Define the board's job and its limits before any part.
This board's requirements are short and clear: power it from one USB-C port, run an ESP32-S3, bring its pins out to headers, and don't hurt the radio. Nail these down now and the rest of the build is mostly careful bookkeeping.
Read this one. Nothing to build yet: you are settling the four promises the rest of the lesson has to keep.
You won't hunt for a part or draw a single symbol. The you download at the schematic stage ships with every part's symbol, footprint, and 3D model already placed, and the , manufacturer part numbers and all, is specified for you. Later, if you'd rather not risk your own layout, you can even order from the verified reference files. You bring the bench (below); we bring the parts library.
This board is hand-built with a small setup, anchored by a temperature-controlled iron: every joint, the module and USB-C connector included, was chosen to be iron-solderable. Beyond the iron you'll want flux, tweezers, a multimeter, and some magnification for inspecting joints. A hot-air station is optional; ASSEMBLY shows both paths. Missing any of the essentials? Sort that out before you order parts.
Either works on this board. We recommend lead-free () for two honest reasons: no lead to handle or dispose of, and it's the real commercial process. Your joints behave like production. The catch: lead-free melts ~35 °C hotter and its joints look duller, so leaded (63/37) is more forgiving for a first board. If you go leaded, don't eat at the bench and wash your hands. (Corrosion and tin whiskers aren't a real worry either way on a board like this.)
▸ The bench · tick what you own
The gear you'll need, grouped by how essential it is. Pick what you're missing. The iron is the anchor; a 2-in-1 heat station covers the optional hot-air path too, and the WEP combo bundles several of the smaller items. Tiered rows give you a budget / mid / pro choice.
Required
0/7
The iron is the required tool: every joint here is iron-solderable. The WEP 2-in-1 adds hot air for the optional path and bundles solder, tips, nozzles, tweezers and a desoldering pump.
Rosin-core, lead-free. 0.6 mm for fine SMD, 0.8 mm for the bigger joints. (The WEP combo also includes a starter spool.)
Liquid no-clean RMA flux in a dropper, ideal for drag-soldering.
A precision anti-static set. (The WEP combo also includes a pair.)
A USB scope for inspecting joints and hunting solder bridges. (Short working distance: it's for inspecting, not soldering under.)
Needs a beeper and DC volts; auto-ranging is nicer.
A known-good DATA cable, not charge-only. USB-C-to-USB-C shown. Grab a USB-A-to-C instead if your computer has the older port.
Recommended
0/5
Adjustable, with a grounding cord + alligator clip.
Flux-coated desoldering braid for lifting bridges.
The coiled-brass kind, plus tip tinner to revive a dead tip.
99% IPA, plus a cheap acid/flux brush to wash residue.
Clear the flux fumes, a safety item.
Helpful
0/5
Only for the optional hot-air path: SAC305 no-clean syringe, ~217 °C. A 15 g syringe is plenty; a T3/T4 mesh suits 0805/0402. Skip pricier T5 (that's for fine-pitch BGA).
900M-style tips that fit the WEP and Hakko-compatible irons, handy to have spares.
Magnetic, anti-static, with a grounding cord: a safe surface that catches parts.
Reads volts + amps; handy at bring-up.
5–10 mm polyimide tape to hold parts during reflow.
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A USB-C-powered ESP32-S3 breakout: a small, hand-solderable board that brings the module's pins out to breadboard headers.
At the center is U1, the ESP32-S3-WROOM-1, a module (a tiny computer on a single chip) with Wi-Fi and Bluetooth already built in. One USB-C port (J1) does two jobs at once: it powers the board and it loads your programs. The S3 can speak USB by itself, so it shows up on your computer and takes firmware directly. There's no separate USB-to-serial 'programmer' chip in the middle. Two snap-apart headers (J2/J3) bring the pins out to a breadboard. That's the whole mission: a clean, reliable way to get your hands on the S3.
| Ref | Part | Role |
|---|---|---|
| U1 | ESP32-S3-WROOM-1-N16R2 | The microcontroller module (native USB) |
| J1 | USB4110-GF-A | USB-C receptacle: power in + native-USB programming |
| F1 | 1206L050YR | Resettable fuse: trips if something shorts, then heals itself |
| D1 | USBLC6-2SC6 | ESD protector: soaks up static zaps at the connector before they reach the chip |
| U2 | RT9080-33GJ5 |
Will the 3.3 V rail hold up when Wi-Fi transmits? Answer that now, on paper. It's a five-minute sum.
USB hands you 5 V. The (a kind of voltage regulator, U2) turns that into the 3.3 V the chip needs, at up to 600 mA. The ESP32-S3 sips current most of the time, but it gulps hard for a few milliseconds every time its radio transmits. Add up the worst case, that gulp plus everything else on the board, and check that it fits under 600 mA. Here it just barely does: roughly 50 mA of headroom. That is exactly why the board uses a 600 mA regulator and a 10 µF (C1) instead of a tiny 150 mA part. Hang hungry loads (a motor, a servo) off the rail later and you invite a : the voltage sagging low enough to reset the chip.
