ALKS ESP32

RoboticsBrno Arduino Learning Kit Starter - an ESP32 education carrier board with buttons, LEDs, buzzers, potentiometers and servo headers.

Micro-USB
ALKS ESP32 board
ESP32
MCU
240MHz
clock
4MB
flash
520KB
SRAM
21· 8 ADC
GPIO
BLE 4.2+ WiFi
radio
On this page

Pinout

21 pins
View:
ALKS ESP32 pinout diagram
PinGPIOLabelsStatusCapabilitiesNotes
10D4SW3strapping-
21TXPWMuartuart
32D3SW2PWMstrapping-
43RXPWMuartuart
54D5L_RGB_RS1PWMstrapping-
65D8L_BPWMstrapping-
712A6PWMstrappingadc
814A5SCLPWMstrappingadc · i2c
915D2A7SW1PWMstrappingadc
1016D6L_RGB_BS2PWMstrapping-
1117D7L_GPWMstrapping-
1218D9PIEZO2S3PWMsafe-
1319D10PIEZO1S4SSPWMsafespi
1421D11L_RGB_GS5MOSIPWMsafespi
1522D12L_RMISOPWMsafespi
1623LED_BUILTIND13L_YSCKPWMsafespi
1725A2PHOTODAC1PWMsafeadc · dac
1826A3DHT_PINDAC2PWMsafeadc · dac
1927A4SDAPWMsafeadc · i2c
2032A0POT1PWMsafeadc
2133A1POT2PWMsafeadc

Start with these

10 pins with no boot or system involvement
D9PIEZO2D10PIEZO1D11L_RGB_GD12L_RLED_BUILTIND13A2PHOTOA3DHT_PINA4SDAA0POT1A1POT2

Freely assignable - no strapping, flash, USB or JTAG duties. Ideal first picks for buttons, sensors and LEDs.

Fine - with a little care

sampled at boot or shared with debug/serial
PinLabelWhat to knowRole
D4GPIO0Must be HIGH during boot for normal startup; if held LOW on reset, forces flash programming mode.Strapping
D3GPIO2If driven HIGH on reset (while IO0 is LOW), selects an unsupported SDIO boot mode, causing boot failure.Strapping
D5GPIO4Sampled at reset for boot config; should not be driven at boot (affects boot mode timing).Strapping
D8GPIO5Must be HIGH during boot; if pulled LOW at reset, alters SDIO slave timing and may prevent normal boot.Strapping
A6MTDI (GPIO12)Keep LOW during boot (internal PD); pulling HIGH at reset selects 1.8V flash mode, causing flash brownout if 3.3V flash is used.Strapping
A5MTMS (GPIO14)Used for JTAG debugging (TMS); driving it as GPIO may interfere with JTAG or produce spurious signals at boot.Other
D2MTDO (GPIO15)Keep HIGH during boot (internal PU); if LOW on reset, bootloader log is silenced and boot mode may change.Strapping

Only if you know the tricks

wired to flash or USB - expect a fight
PinLabelWhat to knowRole
TXU0TXD (GPIO1)Connected to on-board USB-UART for uploading and logs; drives serial output at boot, so using as GPIO can disrupt programming or console.USB
RXU0RXD (GPIO3)Used for receiving data from USB-UART (programming); also pulled HIGH at boot for console communication, so using as GPIO can disrupt uploads.USB
D6GPIO16Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules.Flash
D7GPIO17Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules.Flash
These are recommendations, not hard rules - with the right pull-ups, timing and boot-state awareness most pins can be made to work. When in doubt, start green.
Pinout notes The ALKS ESP32 pinout brings out 21 GPIO pins - every one of them usable in your project. For peripherals, I²C is mapped to SDA on GPIO27 and SCL on GPIO14;…

The ALKS ESP32 pinout brings out 21 GPIO pins - every one of them usable in your project.

For peripherals, I²C is mapped to SDA on GPIO27 and SCL on GPIO14; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO1 and GPIO3 cover serial logging and flashing.

