• Small mobile robot / actuator controller prototype or production-intent module.
• External DC motor supply, nominal 12 V, with support for common robotics supply variation.
• Closed-loop speed and position control implemented in MCU firmware.

• Drive one brushed DC motor forward/reverse with PWM.
• Read quadrature encoder A/B and optional index channel.
• Measure motor current for telemetry and firmware overcurrent protection.
• Report motor-driver and power-good faults to the MCU.
• Provide SWD programming/debug, UART/control header, and status LEDs.

• Integrated H-bridge: NXP MC33926PNB, 5 V to 28 V motor supply class, 5 A peak-capable, PWM-compatible, current limit, short-circuit and thermal latch-off protection.
• MCU: STM32G431CBT6, 170 MHz Cortex-M4F control-oriented MCU with encoder-capable timers, PWM timers, ADC, USART, FDCAN-capable pins, and SWD.
• Current measurement: INA240A1D PWM-rejection current-sense amplifier across an inline 10 mΩ motor shunt, biased at midscale for bidirectional current.
• Encoder conditioning: SN74LVC3G17 triple Schmitt buffer, 3.3 V powered with 5.5 V tolerant inputs; per-channel pull-up/filter/series protection and ESD array.
• Power: 12 V nominal input with fuse/PTC, TVS, ideal-diode reverse-polarity MOSFET stage, and 3.3 V synchronous buck.

Diagram

• Power input/protection: 2-pin 5 mm terminal block, 3 A+ protection path, SMBJ33CA input TVS, LM74700 ideal-diode controller and 60 V low-RDS(on) N-MOSFET.
• Logic rail: LMR33630-Q1 buck configured for 3.3 V using datasheet 400 kHz component values.
• Motor drive: MC33926 with datasheet charge-pump capacitor, bulk VPWR capacitance, status/fault pull-up, slew-rate control, disable control, and motor-output TVS.
• Current sensing: INA240A1, 10 mΩ shunt, 3.3 V midscale reference, ADC output filter, Kelvin-routed shunt requirement for layout.
• Encoder input: 6-pin encoder connector carrying 3.3 V, GND, A, B, index, and optional shield/aux; Schmitt buffering protects MCU timing from cable noise.
• MCU/debug/control: STM32G431 SWD, reset, BOOT0 pull-down, UART/control header, status LEDs.

• J1: DC power input, nominal 12 V, expected operating design range 6 V to 24 V within motor-driver/regulator limits.
• J2: Motor output, bidirectional H-bridge output, 2 A continuous target.
• J3: Encoder input: 3.3 V, GND, ENC_A, ENC_B, ENC_Z, AUX/SHIELD.
• J4: SWD programming/debug: 3.3 V reference, SWDIO, SWCLK, NRST, GND, optional SWO.
• J5: Control UART/GPIO: 3.3 V, GND, UART_TX, UART_RX.

• External powered; no battery charger or runtime target on this board.
• Motor current dominates input current. Logic rail load is expected under 250 mA peak.
• Buck regulator selected instead of LDO to avoid thermal dissipation from 12 V input.

• SMD production-ready design with through-hole terminal/header connectors where mechanically useful.
• Layout must use heavy copper pours/traces for VMOTOR, H-bridge, shunt, and motor output.
• Thermal pad / exposed pad soldering and copper area are required for the MC33926 and power parts.
• Kelvin routing required for INA240 shunt inputs.

• Configure PWM outputs to MC33926 IN1/IN2 or disable-PWM strategy.
• Use encoder-capable timer channels for quadrature A/B.
• ADC samples INA240 current output and optional MC33926 FB output.
• Monitor motor-driver SF fault and buck PG.
• Fault handling must disable bridge on overcurrent, SF assertion, undervoltage/power-good loss, or firmware watchdog failure.

• Keep motor/power loop compact.
• Keep encoder/control connectors away from H-bridge switching nodes and motor terminals.
• Place input TVS/fuse/reverse protection near the power connector.
• Place current shunt inline with motor output and route INA240 Kelvin traces symmetrically.

• 12 V nominal supply selected as a common robotics voltage; selected ICs support wider operating ranges.
• Integrated H-bridge chosen over discrete H-bridge for safer fault handling and faster schematic completion.
• INA240 added for accurate bidirectional PWM current sensing; MC33926 FB kept as an auxiliary coarse current/fault-observability signal.
• Schmitt-buffered encoder input chosen for cable/noise robustness and 5 V tolerant conditioning.

• Encoder outputs are open-drain/open-collector or push-pull logic compatible with 3.3 V pull-ups / 5.5 V tolerant buffer inputs.
• Motor continuous current is 2 A; stall current can exceed this but is handled as a transient by driver current limiting and firmware shutdown.
• The control host can use 3.3 V UART-level signals.

• Initial specification created from the user’s request and datasheet-backed component selection.