mohan-bee/pcb
This circuit integrates an ESP32 microcontroller with an IMU sensor and power management components, using multiple capacitors, resistors, and MOSFETs for motor control, while managing power supply and battery connections.
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- 1.0.0
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docs/flight-plan.md
**Yes—an ESP-based microdrone can fly smoothly. For your single-PCB build, I would choose an ESP32-S3, a supported SPI IMU, four 716 brushed motors, and 46 mm propellers.** The image above is Espressif’s reference-drone style, not a render of your proposed PCB. Espressif’s own hardware reference uses the same **716-motor + 46 mm-propeller class**, so this is a sensible starting point rather than an arbitrary combination. ([Espressif Systems][1])
The important distinction: **good components make smooth flight possible; matched propulsion, clean power, firmware timing, and tuning make it happen.** I would not promise “zero lag” or perfect hovering from a component list alone.
I’ve put the component selections, sourcing links, supporting circuitry, and mechanical checks into a workbook:
**[Download the drone component plan and BOM workbook](sandbox:/mnt/data/Tiny_ESP_Drone_Component_Plan.xlsx)**
## 1. My selected main electronics
For this version, I would move away from the earlier ESP-12F approach and use:
> **ESP32-S3-MINI-1-N8 + ICM-20602 over SPI + four AO3400A motor switches + TPS63031 3.3 V power supply.**
### JLCPCB sourcing
These are the **stock figures reported by JLCPCB’s public listings/search snapshots checked on 12 September 2026**. They are not reserved quantities or a checkout confirmation; JLC’s dynamically loaded inventory was not consistently exposed when opening the pages.
| Function | Exact component | JLCPCB code | Quantity | Reported stock | Listed unit price |
| ------------------------------ | ---------------------------- | -----------: | -------: | -------------: | ----------------: |
| **ESP controller** | **ESP32-S3-MINI-1-N8** | **C2913206** | 1 | 4,997 | US$4.6743 |
| **IMU** | **TDK InvenSense ICM-20602** | **C97633** | 1 | 5,436 | US$6.2652 |
| **3.3 V buck-boost regulator** | **TPS63031DSKR** | **C15516** | 1 | 6,592 | US$1.1645 |
| **Motor switching MOSFET** | **Alpha & Omega AO3400A** | **C20917** | 4 | 987,885 | US$0.0847 each |
| **Motor flyback diode** | **MDD SS34** | **C8678** | 4 | 5,123,772 | US$0.0349 each |
Sources, in table order: ESP module, IMU, regulator, MOSFET, and diode. ([JLCPCB][2])
That is approximately **US$12.58 for these core electronic components**, before supporting passives, PCB fabrication, assembly, shipping, and taxes.
**Assembly warning:** the selected ESP module and ICM-20602 are listed as **Standard PCBA only**. Do not budget this as a basic “US$2 PCB” order; get a complete assembly quote before committing. ([JLCPCB][3])
### Why these particular parts?
**ESP32-S3 rather than ESP8266/ESP-12F:** ESP-FC recommends ESP32/ESP32-S3, while its ESP8266 support is no longer actively developed. For a new performance-focused board, I would start on the supported platform. The MINI module also lets you avoid designing the bare chip’s flash, crystal, and RF circuitry yourself. ([GitHub][4])
**ICM-20602 rather than QMI8658A:** I know you previously preferred QMI8658A. For this build, firmware compatibility matters more than saving a few dollars: ESP-FC explicitly lists **ICM20602**, while QMI8658 is not in its supported-IMU list. ICM42688 is also supported, but I could not reliably confirm its JLC stock, so it is not my final selection. ([GitHub][4])
**AO3400A:** its on-resistance is specified at a **2.5 V gate drive**, making it a reasonable candidate for switching these motors from 3.3 V GPIO. Still, its headline current rating is not a guarantee that a tiny PCB footprint will stay cool—test it with your actual propeller load. ([Alpha & Omega Semiconductor][5])
---
## 2. Motors, propellers, and battery to buy
### My propulsion selection
| Part | Selected specification | Quantity for one drone | Store and observed availability |
| -------------- | --------------------------------------------------------------------------------- | ---------------------: | ---------------------------------------------------------------------- |
| **Motors** | **716 brushed coreless, 3.7 V, 7 × 16 mm body, 0.8 mm shaft; two CW and two CCW** | 4 motors | **iFuture:** ₹120 listing, marked in stock |
| **Propellers** | **46 mm, 0.8 mm mounting hole, CW/CCW pair** | 2 pairs | **RC Market City:** ₹40 per pair, marked in stock; code **RMC-700075** |
| **Battery** | **YY702030, 1S 400 mAh, seller-rated 30C, ordinary 4.2 V LiPo** | 1 | **Quartz Components:** ₹237; **67 listed in stock** |
