltage rising edge. The OUTx next STEP value follows the Table 2, Table 3, and Table 4. It could be same or flip from the previous value.

Regards,

Wang Li

0 Ryan Porteous over 4 years ago in reply to Wang5577

Prodigy 20 points

Okay, so the pulse duration of STEP being high or low does not matter. Only the frequency at which it goes from low to high (time between the rising edges).

+1 Wang5577 over 4 years ago in reply to Ryan Porteous

TI__Guru 56650 points

Ryan,

If the pulse duration of STEP being high or low timing is longer than the minimum STEP pin pulse width, yes, it doesn't matter.

I would recommend 50% duty cycle for STEP pin signal. So, tWH and tWL have even number.

Regards,

Wang

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DRV8805: Wave form pule widths