Setting VREF on DRV8825

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ryan
Posts: 2
Joined: Thu Jul 23, 2020 6:04 pm

Setting VREF on DRV8825

Post by ryan » Thu Jul 23, 2020 6:16 pm

Hello! I have a DRV8825 from Pololu, and in their instructions they say to avoid damaging the stepper and/or the driver, do not connect the stepper to the driver until after setting the correct VREF value [1]. However, the Raspberry PI CNC documentation under the Quick Start Guide [2] says, "WARNING: Do not power up the board with stepper drivers installed if they are not connected to stepper motors. The stepper drivers are current limiting and will overheat if they are not connected." I am not sure which one of these is correct.

I did attempt to set the VREF with power only applied to the RPi/CNC Hat, but there did not appear to be any voltage on the VREF for me to be able to make the adjustments.

- [1] http://www.youtube.com/watch?feature=pl ... 9BHS9hfSUk
- [2] https://wiki.protoneer.co.nz/Raspberry_ ... tart_Guide

ryan
Posts: 2
Joined: Thu Jul 23, 2020 6:04 pm

Re: Setting VREF on DRV8825

Post by ryan » Tue Jul 28, 2020 11:57 pm

I ended up pulling the stepper drivers and setting up a breadboard to set the VREF voltage.

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