Hello,
We've designed a STSPIN32F0251-based motor driver board, but when running the 6-step firmware algorithm, the motor aligns and then vibrates with a high-pitched sound. When we check the state-machine, we can see it reaches the RUN state after executing ALIGNMENT.
We probed the inverter output phases on both our custom board and the EVSPIN32F02Q1S1 evaluation board, observing significant differences in pulse width and voltage levels, despite using:
- The same user code
- The same PSU
- The same motor & encoder
Scope Captures
Custom Board:
- Channel 1 = OUTA
- Channel 2 = OUTB
- Channel 3 = OUTC
EVSPIN32F02Q1S1:
- Channel 1 = OUTA
- Channel 2 = OUTB
- Channel 3 = OUTC
- Channel 4 = Current Sense Amplifier Output
Board Modifications
To match the EVAL board, we made the following PCB modifications:
- RES5 pin grounded via flywire.
- V+ and V- on U2 were corrected by lifting the pins and flywiring to the correct nets.
There are more differences between the two boards, I detailed them here below and attached the schematic PDF.
EVSPIN32F02Q1S1 Designators MD V6.0 Designators Status Description
| Q1, Q3, Q4, Q6, Q7, Q9 | Q1, Q2, Q3 | Changed on V6.0 | Different inverter MOSFETs |
| R56, R42, R30, R18, R13, R3 | R30, R34 (ABC) | Changed on V6.0 | 100Ω → 10Ω Gate resistors |
| C26, C12, C3 | C47 (ABC) | Changed on V6.0 | 1uF → 120nF Bootstrap capacitor |
| R33 | R23 | Changed on V6.0 | 63.4kΩ → 17.2kΩ OC Resistor |
| R24 | R24 | Changed on V6.0 | 1kΩ → 2kΩ OC Resistor |
| R34, R36, R111 | R21 | Changed on V6.0 | 25mΩ → 15mΩ Shunt resistor |
| R41, C27, U2, C23, C24, R55, R52 | R12, R14, R15, R17, R18, R19, R22, C10, C11, C12, C15, C16, C18, U2 | Changed on V6.0 | Current sense circuit |
| C37, C38, C39 | C7, C8, C9 | Changed on V6.0 | 10pF → 50pF Encoder decoupling |
| D7, D4, D1 | D9 (ABC) | Newly Added to V6.0 | Bootstrap diode populated |
| R35, R15, R1 | R26 (ABC) | *Newly Added to V6.0 | |
| Changed on V6.0* | 27Ω → 10Ω Bootstrap resistor | ||
| R49, R40, R27, R16, R10, R2 | Missing from V6.0 | Discharge gate resistor | |
| D9, D8, D6, D5, D3, D2 | Missing from V6.0 | Discharge gate diode populated | |
| R103 | Missing from V6.0 | 0Ω resistor tying RES5 to GND | |
| R23 | Missing from V6.0 | Speed set resistor for debugging | |
| R26 | Missing from V6.0 | Speed set resistor for debugging | |
| C16 | Missing from V6.0 | Speed set capacitor for debugging | |
| C80, R67, R69, R78, R80 | Missing from V6.0 | Bus voltage sense circuit | |
| D10, D11, D12 | Missing from V6.0 | Encoder protection Schottky diodes | |
| R72, R81, C41 | Missing from V6.0 | Temperature feedback circuit |
Questions
- How should we interpret the waveform from our custom board? What steps should we take to align it with the EVAL board’s output?
- Why does the EVAL board’s current sense amplifier output appear as a flat DC signal? Shouldn’t it show a ramp-like waveform?
Any guidance would be greatly appreciated!
