Max guidesA technician must decide whether microstep angle is safe before changing microsteps per quarter-cycle on the real device. The result is unresolved until the rule and units are checked. Predict the direction first.
See the relationship before changing it
Set the input, apply the rule, then read the result with its unit.
The retained audit below checks several chapter fixtures. This model keeps those stated values fixed and changes only microsteps per quarter-cycle, so the numeric fixture does not switch without explanation.
Derive the baseline in four named moves
- 1
Name the input. The chapter baseline is 16 steps.
- 2
Name the relationship. angle = 90 degrees / microsteps
- 3
Substitute with units. 90 / 16 = 5.625 degrees
- 4
Read the result. Keep the unit beside the value. Use it only inside the technical boundary on this page.
Predict, then change microsteps per quarter-cycle
Try Predict the direction of angle = 90 degrees / microsteps. Test another microsteps per quarter-cycle, then compare microstep angle.
Observe More microsteps divide the same quarter-cycle into smaller command angles. Reset microsteps per quarter-cycle to 16 and compare microstep angle.
Explain The driver subdivides the same coil-current phase rotation among more commands, so each microstep advances an inversely smaller electrical angle.
Check yourself
What should you do before trusting a moved-control result?
What does this small model leave out?
1. The driver commands current
A stepper driver compares the voltage across a small sense resistor with a reference. Microstepping changes that current target through sampled sine values.
2. Build the quarter-sine table
Split 90 degreesFor N=16, each electrical angle step is 90°/16=5.625°.
Sample the sineIk=Itrip sin(kπ/(2N)).
Subtract neighboursThe first and last current jumps are unequal.
3. Add the electrical lag
The chapter's 2.5 mH and 1.5 Ω winding has τ=1.67 ms, longer than the 1/800=1.25 ms command period.
4. Try the microstep count
TryChange the number of microsteps per quarter-cycle while the motor and 800 steps/s timing stay fixed.
ObserveAt 1/16 stepping, the angle is 5.625°, the first jump is 0.147 A, the last is about 0.007 A, and the first is about 20.4× larger. The winding reaches only 52.8% in 1.25 ms.
ExplainMicrostep count changes the sine-table increments and steps/revolution. The fixed L/R and command period separately bound how closely real current follows those targets.
The sine-table comparison fixes the motor's winding properties and the 800 steps/s command rate while microstep count changes, using a first-order response to one current target. It leaves out phase interaction, driver decay mode, supply headroom, voltage generated by motion, detent torque, load angle, resonance, driver nonlinearity, heating, and accumulated motion error.
- bipolar phase interaction
- Needs separate evidence
- chopper decay mode
- Needs separate evidence
- supply voltage headroom
- Needs separate evidence
- back-EMF
- Needs separate evidence
- detent torque
- Needs separate evidence
- load angle
- Needs separate evidence
- resonance
- Needs separate evidence
- driver nonlinearities
- Needs separate evidence
- heating
- Needs separate evidence
- cumulative motion error
- Needs separate evidence
Use field evidence or a deeper model before release.
5. Read the non-uniform steps
Sine is steep near zero and flat near its peak. Equal angle intervals therefore cannot produce equal changes in commanded current.
6. Verify motion, not just the table
Record sense resistance, current limit, supply, winding R/L, decay mode, step rate, load, temperature, missed steps, resonance, and measured position.
7. Check yourself
What voltage represents 1.5 A through 0.1 Ω?
Why is the first sine step larger than the last?
Does 3,200 commands/rev guarantee 3,200 positions?
The sine-table comparison fixes the motor's winding properties and the 800 steps/s command rate while microstep count changes, using a first-order response to one current target. It leaves out phase interaction, driver decay mode, supply headroom, voltage generated by motion, detent torque, load angle, resonance, driver nonlinearity, heating, and accumulated motion error.
- 1/16
- Driver microstep setting
- 200→3,200 steps/rev
- Full-step to microstep commands per revolution
- 5.625°
- Electrical angle per microstep
- 1.5 A
- Coil current limit
- 0.1 Ω
- Current-sense resistance
- 0.150 V
- Sense voltage at current limit
- 0.147 A
- First quarter-sine current increment
- about 0.007 A
- Last quarter-sine current increment
- 20.4×
- First-to-last current-increment ratio
- 1.67 ms
- Winding electrical time constant
- 800 steps/s
- Fixed microstep command rate
- 1.25 ms
- Time between microstep commands
- 52.8%
- Target current reached within one command period
They do not certify position or torque; Under the Hood keeps those limits.