I am currently using a the drv8834 and using the schematic used on the drv8834 pololu page. I am having an issue getting the vref voltage what I want it to be. I’m thinking the potentiometer is not working properly because when I change the potentiometer the vref voltage goes up and then down from about 0 mV to 60 mV and it’s constantly changing
Hello.
How are you measuring VREF? Can you describe (or post a picture showing) the two points on the board you are measuring the voltage from? If you are trying to measure the current limit reference voltage from the pin labeled REF, you need to bridge the VREF jumper by soldering a small wire across the indicated pads shown in the picture under the “Optional pin jumpers” section of its product page. Alternatively, you can measure VREF from the via that is circled on the bottom silkscreen of the board.
- Amanda
I used the via hole near the potentiometer and it was not giving my an exact voltage but it would gradually rise or fall and constantly varying
Can you post pictures showing all of your connections and some close up pictures of both sides of the board that show the soldered connections? If possible, a video showing how you are reading the VREF voltage would also be helpful.
- Amanda
I feel like I shouldn’t be getting this high of a voltage
You are right; that is a high VREF voltage reading for the DRV8834.
From the pictures you provided, it looks like some of your solder joints are not making good connection to the DRV8834 board, especially the GND pin for the motor power supply. Can you try touching up the solder to see if that helps? The solder joints should look like the ones shown in this soldering tutorial.
- Amanda
Ok I will try this and let you know my results. Thanks so much for the help. I can use the 5v from the pi as the motor supply correct?
I do not know the current specs of your stepper motor or which Raspberry Pi version you are using, so I do not know how much current it can output. In general, we recommend connecting the motor power inputs (VMOT and GND) directly to an external power source (e.g. LiPo batteries).
- Amanda