Building Your Micro 8520 with Navi3D Drone Studio

This guide walks you all the way from a freshly assembled airframe to a calibrated, tuned, flight-ready Micro 8520 — using nothing but a browser and Navi3D Drone Studio. You won't touch a command line or an IDE. Every step below maps to a tab inside the studio.

The Micro 8520 is a small indoor-class quadcopter: coreless 8520 brushed motors driven over 16 kHz PWM, a Teensy flight controller, an LSM6DSOX IMU, a Time-of-Flight sensor for ground cushion, and (on the PRO) an optical-flow sensor for position hold. It runs on a single 1S LiPo cell.

Before you start, a safety habit: keep propellers OFF until the very end of this guide. Every calibration, sensor check, and motor test in the studio is designed to be done with bare motors. Props go on only when you're ready for the first hover.

What You'll Need

• A Chromium-based browser (Chrome, Edge, Brave, Arc). Web Serial — the technology that lets the studio talk to your drone over USB — does not work in Firefox or Safari.
• A data-capable USB cable. Charge-only cables are the single most common reason a drone "won't connect." If you're not sure, use a cable you know transfers files.
• A fully assembled Micro 8520 with the Teensy flashed (we'll do the flashing) and the battery available.
• A flat, stable surface for calibration (a desk that doesn't wobble) and a soft surface (a folded towel or foam pad) for the vibration test.

Step 1 — Assembly

[ASSEMBLY SECTION — to be added separately] This is where the physical build lives: frame, motors, motor direction/wiring, the Teensy flight controller, the LSM6DSOX IMU mounting, the ToF (and OptiFlow on the PRO), the receiver, and the 1S power lead. Once the airframe is built and the Teensy is connected via USB, continue from Step 2.

After assembly, plug the drone into your computer with the USB cable and open navi3d.in/drone-studio in your browser. The studio opens on the Drone Selection tab.

Step 2 — Select Your Airframe

On the Drone Selection tab you'll see a card for each supported model. Pick the one that matches your build:

• Micro 8520 — coreless motors, ToF sensor.
• Micro 8520 PRO — adds optical-flow positioning on top of the ToF.

Clicking the card opens the Hardware Configuration page for that model. From here you'll flash firmware and open the data link. The left panel lists the firmware you can flash; the right panel is where you open the serial connection.

Step 3 — Flash the Firmware

The studio offers two firmware images for the Micro 8520, and you will use both at different points:

For a brand-new build, start by selecting Teensy Micro FC (Brushed) and clicking FLASH FIRMWARE. The studio puts the Teensy into program mode and uploads the image; it reboots automatically in a few seconds.

Good news about calibration data: the two firmware images share the same on-board storage layout. Anything you calibrate with one is read by the other. So you can calibrate with one image and fly with the other and nothing is lost — including after a future firmware update.

Step 4 — Establish the Serial Link

On the right side of the Hardware Configuration page is the Serial Connection panel.

1. Leave Port Selection on USB VCP (Browser Prompt).
2. Leave Baud Rate on 500000 (Teensy). Don't change this.
3. Click ESTABLISH SERIAL LINK.
4. Your browser shows its native device picker. Choose the Teensy from the list and confirm.

When the link opens, the connection dot at the top-right of the studio turns green, and live data begins streaming. If you've connected once already in this browser session, you can use LISTEN & ENGAGE to skip the picker.

If the dot stays red: it's almost always the cable (swap for a data cable), the wrong device picked from the browser dialog (re-open and choose the Teensy), or — on Linux — missing Teensy udev rules.

Step 5 — Pre-Flight Sensor Check

Open the Sensor tab. This is your live ground-station dashboard — read-only, just for confirming the airframe is healthy before you touch anything else. Walk through each panel:

• Attitude (IMU) — tilt the drone by hand. The artificial horizon and the pitch/roll/yaw numbers should respond smoothly. If they stay frozen at zero, the IMU isn't initializing — re-check the LSM6DSOX wiring before continuing. (The VIEW 3D button shows a 3D model in the same orientation, handy for confirming the IMU is mounted the way the firmware expects.)
• Power System — the voltage should match your charged 1S pack. A voltage that's clearly wrong usually means a battery-lead or divider problem.
• System Status — should read live (not DISCONNECTED).
• Receiver Input — power on your transmitter and move the sticks. The on-screen stick dots and the channel values (1000–2000) should track your inputs. Confirm your arm/disarm switch and flight-mode switch show up on the right channels.
• Barometer / ToF — point the drone's ToF sensor at the floor; the altitude should read a sensible distance. A FAULT tag means the studio isn't getting valid range data — check the sensor wiring and that nothing blocks its view of the ground.
• Optical Flow (PRO only) — hold the drone over a textured surface; the quality score should climb. Flow needs visible texture and decent light; a blank white floor gives a poor reading.

