Heltec Wireless Shell (V3)
Solder-down ESP32-S3 + SX1262 LoRa module with 1.27 mm castellated pads and two IPEX sockets - no USB, charger or buttons.
Heltec Wireless Shell (V3) Pinout
49 pins · 1.27 mm pitch
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | - | VeVext | power | - | pad 1: Vext, a 3.3 V output switched by GPIO36 (LOW = on) |
| 2 | - | VeVext | power | - | pad 2: Vext |
| 3 | - | 3V3 | power | - | pad 3: the module supply input, 2.7-3.5 V |
| 4 | - | 3V3 | power | - | pad 4: supply input |
| 5 | 33 | GPIO33 | safe | pwm | pad 5 |
| 6 | 34 | GPIO34 | safe | pwm | pad 6 |
| 7 | 35 | GPIO35 | safe | pwm | pad 7. The arduino-esp32 variant calls it LED_BUILTIN, but the module has no LED on it |
| 8 | 36 | GPIO36Vext_Ctrl | safe | pwm | pad 8: switches the Vext pads - LOW = on |
| 9 | 37 | GPIO37 | safe | pwm | pad 9 |
| 10 | 38 | GPIO38 | safe | pwm | pad 10 |
| 11 | 39 | GPIO39 | strapping | pwm | pad 11 |
| 12 | 40 | GPIO40 | strapping | pwm | pad 12 |
| 13 | 41 | GPIO41 | strapping | pwm | pad 13 |
| 14 | 42 | GPIO42 | strapping | pwm | pad 14 |
| 15 | 44 | GPIO44RXDU0RXD | uart | uart · pwm | pad 15: UART0 RX - the programming port, via an external USB-serial bridge |
| 16 | 43 | GPIO43TXDU0TXD | uart | uart · pwm | pad 16: UART0 TX - the programming port |
| 17 | 45 | GPIO45 | strapping | pwm | pad 17 |
| 18 | 46 | GPIO46 | strapping | pwm | pad 18 |
| 19 | - | ANT_2.4G | control | - | pad 19: the 2.4 GHz RF signal, for an antenna on your own board |
| 20 | 1 | GPIO1 | safe | adc · touch · pwm | pad 20 |
| 21 | 2 | GPIO2 | safe | adc · touch · pwm | pad 21 (Heltec's pin map mislabels it 20) |
| 22 | 3 | GPIO3 | strapping | adc · touch · pwm | pad 22 |
| 23 | - | RSTEN | control | - | pad 23: chip reset (CHIP_PU) |
| 24 | 6 | GPIO6 | safe | adc · touch · pwm | pad 24 |
| 25 | 7 | GPIO7 | safe | adc · touch · pwm | pad 25 |
| 26 | 15 | GPIO15 | safe | adc · pwm | pad 26 |
| 27 | 16 | GPIO16 | safe | adc · pwm | pad 27 |
| 28 | 18 | GPIO18 | safe | adc · pwm | pad 28 |
| 29 | 20 | GPIO20USB_D+ | uart | adc · pwm | pad 29: native USB D+ |
| 30 | 26 | GPIO26 | safe | pwm | pad 30 |
| 31 | 17 | GPIO17 | safe | adc · pwm | pad 31 |
| 32 | 19 | GPIO19USB_D- | uart | adc · pwm | pad 32: native USB D- |
| 33 | 21 | GPIO21 | safe | pwm | pad 33 |
| 34 | 0 | GPIO0BOOT | strapping | pwm | pad 34: strapping pin - hold LOW at reset for download mode |
| 35 | 5 | GPIO5 | safe | adc · touch · pwm | pad 35 |
| 36 | 4 | GPIO4 | safe | adc · touch · pwm | pad 36 |
| 37 | 48 | GPIO48 | strapping | pwm | pad 37 |
| 38 | 47 | GPIO47 | strapping | pwm | pad 38 |
| 39 | 14 | GPIO14LoRa_DIO1 | strapping | adc · touch · pwm | pad 39: SX1262 DIO1 interrupt (the arduino-esp32 variant calls it DIO0). It is ALSO on the header, so do not use it for anything else while the radio is in use |
| 40 | 13 | GPIO13LoRa_BUSY | strapping | adc · touch · pwm | pad 40: SX1262 BUSY. It is ALSO on the header, so do not use it for anything else while the radio is in use |
| 41 | - | GND | ground | - | pad 41 |
| 42 | - | GND | ground | - | pad 42 |
| 43 | - | GND | ground | - | pad 43 |
| 44 | - | GND | ground | - | pad 44 |
| 45 | 8 | GPIO8LoRa_NSS | safe | adc · touch · pwm | SX1262 chip select |
| 46 | 9 | GPIO9LoRa_SCK | strapping | adc · touch · pwm | SX1262 SPI clock |
| 47 | 10 | GPIO10LoRa_MOSI | strapping | adc · touch · pwm | SX1262 SPI MOSI |
| 48 | 11 | GPIO11LoRa_MISO | strapping | adc · touch · pwm | SX1262 SPI MISO |
| 49 | 12 | GPIO12LoRa_RST | strapping | adc · touch · pwm | SX1262 reset |
Start with these
17 pins with no boot or system involvementFreely assignable - no strapping, flash, USB or JTAG duties. Ideal first picks for buttons, sensors and LEDs.