On any Wi-Fi-connected ESP32, half the analog pins go dark.
Here's a rule that's easy to honor now and maddening to discover later: can't be used while the radio is active, and on a Wi-Fi board, the radio is basically always active. So every analog input you plan to read has to land on an pin. Decide this now, while you're choosing which pin does what, not at bring-up, when an analog reading comes back as garbage but only when Wi-Fi is on.
The last promise from the top of this card: the module's antenna needs empty space. You'll enforce it at layout, but it's a requirement now: it decides the board's shape and where U1 sits.
The striped end of U1 is the Wi-Fi antenna. Metal near an antenna detunes it: the radio still 'works,' but its range quietly collapses. So this board promises the antenna clear air: the module sits at the board edge with the antenna end hanging past it, and nothing copper (no traces, no ) goes under or beside that zone. Today it's just a line in your note; at layout it becomes a drawn keep-out.
Four short lines, in your own words. Nothing uploads and no gate waits on it, which is exactly why it is worth doing.
Open a plain text file (or a notebook page) and write the board's promises in your own words, one short line each. Keep this note where you can see it while you build. Nothing gets uploaded and no gate is waiting on it, so it is easy to skip. Do the writing anyway: putting each promise in your own words instead of copying it is what makes it stick, and writing it by hand helps more still (Mueller and Oppenheimer, 2014). These four lines are the promises the rest of the lesson keeps. Reference: Mueller and Oppenheimer, "The Pen Is Mightier Than the Keyboard," Psychological Science, 2014.
Checkpoint
Quick check: requirements
1/8
You've pinned down what this board has to do: powered and programmed over one USB-C port, a 3.3 V budget that survives a Wi-Fi burst, the ADC1-only rule, and clear air for the antenna. The quick check above is the gate. Pass it and the next stage opens. There's nothing to attach on a build this size: no requirements note, no design-review checklist.
Next · BOM SOURCING
drag to rotate
| C1 | 10 µF bulk cap | Local reservoir that covers the Wi-Fi current spikes |
| J2, J3 | 1×22 headers | Break the GPIO out to a breadboard |
Check yourself
Why does this board need no separate USB-to-serial programmer chip?
Most older microcontrollers can't speak USB at all. They talk a simpler language called serial, so the board needs a little translator chip, something like a CP2102 or CH340, sitting between the USB port and the chip just to load code. The ESP32-S3 has a USB controller built right into the silicon, so the USB-C port wires almost straight to the module. That's one fewer chip to buy, place, and solder, and you get a few things for free: the same port can act as a serial console and even a hardware debugger. The one tradeoff is that if your own program ever locks up the USB peripheral, you fall back on the BOOT and EN buttons to force the chip into download mode by hand. That's exactly why the board carries two buttons (you'll wire them on the schematic).
Check yourself
The regulator can supply up to 600 mA. The ESP32 mostly sips current but gulps hard for a few milliseconds each time its radio transmits. What rides out those gulps so the rail doesn't dip?
Add up the worst case. The ESP32-S3 can peak near 500 mA during a Wi-Fi transmit burst, and the rest of the board (LEDs, the regulator's own draw, anything you hang off the headers) is maybe 50 mA. That's about 550 mA against the 's 600 mA ceiling. That leaves roughly 50 mA of headroom, thin on paper, but fine here: nothing else on this board is hungry, and the bursts are brief. It's exactly why the design picks a 600 mA part; a tiny 150 mA regulator would the instant Wi-Fi keyed up. The transmit spikes are also far faster than the regulator can react to, so C1, the 10 µF , holds a local pool of charge to cover them while the regulator catches up. Hang a motor or a servo on the rail and you blow the budget. Those want their own supply.
✓ ADC1 GPIO 1-10
✗ ADC2 GPIO 11-20
Wi-Fi borrows ADC2's converter, so these read garbage while the radio is on.
Check yourself
You wire a knob to an ADC2 pin and the reading is garbage only when Wi-Fi is on. What rule did you break?
The ESP32-S3 has two analog-to-digital converters, and . The Wi-Fi radio borrows ADC2's hardware while it's running, so a program that reads an ADC2 pin with Wi-Fi active gets an error or a meaningless number, and because this is a Wi-Fi board, the radio is essentially always on. The fix is a planning decision, not a code workaround: route anything you'll read as analog to an ADC1 pin (on the S3 those are GPIO1 through GPIO10). Settle it here, while the pins are still just names on a list, and you'll never hit the 'works until I connect to Wi-Fi' bug at bring-up.
UNDER THE ANTENNA
The ground pour (hatch) fills the rest, under the U1 body and pads.