On the analog side there are 8 ADC-capable pins for sensors and battery monitoring and 2 true DAC outputs.

If you want zero surprises, D9, D10, D11, D12 and 6 more are free of any such role - the safest first picks. 7 of the exposed pins carry boot-time or system duties on the ESP32 (D4, D3, D5 and 4 more).

Getting started

flash your first firmware in ~2 minutes
Tool:
1
Connect over USB
Install your USB-serial driver (CH340 / CP210x) if no port appears. Not detected? Hold BOOT while plugging in.
2
Match & flash
Set the Tools options shown, then click Upload.
3
Verify it runs
The onboard LED on GPIO18 blinks - swap the pin if your board's LED differs.
Set these in Tools · leave everything else at default
Arduino IDE 2.x — Tools Copy
Board: "ESP32 Dev Module"
Flash Size: "4MB (32Mb)"
Flash Mode: "DIO"
Partition Scheme: "Default 4MB with spiffs (1.2MB APP / 1.5MB SPIFFS)" (default)
Upload Speed: "921600"
▸ every other Tools option — leave at default
Board: ESP32 Dev Module
Flash Size: 4MB (32Mb)
Flash Mode: DIO
Partition Scheme: Default 4MB with spiffs (1.2MB APP / 1.5MB SPIFFS)
Upload Speed: 921600
Find it: Tools ▸ Board ▸ ESP32 Arduino ▸ ESP32 Dev Module
blink.ino Copy
// blink the onboard LED
void setup() {
  pinMode(18, OUTPUT);
}
void loop() {
  digitalWrite(18, HIGH); delay(500);
  digitalWrite(18, LOW);  delay(500);
}
board to selectesp32dev⧉ copy
platformio.ini Copy
[env:alksesp32]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
upload_speed = 921600
Find it: PlatformIO Home ▸ Boards, search esp32dev — or type it after board =.
board to selectesp32dev⧉ copy
device.yaml Copy
esp32:
  board: esp32dev
  variant: alksesp32
  framework:
    type: esp-idf

# blink - GPIO18
output:
  - platform: gpio
    pin: 18
    id: led_out
light:
  - platform: binary
    name: "LED"
    output: led_out
Find it: search ESPHome's board list for esp32dev (same ids as PlatformIO).
esptool doesn't pick board settings — a prebuilt .bin already has them baked in. This is just the raw flash command.
terminal Copy
esptool.py --chip esp32 --port /dev/ttyACM0 \
  --baud 921600 write_flash 0x0 firmware.bin
--port = your /dev/tty* (macOS/Linux) or COMx (Windows).
Build details: sketch space 1310720 B · data 327680 B · DIO

Specifications

ESP32
Compute
MCU
ESP32
Clock
240 MHz
SRAM · Flash
520 KB · 4MB
Radio
Wi-Fi
802.11 b/g/n
Bluetooth
4.2 LE
Antenna
PCB
I/O
GPIO · ADC
21 · 8
UART · I²C · SPI
3 · 2 · 4
PWM
16 channels
Power
USB
Micro-USB
Serial
-
Boot address
0x1000
Flashing
Upload · OTA
esptool_py · esp_ota
Flash · Boot mode
DIO · DIO
Sketch · Data
1.25 MB · 320 KB
The ALKS ESP32 uses esptool_py for firmware uploads, esp_ota for over-the-air (OTA) updates. Flash mode is DIO with DIO boot mode. The maximum sketch size is 1.25 MB with 320 KB available for data.

About this board

At its core is the ESP32 - a dual-core Xtensa with both Bluetooth Classic and BLE.

Onboard you'll find a buzzer, an ambient-light sensor, status LEDs (Red, Green, Yellow, Blue) and SW1/SW2/SW3 buttons.

  • Educational carrier board for ESP32-DevKitC / Arduino Uno / Nano
  • 2 onboard potentiometers
  • 5 RC servo connectors with external power supply
  • DHT11 sensor connector

Resources

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