Fine - with a little care
13 pins · 12 things to knowGPIO36 pad 8: switches the Vext pads - LOW = on onboard hardware
Wired to the Vext power switch on this board. The pin is yours if you give that up, but nothing else can share it.
GPIO39 JTAG test clock (MTCK); IO MUX alternates CLK_OUT3 and SUBSPICS1 (chip select on the alternative SUBSPI memory bus, unused on standard modules) JTAG
Default JTAG TCK - keep it free if you debug over JTAG. It is not a flash or PSRAM line on standard modules: those sit on GPIO26-37.
GPIO40 JTAG test data out pin (MTDO) JTAG
Default JTAG TDO output for debugging. Using it as GPIO will interfere with JTAG debugging functionality.
GPIO41 JTAG test data in pin (MTDI) JTAG
Default JTAG TDI input for debugging. Should be reserved for JTAG or left unused if JTAG is to remain available.
GPIO42 JTAG test mode select pin (MTMS) JTAG
Default JTAG TMS signal for debugging. Using this pin for other purposes will disable the JTAG interface (unless JTAG is rerouted to USB).
GPIO44 UART0 receive pin (U0RXD), default serial console RX UART
Used for bootloader input (download mode via serial). If repurposed, you cannot use the default UART0 download mode for programming the chip.
GPIO43 UART0 transmit pin (U0TXD), default serial console TX UART
Used for bootloader output and UART console logs. If repurposed, you will lose the default serial output (and programming via UART0).
GPIO45 Bootstrapping pin (selects VDD_SPI flash voltage) Strapping
Determines flash/PSRAM power voltage (3.3 V vs 1.8 V) at boot. Must match hardware configuration; using as GPIO can upset flash supply setting.
GPIO46 Bootstrapping pin (used with GPIO0 for boot mode; controls ROM log output) Strapping
Must be at a defined level during reset (with GPIO0) to select normal or download boot and UART/USB print mode. This pin is input-only (no output drive), so it should be left for its intended strapping function.
GPIO3 Bootstrapping pin (controls JTAG signal source) Strapping
Sampled at reset to select JTAG interface (USB Serial/JTAG controller vs. external pins). Improper use can disable external JTAG or alter debug interface.
GPIO0 Bootstrapping pin (Chip boot mode selection) Strapping
Must be pulled high (default) or low (to enter UART download mode) at reset. Using it for other functions can interfere with boot mode configuration.
GPIO48GPIO47 Octal SPI differential clock legs (SPICLK_P/N_DIFF), used only by the 1.8 V octal flash/PSRAM variants Other
Only the 1.8 V octal parts (ESP32-S3R8V, ESP32-S3R16V) run the differential memory clock here, and on those the pin works at 1.8 V instead of 3.3 V. On the common 3.3 V modules it is a normal GPIO - several devkits drive their RGB LED from GPIO48.
- GPIO48Octal SPI differential clock negative leg (SPICLK_N_DIFF), used only by the 1.8 V octal flash/PSRAM variants
- GPIO47Octal SPI differential clock positive leg (SPICLK_P_DIFF), used only by the 1.8 V octal flash/PSRAM variants
Only if you know the tricks
9 pins · 2 things to knowGPIO20GPIO19 USB OTG differential data pair (D- and D+) USB
By default connected to the on-chip USB Serial/JTAG controller. Using it as general GPIO without reconfiguring IO MUX will interfere with USB functionality.
- GPIO20USB OTG positive differential data line (USB_D+)
- GPIO19USB OTG negative differential data line (USB_D-)
GPIO14GPIO13GPIO8GPIO9GPIO10GPIO11GPIO12 Used by the SX1262 LoRa radio onboard hardware
Wired to the SX1262 LoRa radio on this board, which is soldered down. Driving it from your own code breaks that function.
