Hello,
I'm trying to figure out how to measure how much current is actually being drawn by the stepper motor I'm using with the allegro A3979 driver. My current sense resistors are of 0.1 OHM each.
The spec for the motor I'm using are on the data sheet I've attached here. The A3979 is controlled by a microchip PIC24.
Right now I have my Vref (pin 8) set to ~1.5V. So by following the spec on the A3979 data sheet (page 7) for ITRIPmax I should have:
ITRIPmax = VREF/8RS
ITRIPmax = 1.5/(8*0.1) = 1.875A
Correct?
I've measured the voltage across both sense resistors R10 and R9 and it's about 20mA on each one. 20mA/0.1 = 200mA, way less current than 1.875A. I tried putting a scope across R10 and R9, but I didn't get anything on the scope. Maybe there is something I'm missing here. Oh and I have this set to Sixteenth Step micro-stepping with ms1 and ms2 set high.
Any help trying to help me figure this out will be appreciated. I'm trying to make a tutorial on this topic. I've made my board and everything already, just trying to "validate" my setup and verify it's operation.
I'm trying to figure out how to measure how much current is actually being drawn by the stepper motor I'm using with the allegro A3979 driver. My current sense resistors are of 0.1 OHM each.
The spec for the motor I'm using are on the data sheet I've attached here. The A3979 is controlled by a microchip PIC24.
Right now I have my Vref (pin 8) set to ~1.5V. So by following the spec on the A3979 data sheet (page 7) for ITRIPmax I should have:
ITRIPmax = VREF/8RS
ITRIPmax = 1.5/(8*0.1) = 1.875A
Correct?
I've measured the voltage across both sense resistors R10 and R9 and it's about 20mA on each one. 20mA/0.1 = 200mA, way less current than 1.875A. I tried putting a scope across R10 and R9, but I didn't get anything on the scope. Maybe there is something I'm missing here. Oh and I have this set to Sixteenth Step micro-stepping with ms1 and ms2 set high.
Any help trying to help me figure this out will be appreciated. I'm trying to make a tutorial on this topic. I've made my board and everything already, just trying to "validate" my setup and verify it's operation.