Motor specifications and listing: iFuture. Propeller dimensions, pairing, and availability: RC Market City. Battery specifications and availability: Quartz Components. ([iFuture Technology][6])
**One procurement issue needs resolving:** iFuture’s page says “CW+CCW pair” near the purchase button, but its detailed package section says one motor. **Ask them to confirm that your order contains two CW and two CCW motors before paying.** I would also buy a spare set and compare the motors rather than assume every generic 716 performs identically. ([iFuture Technology][6])
### Why I selected separate 46 mm props
The listed motor shaft is **0.8 mm**, and these props explicitly specify a **0.8 mm hole**. Their diameter is also the default size in Espressif’s 716-motor reference. This is a better-defined starting point than using whatever unlabelled propellers happen to arrive with the motors. **Do not enlarge or drill the propeller holes to make a mismatched set fit.** ([iFuture Technology][6])
### Battery details that matter
The selected battery is **7 × 20 × 30 mm**, with an **M.X2.0 female connector** and **4.2 V maximum charging voltage**. Do not assume its connector is interchangeable with PH2.0 or BT2.0; confirm the mating connector and polarity before designing that connection. ([QuartzComponents][7])
Espressif’s reference specifies 300 mAh, with 350 mAh as an option. The **400 mAh pack is my currently sourced option**, not a claim that a larger battery automatically improves flight. Weigh it and include it in the thrust test before freezing the PCB shape. ([Espressif Systems][1])
**The unresolved performance variable is the generic motor batch:** the seller does not provide a verified thrust curve for this exact motor–propeller combination. I would approve it for flight only after measuring thrust and current.
---
## 3. The supporting circuit your PCB needs
The five main electronic parts are **not** the whole circuit.
### Power architecture
```text
1S LiPo battery
│
├── Battery rail ── four motors
│ │
│ four MOSFET switches
│
└── TPS63031 ── regulated 3.3 V
├── ESP32-S3
└── ICM-20602
```
**The motors must not run through the 3.3 V regulator.** The TPS63031 supplies the controller and sensors. TI specifies up to **500 mA output in boost operation with input above 2.4 V**, and up to **800 mA in buck operation under its stated conditions**—not an unconditional 1 A output. Check the 3.3 V rail with the radio active and the motors starting. ([Texas Instruments][8])
### Required supporting parts
| Circuit area | What to include | Component reference / status |
| --------------------------------- | ------------------------------------------------------------------------------- | ------------------------------------------------------------ |
| **MOSFET gates** | Four **100 Ω series resistors** | **C22775**, 0603; catalog entry verified |
| **Motors off during reset** | Four **100 kΩ gate-to-ground resistors** | **C25803**, 0603; catalog entry verified |
| **Battery measurement** | Two **100 kΩ resistors** and an ADC filter capacitor | Same **C25803**; divider produces 2.1 V from a 4.2 V battery |
| **Boot/reset/chip-select pulls** | Appropriate **10 kΩ resistors** | **C25804**, 0603; finalize count after schematic |
| **Reset timing** | Appropriate EN timing capacitor | **C15849**, 1 µF candidate |
| **Regulator capacitors** | TI reference starts with **10 µF input, 2 × 10 µF output, and 100 nF at VINA** | Check effective capacitance after DC-bias derating |
| **Regulator inductor** | **1.5 µH shielded power inductor**, low resistance, adequate saturation current | **Final stocked MPN still needs selection** |
| **IMU/module bypassing** | Capacitors at the required supply/reference pins | Follow the exact manufacturer reference circuits |
| **Motor-noise suppression** | Provision for small ceramic capacitors at the motor terminals | Fit and evaluate during noise testing |
| **Battery-rail bulk capacitance** | Provision for a low-ESR capacitor near the power entry | Final value/package after transient and mass checks |
| **Programming** | GND, 3V3, TX, RX, EN and BOOT test pads | External programmer; no onboard USB-UART needed |
The resistor/capacitor candidate identities come from JLC’s catalog; the regulator’s reference values come from TI. **I could not independently verify current inventory for every supporting passive**, so those are explicitly marked separately in the workbook rather than presented as an order-ready manufacturing BOM. ([JLCPCB][9])
For each motor, the flyback diode goes **across the motor**: cathode to battery positive, anode to the MOSFET drain/motor-negative connection. The MOSFET is the low-side switch. Have this power stage and its thermal/current capacity reviewed before ordering.