- GPIO14pad 39: SX1262 DIO1 interrupt (the arduino-esp32 variant calls it DIO0). It is ALSO on the header, so do not use it for anything else while the radio is in use
- GPIO13pad 40: SX1262 BUSY. It is ALSO on the header, so do not use it for anything else while the radio is in use
- GPIO8SX1262 chip select
- GPIO9SX1262 SPI clock
- GPIO10SX1262 SPI MOSI
- GPIO11SX1262 SPI MISO
- GPIO12SX1262 reset
Across 49 pins (1.27 mm pitch), the Heltec Wireless Shell (V3) exposes 39 GPIO plus Ve, 3V3 and GND for power.
Beyond plain digital I/O you get 20 ADC-capable pins for sensors and battery monitoring, PWM on every GPIO and 14 capacitive-touch inputs.
13 of the exposed pins carry boot-time or system duties on the ESP32-S3 (GPIO36, GPIO39, GPIO40 and 10 more) - check the guidance above before wiring anything to them. GPIO33, GPIO34, GPIO35, GPIO37 and 13 more are free of any such role - the safest first picks.
Getting started
flash your first firmware in ~2 minutesBoard: Heltec Wireless Shell (V3) Flash Size: 8MB (64Mb) Flash Mode: DIO Partition Scheme: 8M with spiffs (3MB APP/1.5MB SPIFFS) Upload Speed: 921600
// toggle GPIO33 - wire an LED and resistor to it
void setup() {
pinMode(33, OUTPUT);
}
void loop() {
digitalWrite(33, HIGH); delay(500);
digitalWrite(33, LOW); delay(500);
}[env:heltec_wireless_shell_V3]
platform = espressif32
board = esp32-s3-devkitc-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600esp32-s3-devkitc-1 - or type it after board =.esp32:
board: esp32-s3-devkitc-1
variant: esp32s3
framework:
type: esp-idf
# blink - GPIO33
output:
- platform: gpio
pin: 33
id: led_out
light:
- platform: binary
name: "LED"
output: led_outesp32-s3-devkitc-1 (same ids as PlatformIO).esptool.py --chip esp32s3 --port /dev/ttyACM0 \
--baud 921600 write_flash 0x0 firmware.bin--port = your /dev/tty* (macOS/Linux) or COMx (Windows).Downloads
Free for non-commercial use, credit espboards.dev · License
Board illustration
The bare Heltec Wireless Shell (V3) board drawn to scale at 38.4 × 16.1 mm, with no pin labels on it. Made for slide decks, wiring diagrams and project write-ups where a photo is too busy. Take the scalable SVG for print or editing, the high-resolution PNG to drop straight in, or the transparent PNG when you need it with no background behind it.
Pinout diagram
Every pin on both sides of the board with its functions, drawn by ESPboards from the ESP32-S3 Series Datasheet v2.2 - the same sheet shown at the top of this page. The PNG is a high-resolution image for screens, the SVG is vector so it stays sharp at any size, and the PDF is laid out to print on A4 or Letter.
Yours to use, share and adapt for non-commercial work, as long as you credit espboards.dev - the full terms and ready-made credit lines are here.
Specifications
ESP32-S3 · 38.4 × 16.1 mm · vs other ESP32 chips →Dimensions
About this board
Inside sits the ESP32-S3 - a dual-core Xtensa with vector extensions suited to AI workloads.
At $11.90 it's cheaper than most ESP32-S3 boards, which usually run around $29.
With 39 GPIO broken out, you get more pins to play with than most ESP32-S3 boards offer.
Around the module: LoRa (SX1262).
- A MODULE, not a dev board: 44 castellated pads at 1.27 mm to solder onto your own PCB, under a metal shield
- No USB connector - program it over UART0 (pads 15 / 16) with an external USB-serial bridge, or wire the native USB pads (GPIO19 / GPIO20) to a connector; Heltec publishes a reference carrier design
- Two IPEX 1.0 (u.FL) sockets, one for LoRa and one for 2.4 GHz; the 2.4 GHz signal is also on pad 19
- Sold as HTIT-Wsh-HF (863-928 MHz) and HTIT-Wsh-LF (470-510 MHz)
- LoRa BUSY (GPIO13) and DIO1 (GPIO14) are brought out on pads 40 and 39
- Vext pads (1-2) are a 3.3 V output switched by GPIO36, LOW = on
- The module has no LED: the arduino-esp32 variant says LED_BUILTIN 35, but Heltec's reference carrier puts its LED on GPIO18
- No PSRAM - the ESP32-S3FN8 has 8 MB of in-package flash only
Where to buy
prices are typical street pricesResources
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