ESP32-S3-WROOM-1 PCB Design Guide: Footprint, Pinout, and Alternatives
Dual-core Wi-Fi 4 + Bluetooth 5 (LE) MCU module with Xtensa LX7 at 240 MHz, up to 16 MB flash and 16 MB PSRAM, USB OTG, and vector instructions for DSP and neural-network workloads.
The ESP32-S3-WROOM-1 is Espressif's current-generation Wi-Fi + Bluetooth LE MCU module, built around the ESP32-S3 SoC. It combines a dual-core Xtensa LX7 CPU at up to 240 MHz, 512 KB of on-chip SRAM, up to 16 MB of external Quad SPI flash, and up to 16 MB of Octal or Quad SPI PSRAM into a 18.0 x 25.5 mm castellated module with an on-board PCB antenna. The SoC adds vector instruction extensions that accelerate neural-network inference and DSP workloads, a full-speed USB 2.0 OTG interface, and a USB Serial/JTAG controller that eliminates the need for an external USB-UART bridge during development.
This module is not a drop-in successor to the ESP32-WROOM-32. The footprint and pinout differ, the strapping-pin scheme changed, and the S3 adds USB OTG and vector instructions. Choose the exact module from its required radio features, memory variant, exposed GPIOs, antenna arrangement, and temperature grade rather than treating WROOM-family modules as footprint-compatible.
The mistakes that keep an S3 board from booting are well-understood: copper under the PCB antenna, mis-strapped boot pins, an undersized 3.3 V rail that browns out during a TX burst, ordering the WROOM-1U when the layout expects the PCB antenna of the WROOM-1, and assigning GPIO35-37 on Octal PSRAM variants that have them dedicated to the PSRAM interface. Each is covered below.
What breaks boards
Antenna keep-out: no copper under or around the PCB antenna end of the module
The on-board PCB antenna occupies one end of the 25.5 mm module length. Espressif requires no copper traces, ground pours, or metal components under or beside the antenna area. The module should be placed at the board edge with the antenna overhanging. Copper under the antenna detunes it and can reduce range dramatically. This is the single most common WROOM-1 layout mistake and it applies only to the WROOM-1 (PCB antenna) variant, not the WROOM-1U. See ESP32-S3 Hardware Design Guidelines, General Principles of PCB Layout for Modules.
Strapping pins control boot mode and flash voltage at reset. Get them wrong and the module will not boot
GPIO0 and GPIO46 determine SPI Boot vs Download Boot mode at reset. GPIO45 controls VDD_SPI voltage (3.3 V default): if pulled high, VDD_SPI switches to 1.8 V via the internal flash regulator, which will prevent a 3.3 V flash from responding. GPIO3 selects between USB Serial/JTAG and physical JTAG pins. All strapping pins are sampled at the rising edge of EN and require a 3 ms hold time after EN goes high. Do not connect heavy loads or strong pull-downs to strapping pins without understanding the boot consequences. The default configuration is GPIO0 weak pull-up, GPIO45 weak pull-down, GPIO46 weak pull-down.
The 3.3 V rail needs the datasheet's 0.5 A minimum supply capability, plus margin for the rest of the board
TX current peaks at 355 mA for 802.11b at full power (Table 6-4), and Espressif recommends at least 0.5 A of external supply capability (Table 6-2). Size the regulator and local decoupling for the selected module variant, attached loads, and transient response. Section 9 shows 10 uF and 0.1 uF close to 3V3 and recommends an EN delay network of 10 kOhm and 1 uF so the supply can stabilize before startup.
WROOM-1 and WROOM-1U are different modules with different footprints and certifications. Do not cross them on a BOM
ESP32-S3-WROOM-1 has a PCB antenna and measures 18.0 x 25.5 x 3.1 mm. ESP32-S3-WROOM-1U has an external antenna connector (U.FL / MHF I / AMC compatible) and measures 18.0 x 19.2 x 3.2 mm. The WROOM-1U antenna keep-out zone is replaced by a connector footprint and microstrip routing. RF certifications differ between the two. The series comparison tables (1-1 and 1-2) show identical electrical specs across all flash/PSRAM variants, but the physical module is not interchangeable. When a BOM says ESP32-S3-WROOM-1, verify that the PCB antenna variant and not the 1U is what the layout expects.
