Tethered Mini Drone Design

Thought for 1 min 23 sec

Routing preflight found C2 and D1 inside the bottom-left mounting-hole keepout. Routing cannot preserve both the approved placement and the required Ø8 mm mechanical clearance; moving those two parts is the recommended fix.

dacre

Move C2 and D1 clear

Worked for 1 hr 1 min

flux

The autorouter connected 125 of 134 initial airwires, and surgical routing reduced the remainder to six. The remaining pins are physically blocked by the approved placement/existing copper, so further retries without changing placement or deleting working routes would not converge; I’m running the final DRC summary now.

Worked for 1 min 22 sec

flux

Routing is substantially complete: 753 trace segments and 154 vias were added, with no overlapping-copper, via-in-pad, dangling-trace, or redundant-trace errors.

Open items

6 airwires remain:
- EFUSE_OVP: U2 OVP → R5
- 3V3: U4 VOS → existing 3V3 via
- Four ground-plane connections around U6, C13, and R3
These remained blocked after two targeted attempts; finishing them requires local copper rip-up and likely small placement adjustments.
Non-blocking placement advisories remain for five decoupling loops and the U3→L1 switch-path detour.

Suggested next steps

Authorize surgical movement around U2/U4/U6 and local trace rip-up to clear the six airwires.
Re-run full DRC and power-integrity checks.
Reconcile the routed PCB against the frame and USB-C cable clearance.

Waiting for input

Files

Schematic

Layout

3D View

Board Bring-Up Plan

Safety Setup

No propellers fitted for electrical bring-up.
Use a current-limited dedicated USB-C PD source or bench setup that preserves correct USB-C negotiation.
Keep PA12 / motor-rail enable low until the protected input and 3.3 V rail are verified.

Test Points

Table

Test point	Net
TP1	VBUS_RAW
TP2	9V_PROTECTED
TP3	4V_MOTOR
TP4	3V3
TP5	GND
TP6	MCU_NRST
TP7	SWDIO
TP8	SWCLK
TP9	IMU_SCK
TP10	MOTOR_RAIL_ENABLE

Staged Procedure

Inspect polarity, solder bridges, exposed-pad joints, and USB-C shield/ground continuity.
With power removed, measure resistance from VBUS_RAW, 9V_PROTECTED, 4V_MOTOR, and 3V3 to GND; investigate any low resistance.
Apply USB default power with the motor rail disabled. Verify 3V3 regulation and stable NRST.
Attach SWD and load firmware that leaves all motor PWM pins low and PA12 low.
Verify HUSB238A communication, request 9 V, and confirm TP1 rises to the negotiated voltage.
Confirm TP2 follows through the TPS25940, fault is inactive, and PA0 current telemetry is plausible.
Verify IMU identity, SPI traffic at TP9, stationary acceleration magnitude, and gyro bias stability.
Assert PA12 with no motors connected. Confirm TP3 is approximately 3.97 V and PB5 indicates power good.
Connect one motor at a time without a propeller. Run a low-duty PWM sweep and inspect gate, drain, rail ripple, and fault behavior.
Repeat for all four channels, then test controlled simultaneous loading while monitoring input current, converter temperature, cable droop, and PD stability.
Fit propellers only on a guarded thrust stand. Characterize each motor/prop pair before any flight attempt.

Acceptance Gates

No unexpected motor twitch during reset, flashing, or PD renegotiation.
3.3 V remains within tolerance during motor switching.
9 V contract remains stable under the planned aggregate command ceiling.
Motor rail and protection parts pass a supervised two-minute thermal test.
Firmware disarms within one control cycle on each injected fault.

Safety Setup
Test Points
Staged Procedure
Acceptance Gates