Crabik Slot ESP32-S3
A modular ESP32-S3 development board designed for slot-based expansion and customization.
Crabik Slot ESP32-S3 Pinout
42 pins · 2.54 mm pitch
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 0 | BOOT_BTN | strapping | - | |
| 2 | 1 | S1T1PWM | safe | touch | |
| 3 | 2 | S3T2PWM | safe | touch | |
| 4 | 3 | S7T3PWM | strapping | touch | |
| 5 | 4 | S8T4PWM | safe | touch | |
| 6 | 5 | S9T5PWM | safe | touch | |
| 7 | 6 | S10T6PWM | safe | touch | |
| 8 | 7 | S11T7PWM | safe | touch | |
| 9 | 8 | S12T8PWM | safe | touch | |
| 10 | 9 | S13T9PWM | strapping | touch | |
| 11 | 10 | S14T10PWM | strapping | touch | |
| 12 | 11 | S4T11PWM | strapping | touch | |
| 13 | 12 | S2T12PWM | strapping | touch | |
| 14 | 13 | SDAPWM | strapping | i2c | |
| 15 | 14 | SCLPWM | strapping | i2c | |
| 16 | 15 | EN_TROYKAPWM | safe | - | |
| 17 | 16 | LIPO_ALERTPWM | safe | - | |
| 18 | 17 | S5PWM | safe | - | |
| 19 | 18 | S6PWM | safe | - | |
| 20 | 19 | USB_DNPWM | uart | - | |
| 21 | 20 | USB_DPPWM | uart | - | |
| 22 | 21 | LED_BUILTINPWM | safe | - | |
| 23 | 33 | S19PWM | safe | - | |
| 24 | 34 | S20PWM | safe | - | |
| 25 | 35 | MOSIPWM | safe | spi | |
| 26 | 36 | SCKPWM | safe | spi | |
| 27 | 37 | MISOPWM | safe | spi | |
| 28 | 45 | S15PWM | strapping | - | |
| 29 | 46 | S16 | strapping | - | |
| 30 | 47 | S18 | strapping | - | |
| 31 | 48 | S17 | strapping | - | |
| 32 | - | TX | uart | uart | |
| 33 | - | RX | uart | uart | |
| 34 | - | D | safe | - | |
| 35 | - | C | safe | - | |
| 36 | - | DO | safe | - | |
| 37 | - | DI | safe | - | |
| 38 | - | CLK | safe | - | |
| 39 | - | CS1 | safe | - | |
| 40 | - | CS2 | safe | - | |
| 41 | - | SS | safe | spi | |
| 42 | - | USER_LED | safe | - |
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
12 pins · 6 things to knowBOOT_BTNGPIO0 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.
S7GPIO3 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.
S13GPIO9S14GPIO10S4GPIO11S2GPIO12SDAGPIO13SCLGPIO14 General-purpose SPI2 (FSPI) IO MUX pins Other
IO MUX pin of the general-purpose SPI2 (FSPI) bus, not of the in-package flash - that sits on GPIO26-32. The datasheet lists it as a priority-2 pin ("can be freely used without restrictions"), so it is only taken if your board wires flash, an SD card or a display to FSPI.
- S13General-purpose SPI2 (FSPI) IO MUX pin - hold/data line (FSPIHD)
- S14General-purpose SPI2 (FSPI) IO MUX pin - chip select (FSPICS0)
- S4General-purpose SPI2 (FSPI) IO MUX pin - data in (FSPID)
- S2General-purpose SPI2 (FSPI) IO MUX pin - clock (FSPICLK)
- SDAGeneral-purpose SPI2 (FSPI) IO MUX pin - data out (FSPIQ)
- SCLGeneral-purpose SPI2 (FSPI) IO MUX pin - write-protect/data line (FSPIWP)
S15GPIO45 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.
S16GPIO46 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.
S18GPIO47S17GPIO48 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.
- S18Octal SPI differential clock positive leg (SPICLK_P_DIFF), used only by the 1.8 V octal flash/PSRAM variants
- S17Octal SPI differential clock negative leg (SPICLK_N_DIFF), used only by the 1.8 V octal flash/PSRAM variants
Only if you know the tricks
2 pins · 1 thing to knowUSB_DNGPIO19USB_DPGPIO20 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.
- USB_DNUSB OTG negative differential data line (USB_D-)
- USB_DPUSB OTG positive differential data line (USB_D+)
The Crabik Slot ESP32-S3 breaks out 42 pins in total: 31 GPIO for your project.
For peripherals, I²C is mapped to SDA on GPIO13 and SCL on GPIO14, while the SPI bus (MOSI, MISO, SCK, SS) is broken out in full.
On the analog side there are 12 capacitive-touch inputs.
If you want zero surprises, S1, S3, S8, S9 and 13 more are free of any such role - the safest first picks. 12 of the exposed pins carry boot-time or system duties on the ESP32-S3 (BOOT_BTN, S7, S13 and 9 more).
Getting started
flash your first firmware in ~2 minutesBoard: ESP32S3 Dev Module USB CDC On Boot: Enabled Flash Size: 8MB (64Mb) Flash Mode: DIO Partition Scheme: 8M with spiffs (3MB APP/1.5MB SPIFFS) Upload Speed: 921600
// toggle GPIO1 - wire an LED and resistor to it
void setup() {
pinMode(1, OUTPUT);
}
void loop() {
digitalWrite(1, HIGH); delay(500);
digitalWrite(1, LOW); delay(500);
}[env:crabik_slot_esp32_s3]
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 - GPIO1
output:
- platform: gpio
pin: 1
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).Specifications
ESP32-S3 · 50.8 × 50.8 mm · vs other ESP32 chips →Dimensions
About this board
At its core is the ESP32-S3 - a dual-core Xtensa with vector extensions suited to AI workloads.
31 GPIO are broken out - more than most ESP32-S3 boards, so the pin budget is rarely the constraint.
Onboard you'll find a Qwiic connector, a battery fuel gauge (MAX17048), battery charging (MCP73831) via JST-PH 2.0, status LEDs (User, Charge, Power) and Reset/Boot buttons.
It flashes over native USB - no serial-converter driver needed, which isn't a given among ESP32-S3 boards.
- Four Troyka-format module slots (A-D) for plug-in peripherals
- Dual 3.3V 600mA LDO regulators; second regulator is user-controllable
- Automatic power switching between USB and Li-Po battery
Resources
Similar boards