Octal PSRAM variants steal GPIO35-37; N16R16VA runs GPIO47-48 at 1.8 V
Modules with Octal SPI PSRAM (R8 and R16V suffixes, e.g. ESP32-S3-WROOM-1-N8R8) dedicate GPIO35, GPIO36, and GPIO37 to the Octal SPI PSRAM interface. These pins are not available for general-purpose I/O on those variants. On the N16R16VA variant, VDD_SPI is 1.8 V (not 3.3 V), which means GPIO47 and GPIO48 also operate at 1.8 V logic levels. Check your variant's PSRAM type when assigning pin functions: Quad SPI PSRAM variants (R2 suffixes) do not consume GPIO35-37 and run all GPIOs at 3.3 V. The datasheet pin description table (3-1) calls this out in footnotes b and c.
Key specifications
| Parameter | Value | Source |
|---|---|---|
| SoC | ESP32-S3, Xtensa dual-core 32-bit LX7, up to 240 MHz | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Section 1.1 Features, CPU and On-Chip Memory |
| SRAM | 512 KB SRAM, 16 KB SRAM in RTC | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Section 1.1 Features, CPU and On-Chip Memory |
| Flash | Up to 16 MB Quad SPI (default max clock 80 MHz) | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Section 1.1 Features, Table 1-1, Table 6-8 |
| PSRAM | Up to 16 MB Octal SPI (variant-dependent; max clock 80 MHz) | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Table 1-1, Table 6-9 |
| Wi-Fi | 802.11b/g/n, 2412-2484 MHz, on-board PCB antenna | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Sections 1.1 and 7.1 |
| Bluetooth | Bluetooth 5 (LE), Bluetooth mesh, 2402-2480 MHz | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Sections 1.1 and 7.2 |
| VDD33 (supply voltage) | 3.0 to 3.6 V (recommended); absolute max -0.3 to 3.6 V | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Tables 6-1 and 6-2 |
| IVDD (external supply current) | 0.5 A minimum recommended | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Table 6-2, IVDD row |
| TX current (Wi-Fi 802.11b 1 Mbps @20.5 dBm) | 355 mA peak | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Table 6-4 |
| RX current (Wi-Fi 802.11b/g/n HT20) | 95 mA | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Table 6-4 |
| Deep-sleep current (RTC memory only) | 7 uA | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Table 6-7 |
| Light-sleep current | 240 uA (VDD_SPI and Wi-Fi powered down, all GPIOs high-impedance) | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Table 6-7 |
| Operating ambient temperature | -40 to 85 degC (standard); -40 to 65 degC (R8/R16V); -40 to 105 degC (H4) | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Table 1-1, Table 6-2 |
| Module dimensions | 18.0 x 25.5 x 3.1 mm | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Table 1-1, Section 10.1 |
| TX power (802.11b 1 Mbps) | 20.5 dBm typical | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Table 7-2 |
| RX sensitivity (802.11b 1 Mbps) | -98.2 dBm typical | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Table 7-4 |
| GPIO count | Up to 36 GPIOs (41 pins total) | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Section 1.1 Features, Section 3.2 Pin Description |
| Flash endurance / data retention | 100,000 program/erase cycles; 20-year data retention | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Table 6-8 |
| ESD | HBM +/-2000 V, CDM +/-500 V | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Section 12.2 |
| Reflow profile | Peak 235-250 degC, SAC305 lead-free; MSL 3 | ESP32-S3-WROOM-1 & WROOM-1U Datasheet v1.8, Sections 12.1 and 12.3 |
Verified against the manufacturer datasheet on 2026-07-12. Confirm the current revision before production use.