I would omit **onboard charging, a camera, GPS, displays, and big connectors** from version one. First make the light, clean flight-control board work.
---
## 4. PCB and 3D-printed mechanical design
These are **my proposed design targets**, not measurements from a finished drone.
| Feature | Proposed target |
| ------------------------------ | --------------------------------------------------------------- |
| Configuration | **Quad-X, single PCB** |
| PCB construction | **4 layers, around 1.0 mm thick**, subject to stiffness testing |
| Assembly | **All electronic components on the top side** |
| Opposite-motor centre distance | **80 mm diagonal** |
| Propellers | **46 mm** |
| All-up mass | **Aim for 30–35 g**, including battery and printed parts |
| Battery location | Under the centre, positioned to balance the completed drone |
| Printed parts | Keep the combined mass around **3–4 g or less** |
At an 80 mm motor diagonal, adjacent motor centres are approximately **56.6 mm apart**. With 46 mm props, that leaves about **10.6 mm between neighbouring propeller discs before adding guards**. The complete propeller footprint will be roughly **103 × 103 mm**, so this is palm-sized—not an 80 mm-wide finished aircraft.
### Placement priorities
Put the **IMU near the centre**, with short SPI traces, away from the switching regulator and large motor-current paths. Put the ESP antenna at an appropriate board edge and follow Espressif’s full antenna keepout; do not tuck it under the battery or copper-filled frame. Keep the converter’s switching loops compact and follow TI’s grounding/layout guidance. ([Espressif Documentation][10])
### The extra 3D parts I would design
| Printed part | Proposed construction |
| --------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------- |
| **Four motor collars** | Lightweight split collars for the measured 7 mm motor bodies. A restrained TPU insert is an option; avoid soft mounts that let motors tilt. |
| **Four propeller guards** | Thin PA12 nylon guards. Start with approximately **50–52 mm internal diameter**, then check clearance under maximum flex. |
| **Battery saddle** | Underside holder for the measured pack, with rounded surfaces and retention that does not squeeze or puncture the pouch. |
| **Small canopy and landing nubs** | Minimal cover over the electronics, with antenna clearance and access to programming pads. |
Print a **motor-fit test piece first**, not the entire frame. A tight collar can damage the motor body; a loose one can change thrust direction.
**Buy moulded flight propellers. I would not use home-printed propellers on this build.**
---
## 5. How to make it responsive instead of “buffering”
### Use existing flight firmware as the starting point
I would start with **ESP-FC**, which lists ESP32-S3, ICM20602, brushed-motor outputs, ESP-NOW reception, and angle mode. It is compatible with Betaflight Configurator, but **it is not simply Betaflight firmware for an ESP board**. You still need the correct build, pin mapping, sensor orientation, motor ordering, and tuning. ([GitHub][4])
### Keep the stabilization loop onboard
Your transmitter should send **what you want the drone to do**. The onboard controller should continuously decide how to adjust the motors.
```text
Handheld transmitter → desired throttle / roll / pitch / yaw
Onboard:
IMU → attitude/rate estimate → controller → four motor outputs
```
My initial implementation targets would be a **500 Hz–1 kHz stabilization loop**, with a supported high-frequency brushed PWM setting, then measurements of timing, motor heating, and vibration before increasing rates. These are starting targets—not settings I have validated on this proposed PCB.
For control, I would use **a dedicated ESP-NOW transmitter**, not a browser page sending an accumulating queue of commands. ESP-FC documents an ESP-NOW receiver and a transmitter-module project; a custom two-gimbal handset still requires compatible transmitter firmware. Its ordinary Wi-Fi configuration mode is separate and does not allow arming while active. ([GitHub][11])
The implementation should always use the **newest valid command**, reject stale data, and have a tested loss-of-link failsafe. More filtering is not automatically better; tune filtering and controller gains against measured vibration rather than hiding a badly balanced motor with excessive smoothing.
