Firmware Configuration Readout

MMC / sensorless FOC

STM32G474RE + X-NUCLEO-IHM16M1 (STSPIN830) motor bring-up firmware. Field-oriented control instrumented end-to-end over the mmc-proto link.

build release · MS6

target thumbv7em-none-eabihf

fw mmc-g474 · date 2026-07-13

Flash used

5.1%

26.7 / 512 KB

Static RAM

26.9%

34.4 / 128 KB

Core clock

170MHz

Cortex-M4F · single

Control rate

20kHz

50 µs ISR window

Resource Utilization measured from release ELF · arm-none-eabi-size

FLASH 0x08000000 · 512 KB (dual bank)26.7 KB / 5.1%

0128256384512 KB

.text 24.8 KB · .rodata 1.2 KB · .vectors 472 B · .data init 272 B — the entire Embassy + HAL + FOC + observer + protocol stack.

RAM (static) 0x20000000 · 128 KB34.4 KB / 26.9%

0326496128 KB

BURST profiler buffer · 32 KB all other static · 2.4 KB free for stack / growth · ~93 KB

One [f32; 4096·2] capture buffer is 93% of static RAM. It only holds (i_d, v_d) pairs during an R/L probe — gate it behind a feature and the resident footprint drops to ~2.4 KB. No heap: allocation is fully static, single executor thread, panic-halt.

Platform & Build

MCU: STM32G474RE
Core: Cortex-M4F @170 MHz
Clock tree: HSI16 /4 ×85 /2
Flash: 512 KB dual-bank
RAM: 128 KB
Framework: Embassy async
embassy-stm32: 0.6.0
Runtime: no_std · no alloc
Profile: LTO · cg-units 1 · O2
Runner: probe-rs

Control & Front-End

PWM: TIM1 center-aligned
Carrier: 20 kHz ARR 4250
Loop rate: 20 kHz 50 µs
Max duty: 0.85
ADC: ADC1 42.5 MHz
Sensing: 3× shunt, injected
Shunt: 0.33 Ω 0.504 V/A
VBUS: ÷ divider ×16
Link: LPUART1 VCP
Baud: 1 Mbaud COBS

Motor Characteristics Stage F0 bench fit

Parameter	Value	Confidence
Pole pairs p	7	fixed
Stator R R_s	1.00 Ω	locked-rotor
Apparent R R'	0.97 Ω	rotating fit
Stator L L_s	0.10 mH	design center
Flux linkage λ	0.894 mWb	±0.04
Inertia J	0.31 µN·m·s²	rough
Friction	0.8 mN·m	est.

L was ill-conditioned in the rotating sweep (0.05 ± 0.10 mH — the I-f hang angle near π/2 hides it); 0.1 mH is a robust center that only sets the current-PI zero. J is the least-trusted number, so the speed loop is tuned conservatively.

Tuning Setup

Current loop · pole-zero

Bandwidth: 1 kHz rad/s ω
K_p = L·ω: 0.10
K_i = R·ω: 1000

Speed loop

~ω_bw: 40 rad/s el
K_p: 2.0e-4
K_i: 2.0e-3
i_q limit: ±0.8 A

Sensorless

Observer: flux + PLL
I-f handoff: 150 rad/s el

Drive Modes

Off

Stage disabled, phases Hi-Z

Open-loop voltage

Forced-frame V·∠ω_et { volts, omega_e }

I-f current

Forced-frame current, i_q live-adjustable { amps, omega_e }

Sensorless ← closed loop

I-f start → blend → observer + speed loop { amps, omega_e }

R/L probe

Locked-rotor identification (bench test)

State channel:

OFF RUN FAULT_OC FAULT_DRV FAULT_VBUS CAL SL_RAMP SL_BLEND

Profiler / Auto-Tune MS6

Measure → fit → write back, entirely over the protocol. The R/L probe aligns the rotor, square-wave excites the d-axis, and captures every ISR tick at full 20 kHz into the burst buffer; the host fits R/L and pushes new gains back live.

Align time: 300 ms
Excitation ½-period: 1.6 ms · 32 tk
Capture: 4096 pairs @20 kHz
Records: i_d, v_d

Live-writable parameters (RAM)

rlflux cur_bwspeed_kpspeed_ki

Each write is range-checked before it reaches the loop; a new value applies at the next clean drive start.

Protection & Limits

Overcurrent trip: 1.5 A · 2 samples
VBUS window: 5 – 30 V
Driver fault: EN_FAULT open-drain
Deadman: 2.0 s silence
Boot cal: 8192 tk · 0.41 s
V amplitude: ≤ 3.0 V
I amplitude: ≤ 1.0 A
ω_e ceiling: 2000 rad/s
Slew ω · V · I: 500 · 5 · 2

Telemetry

Channels: 18
Stream default: 1 kHz ÷20
Transport: COBS / mmc-proto
Burst capture: 20 kHz i_d, v_d
ISR watchdog: ISR_MAX_CYCLES

Live channels

iq_refi_di_q v_dv_q duty_aduty_bduty_c omega_mtheta_evbus i_ai_bi_c state theta_estomega_esttheta_err

Observer estimates (highlighted) stream alongside their measured counterparts, so every capture doubles as a shadow-validation of the sensorless stack.