Alternatives
- ESP32-S3-MINI-1: Smaller form factor (15.8 x 20.3 mm) SMD module with PCB antenna, same ESP32-S3 SoC and Wi-Fi/BLE stack. Fewer GPIOs exposed. Use when board area is tight and the WROOM-1 pinout requires more I/O than needed. Datasheet covers ESP32-S3-MINI-1 & MINI-1U.
- ESP32-S3-WROOM-2: Larger module (31.4 x 18.0 mm) with IPEX antenna connector, up to 32 MB Octal SPI flash. Different footprint. Use when external antenna and higher flash density are required. Separate datasheet from the WROOM-1 family.
- ESP32-C3-WROOM-02: RISC-V single-core alternative with Wi-Fi 4 + BLE 5. Lower cost, lower active and sleep current, but single-core and no USB OTG or vector instruction extensions. Good choice for simple sensor nodes that do not need dual-core or AI acceleration.
- ESP32-WROOM-32E: Previous-generation Wi-Fi + BT/BLE module (dual-core Xtensa LX6, no USB OTG, no vector instructions). Active and footprint-compatible with original WROOM-32 but completely different footprint from WROOM-1. Use for existing WROOM-32 designs that do not need S3 features.
Common questions
- ESP32-S3-WROOM-1 vs ESP32-WROOM-32: which one should I use for a new design?
- The S3-WROOM-1 adds vector instructions, USB OTG, USB Serial/JTAG, Bluetooth 5 LE, and more memory variants, but it uses a different footprint and does not support Bluetooth Classic. Use the exact module whose radio, memory, USB, GPIO, antenna, and temperature requirements match the board; do not treat it as a drop-in WROOM-32 replacement.
- How do I pick the right flash/PSRAM variant?
- The ordering suffix encodes it: N4 = 4 MB flash, no PSRAM; N8R2 = 8 MB flash + 2 MB Quad SPI PSRAM; N16R8 = 16 MB flash + 8 MB Octal SPI PSRAM; H4 = 4 MB flash, no PSRAM, high-temperature (-40 to 105 degC). Quad SPI PSRAM (R2) keeps GPIO35-37 free. Octal SPI PSRAM (R8, R16V) trades three GPIOs for higher PSRAM bandwidth. The N16R16VA variant runs VDD_SPI at 1.8 V. Choose flash size based on firmware + filesystem needs; choose PSRAM if your application allocates large buffers for camera, display, or ML model tensors.
- Can I use the ESP32-S3-WROOM-1 without an external USB-UART chip?
- Yes. The S3 has a built-in USB Serial/JTAG controller accessible via GPIO19 (USB D-) and GPIO20 (USB D+). Connect these directly to a USB connector with 27-ohm series resistors and the chip appears as a CDC-ACM serial port plus a JTAG debug interface. No CP2102 or CH340 needed. This is one of the biggest workflow improvements over the original ESP32.
- What is the antenna keep-out zone, exactly?
- The PCB antenna occupies roughly the last 8 mm of the 25.5 mm module length on the end opposite the GND/3V3 pins. No copper, ground pours, traces, or metal components on any layer of the base board under or beside the antenna area. Place the module at the board edge with the antenna overhanging the edge if possible. The exact dimensions are in the ESP32-S3-Hardware-Design-Guidelines, Section General Principles of PCB Layout for Modules. This applies only to the WROOM-1 (PCB antenna); the WROOM-1U has a connector instead and requires 50-ohm microstrip routing.
- Does the ESP32-S3-WROOM-1 support Bluetooth Classic?
- No. The ESP32-S3 supports Bluetooth 5 LE and Bluetooth mesh only. There is no BR/EDR (Bluetooth Classic) radio on the S3. If you need Classic (A2DP audio, SPP serial), use the original ESP32 (ESP32-WROOM-32E) or an ESP32-C6 plus an external Classic radio. The original ESP32 is the only Espressif chip with BR/EDR as of this writing.
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