Only move on once the IMU responds, the battery reads correctly, and the receiver tracks your sticks.

Step 6 — Calibrate the Accelerometer (6-Point)

This is the most important setup step, and it lives on the Analysis tab. An uncalibrated IMU will think it's level when it's slightly tilted, and the drone will drift. Calibration measures and corrects that.

First, flash the Teensy Hardware Calibration firmware (Drone Selection → Flash) and re-establish the serial link, then return to Analysis.

1. Click MICRO ACCELEROMETER CALIBRATION. The wizard opens with a 3D model showing the pose it wants.
2. The studio asks you to rest the drone in six orientations, one at a time. A guided animation shows each pose:

• Point 1 — Flat (on its belly)
• Point 2 — Upside down
• Point 3 — Nose down
• Point 4 — Tail down
• Point 5 — Left side down
• Point 6 — Right side down

1. For each pose: place the drone exactly as shown, hold it dead still, and let the studio sample. If you bump it, the studio rejects that sample and asks you to retry — just hold steadier.
2. After all six poses, the studio computes the calibration and writes it to the Teensy's storage.

Two things make calibration fail: skipping a face (the studio will say it doesn't have enough coverage — re-pose and re-sample), or movement during a sample (any tremor gets the sample thrown out). Use a solid surface, set the drone down gently, and let go before each capture.

Step 7 — Measure the Mount Trim

Even after a perfect 6-point pass, the IMU chip sits on a board that's screwed into the frame, so there's always a fraction of a degree of physical tilt between "the sensor's level" and "the airframe's level." Mount trim cancels that out so the drone hovers flat instead of drifting.

The wizard continues straight into the trim measurement:

1. Rest the drone perfectly level on a flat, stable surface and follow the prompt to capture Position A.
2. When asked, follow the prompt for Position B (the studio guides the orientation).
3. The studio computes the residual tilt, saves the trim, and shows you the final pitch/roll trim values.

When this finishes, your IMU is honest. You can confirm the stored values any time on the Tuning tab under the EEPROM Calibration Matrix — the badge there flips from UNCALIBRATED (DEFAULTS) to showing your real offset, scale, and trim numbers.

Step 8 — Run the Motor Noise Sweep

Still on the Analysis tab, this checks the mechanical health of your assembled airframe. Motor imbalance, a bent prop, or a loose frame shows up as vibration that the flight controller will chase in the air, making the drone twitchy.

1. Place the drone on a soft surface — a folded towel or foam pad, NOT a hard desk (hard surfaces ring at motor frequencies and pollute the reading).
2. Click RUN MOTOR NOISE SWEEP.
3. The studio spins the motors through a low-throttle range and measures the resulting Gyroscope Angular Noise and Accelerometer Linear Noise, then reports an Airframe Status.

A clean Micro 8520 reads low noise and an "Optimal / Ready for Flight" status. If it reports excessive vibration, fix the mechanical cause before flying — most often a bent prop, a damaged motor, or a hardened/cracked foam mount. Re-run until it's clean.

The sweep also doubles as a motor-sync check: in the Motor Synchronization panel, all four motors should ramp together. A motor that lags or won't spin is a wiring or connection issue to fix first.

Step 9 — Test the Motors

Now flash the Teensy Micro FC (Brushed) firmware again (Drone Selection → Flash → re-establish link) and go to the Sensor tab.

In the Motor Feed panel, each motor (M1–M4) has a Test button. With props still off:

1. Tap Test on each motor in turn.
2. Confirm the correct motor spins, and note its rotation direction.
3. Verify each motor's spin direction matches your intended layout (the standard X-quad diagonal pattern).

If a motor spins the wrong way or the wrong motor responds, that's a wiring/order issue to correct now — long before props go on.

Step 10 — Tune the Flight Controller

Open the Tuning tab (Flight Dynamics Tuning). This shapes how the drone behaves in the air. The page is interactive only while connected.

Live PID Tuning (left card) — a 3×3 grid of Roll / Pitch / Yaw against P / I / D. These govern how aggressively the drone holds and follows your commands.

• Start from the studio's defaults for the Micro 8520.
• Use APPLY (RAM) to try values in the air without committing them — power-cycling discards them. This is the safe way to test a change.
• Use SAVE (EEPROM) only once you're happy, to make the values permanent.

The Live PID readouts at the top show the controller's current effort. With the drone still on the bench they should sit near zero; give it a gentle nudge by hand and you should see the matching axis spike and settle. That confirms the loop is closing without arming.