### “Stable” does not automatically mean stationary hovering
A six-axis IMU helps control attitude. It does **not**, by itself, provide reliable position hold or automatic height hold. Espressif’s additional flight modes use additional sensing; optical flow and distance sensing would be a separate second-stage project. ([Espressif Systems][12])
For version one, I would target **predictable self-levelling flight with responsive manual control**.
---
## Before ordering the flight PCB
The most useful next test is **one selected motor + one selected propeller + the selected battery**, measuring thrust and current at representative battery voltages. Aim for roughly **2:1 combined maximum static thrust to actual all-up weight** as a design target, rather than a drone that barely lifts off.
Then verify the 3.3 V rail under radio and motor load. Before any free flight, test motor order, rotation, IMU axes, arming, and link-loss behaviour **with the propellers removed**. An external **4.2 V 1S LiPo charger with suitable adjustable current** is also needed; its exact model remains unselected until the battery’s permitted charge current and connector are confirmed.
**My recommendation is this S3 + SPI ICM-20602 + 716/46 mm platform. The main electronics are selected, but I would not call the complete build “ready to manufacture” until the motor-pack ambiguity, regulator inductor, remaining passive stock, schematic review, and thrust test are resolved.**
The [workbook](sandbox:/mnt/data/Tiny_ESP_Drone_Component_Plan.xlsx) separates those unresolved items from the selected parts across four sheets: **core JLC BOM, PCB support, motors/accessories, and build/3D checks**.
[1]: https://docs.espressif.com/projects/espressif-esp-drone/en/latest/hardware.html "Hardware Reference — ESP-Drone documentation"
[2]: https://jlcpcb.com/partdetail/EspressifSystems-ESP32_S3_MINI_1N8/C2913206?utm_source=chatgpt.com "ESP32-S3-MINI-1-N8 | Espressif Systems - JLCPCB"
[3]: https://jlcpcb.com/partdetail/EspressifSystems-ESP32_S3_MINI_1N8/C2913206 "ESP32-S3-MINI-1-N8 | Espressif Systems | JLCPCB"
[4]: https://github.com/rtlopez/esp-fc "GitHub - rtlopez/esp-fc: Flight controller software for hobbyist - build your own flight controller. · GitHub"
[5]: https://www.aosmd.com/sites/default/files/res/datasheets/AO3400A.pdf "https://www.aosmd.com/sites/default/files/res/datasheets/AO3400A.pdf"
[6]: https://ifuturetech.org/product/716-3-7v-micro-coreless-motor/ "https://ifuturetech.org/product/716-3-7v-micro-coreless-motor/"
[7]: https://quartzcomponents.com/products/3-7v-30c-400mah-lithium-polymer-lipo-battery-yy702030?srsltid=AfmBOoqkFMMkyHqjd6un7s3Ryk4hlYQRaNK6XOESmH--RiCSNJXdjM2F "https://quartzcomponents.com/products/3-7v-30c-400mah-lithium-polymer-lipo-battery-yy702030?srsltid=AfmBOoqkFMMkyHqjd6un7s3Ryk4hlYQRaNK6XOESmH--RiCSNJXdjM2F"
[8]: https://www.ti.com/lit/ds/symlink/tps63030.pdf "https://www.ti.com/lit/ds/symlink/tps63030.pdf"
[9]: https://jlcpcb.com/partdetail/0603WAF1000T5E/C22775 "https://jlcpcb.com/partdetail/0603WAF1000T5E/C22775"
[10]: https://documentation.espressif.com/esp32-s3-mini-1_mini-1u_datasheet_en.html "https://documentation.espressif.com/esp32-s3-mini-1_mini-1u_datasheet_en.html"
[11]: https://github.com/rtlopez/esp-fc/blob/master/docs/wireless.md "https://github.com/rtlopez/esp-fc/blob/master/docs/wireless.md"
[12]: https://docs.espressif.com/projects/espressif-esp-drone/en/latest/gettingstarted.html?utm_source=chatgpt.com "Get Started — ESP-Drone documentation - Espressif Systems"