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

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Pinout
21 pins| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 0 | D4SW3 | strapping | - | |
| 2 | 1 | TXPWM | uart | uart | |
| 3 | 2 | D3SW2PWM | strapping | - | |
| 4 | 3 | RXPWM | uart | uart | |
| 5 | 4 | D5L_RGB_RS1PWM | strapping | - | |
| 6 | 5 | D8L_BPWM | strapping | - | |
| 7 | 12 | A6PWM | strapping | adc | |
| 8 | 14 | A5SCLPWM | strapping | adc · i2c | |
| 9 | 15 | D2A7SW1PWM | strapping | adc | |
| 10 | 16 | D6L_RGB_BS2PWM | strapping | - | |
| 11 | 17 | D7L_GPWM | strapping | - | |
| 12 | 18 | D9PIEZO2S3PWM | safe | - | |
| 13 | 19 | D10PIEZO1S4SSPWM | safe | spi | |
| 14 | 21 | D11L_RGB_GS5MOSIPWM | safe | spi | |
| 15 | 22 | D12L_RMISOPWM | safe | spi | |
| 16 | 23 | LED_BUILTIND13L_YSCKPWM | safe | spi | |
| 17 | 25 | A2PHOTODAC1PWM | safe | adc · dac | |
| 18 | 26 | A3DHT_PINDAC2PWM | safe | adc · dac | |
| 19 | 27 | A4SDAPWM | safe | adc · i2c | |
| 20 | 32 | A0POT1PWM | safe | adc | |
| 21 | 33 | A1POT2PWM | safe | adc |
Start with these
10 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
sampled at boot or shared with debug/serial| Pin | Label | What to know | Role |
|---|---|---|---|
| D4 | GPIO0 | Must be HIGH during boot for normal startup; if held LOW on reset, forces flash programming mode. | Strapping |
| D3 | GPIO2 | If driven HIGH on reset (while IO0 is LOW), selects an unsupported SDIO boot mode, causing boot failure. | Strapping |
| D5 | GPIO4 | Sampled at reset for boot config; should not be driven at boot (affects boot mode timing). | Strapping |
| D8 | GPIO5 | Must be HIGH during boot; if pulled LOW at reset, alters SDIO slave timing and may prevent normal boot. | Strapping |
| A6 | MTDI (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 |
| A5 | MTMS (GPIO14) | Used for JTAG debugging (TMS); driving it as GPIO may interfere with JTAG or produce spurious signals at boot. | Other |
| D2 | MTDO (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| Pin | Label | What to know | Role |
|---|---|---|---|
| TX | U0TXD (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 |
| RX | U0RXD (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 |
| D6 | GPIO16 | Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules. | Flash |
| D7 | GPIO17 | Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules. | Flash |
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 minutesBoard: 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
// blink the onboard LED
void setup() {
pinMode(18, OUTPUT);
}
void loop() {
digitalWrite(18, HIGH); delay(500);
digitalWrite(18, LOW); delay(500);
}[env:alksesp32]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
upload_speed = 921600esp32dev — or type it after board =.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_outesp32dev (same ids as PlatformIO).esptool.py --chip esp32 --port /dev/ttyACM0 \
--baud 921600 write_flash 0x0 firmware.bin--port = your /dev/tty* (macOS/Linux) or COMx (Windows).Specifications
ESP32About 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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