A sensible first-tune order is P → D → I, one axis at a time, Roll first.

Altitude & Position Hold (right card — mainly the PRO):

• ALT PID drives throttle from the ToF altitude.
• POS PID drives lean from optical-flow drift.
• Flight Envelope sets the limits: Climb Max (default 0.8 m/s), Hover (DSHOT) (the throttle the airframe hovers at; a closer value means a gentler takeoff), and Vel Max (default 0.8 m/s).
• Optical Flow Calibration (Swap X/Y, Invert X/Y, Pos Inv Pitch/Roll) re-orients the flow sensor onto the airframe. If position-hold pushes the drone the wrong way during a gentle nudge test, flip the matching invert.

Both cards have their own Apply/Save buttons that behave the same way.

Step 11 — First Flight

Now — and only now — fit the propellers, check they're on the correct motors and oriented correctly, and use a fresh charged 1S pack.

1. On the Sensor tab, confirm the battery reads full and the receiver tracks your sticks.
2. Arm using your transmitter switch.
3. Lift off gently to a low hover and feel the response.
4. Land, and use APPLY (RAM) on the Tuning tab to adjust gains between short flights. Re-fly, re-adjust, then SAVE what works.

Two or three short trim flights are usually enough to lock in a Micro 8520.

Step 12 — Review the Flight in Blackbox

After each flight, open the Blackbox tab and click REQUEST FLIGHT LOG. The studio pulls the recorded flight off the drone and plots it.

The most useful view is Roll with all four traces visible:

• SETPOINT — what you commanded.
• GYRO — what the drone actually did.
• PID — the controller's effort.
• ANGLE — the integrated attitude.

Read it like this:

• GYRO tracking SETPOINT closely with quick settling = well tuned.
• A steady gap between SETPOINT and GYRO = needs more I.
• Fast wobble on GYRO around a steady SETPOINT = too much P or D, or leftover mechanical vibration (re-check Step 8).
• Sluggish response to a stick input = needs more P.

Blackbox is the feedback loop for Step 10 — fly, read the log, adjust on the Tuning tab, repeat.

Step 13 — Plan a Mission (Optional)

Once the drone flies well, the Map tab lets you plan autonomous flights. Drop waypoints (each with its own altitude), review them in the Mission Planning panel, and use UPLOAD TO FC to send the route. The on-screen TAKEOFF, RTH (RETURN), and LAND buttons issue flight commands. Note that waypoints are not stored across power cycles — re-upload before each mission.

Quick Build Checklist

1. Assemble the airframe and connect the Teensy over USB. (Assembly section — separate.)
2. Drone Selection → pick Micro 8520.
3. Flash Teensy Micro FC (Brushed), then Establish Serial Link (500000 baud).
4. Sensor → confirm IMU, battery, receiver, ToF (and flow on PRO).
5. Flash Teensy Hardware Calibration, reconnect.
6. Analysis → 6-point accelerometer calibration.
7. Analysis → mount trim (Position A + B).
8. Analysis → motor noise sweep (on a soft surface).
9. Re-flash Teensy Micro FC (Brushed), reconnect → Sensor → test motors (props off).
10. Tuning → set PIDs (Apply in RAM, then Save).
11. Fit props → first hover → trim with Apply/Save.
12. Blackbox → review and refine.
13. Map → plan missions (optional).

Troubleshooting

Connection dot stays red. Charge-only cable, wrong port chosen in the browser dialog, or (Linux) missing Teensy udev rules.

IMU shows zeros and won't respond. The LSM6DSOX isn't initializing — re-check its wiring, then power-cycle.

Calibration says "not enough coverage." You missed one of the six faces or two poses were too similar. Reset and redo all six, each on a different physical side.

Calibration keeps rejecting samples ("movement detected"). The drone moved during capture. Use a solid surface and let go before each sample.

Motor noise sweep reports excessive vibration even with new parts. Run it on a soft surface, not a hard desk — hard tabletops ring and corrupt the reading. If it's still high, suspect a bent prop, damaged motor, or loose frame.

Drone drifts in hover after calibration. Re-run the mount trim (Step 7) on a confirmed-level surface; this is exactly what trim corrects.

Position hold (PRO) pushes the wrong way. Flip the matching Invert in the Optical Flow Calibration on the Tuning tab.

Tuning right-card is greyed out ("Hardware Offline"). You need a live serial link to edit altitude/position-hold gains — connect first.

This guide covers building and setting up the Micro 8520 with Navi3D Drone Studio (Beta 0.1.0). The physical assembly section is maintained separately.