Configuration

Doppelstep is configured the Zephyr way. The devicetree describes the hardware: the power stage, the motor and its limits, the servo on its UART. Kconfig selects the compiled features, the threads and the buffers. Both are read at build time, so a change needs a rebuild (a pristine one for the devicetree and Kconfig). Settings that a host may change at run time, such as the ID or the baud rate, are servo registers (DYNAMIXEL emulation).

Where each setting lives

What	Where
Motor (R, L, rated current, back-EMF, steps), stage limits, control (microsteps, bandwidth, currents, velocity, acceleration)	Motor node, app/boards/<board>.overlay
PWM frequency, dead time, ADC channels, shunt, amplifier gain, VBUS divider	Power stage node, app/boards/b_g431b_esc1.overlay
DYNAMIXEL ID, factory baud, start position, gear, NVS partition	Servo node, a child of the UART
Threads, queues, offset samples, command timeout	CONFIG_SFS_*, app/Kconfig
Stepper-C build options (backend, topology, sine table, -O2)	CONFIG_SSTEP_*, modules/stepper-c/Kconfig
X430 model, devices per bus, protocol features	CONFIG_X430_* (Kconfig of the emulator)
Bus buffer, poll period, persistent storage, Reboot behaviour	CONFIG_SFS_DXL_*, drivers/x430/Kconfig
Simulated motor (model parameters, scenario, log)	CONFIG_SFS_SIM_*, app/sim.overlay (Simulated motor)
Board-specific Zephyr options (FPU, RTT, OPAMP; native_sim tick and logs)	app/boards/<board>.conf
Bootloader, flash layout, serial recovery	app/sysbuild.conf, app/sysbuild/, partitions in the board devicetree (Firmware update)

Open the Kconfig menu of a build with west build -d build -t menuconfig.

The motor node

The values for the 17HS19-2004S1 motor and the B-G431B-ESC1, from app/boards/b_g431b_esc1.overlay:

Property	Value	Meaning
phase-resistance-milliohm	1600	Coil resistance (datasheet)
phase-inductance-microhenry	3000	Coil inductance (datasheet)
rated-current-milliamp	2000	Rated phase current (datasheet)
back-emf-uv-s-per-rad	208600	Back-EMF constant
full-steps-per-rev	200	Full steps per revolution
vbus-nominal-mv, vbus-min-mv, vbus-max-mv	24000, 10000, 28000	Supply voltage: nominal and trip limits
trip-current-milliamp	3500	Overcurrent trip
aux-trip	set	Also trip on the shared leg W
slow-loop-hz	1000	Motion loop rate; the PWM rate must be an integer multiple
microsteps	16	Microsteps per full step
current-bandwidth-hz	1000	Bandwidth of the current controller
run-current-milliamp, hold-current-milliamp	1500, 500	Current while moving and at rest
hold-delay-ms	500	Time at rest before the hold current applies
max-velocity, max-acceleration	16000, 64000	Upper limits of every motion profile

The power stage node

Property	Value	Meaning
pwm-frequency	20000	PWM and fast-loop rate, Hz
dead-time-ns	0	Dead time of the half-bridges. Must be set before the outputs can be enabled (bring-up)
vbus-divider	18000, 169000	VBUS divider resistors, Ω
current-sense-invert	not set	Inverts the current measurement, if bring-up step 3 requires it

Shunt, amplifier gain and the ADC channels are in the same node; their values and the resulting full scale are in Hardware and bring-up.

The servo node

Property	Default	Meaning
factory-id	1	DYNAMIXEL ID while no EEPROM is stored and after Factory Reset
factory-baud-code	3 (1 Mbps)	Baud Rate register value, same conditions
start-position	2048	Present Position at power-on (no encoder)
gear-motor-revs, gear-joint-revs	1, 1	Gear ratio between motor and joint
storage	&storage_partition	Flash partition of the EEPROM area (NVS)

Variants of the build

Variant	Command
Board, real motor	west build -p always --sysbuild -b b_g431b_esc1 -s app -d build
Board, simulated motor	add -- -DEXTRA_DTC_OVERLAY_FILE=sim.overlay
PC (native_sim)	west build -b native_sim/native/64 -s app -d build-native
Fixed-point Stepper-C backend	add -- -DCONFIG_SSTEP_MATH_FIXED=y

sim.overlay stays in the CMake cache of a build directory, so a following incremental build keeps the simulated motor until the next pristine build.