unPhone 8
An ESP32-S3 handheld in the unPhone series with a 3.5-inch touchscreen and LoRaWAN radio, for IoT teaching and prototyping.
unPhone 8 Pinout
24 pins| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 1 | SDAA0PWM | safe | adc · i2c | |
| 2 | 2 | SCLA1T1PWM | safe | adc · touch · i2c | |
| 3 | 3 | SSPWM | strapping | spi | |
| 4 | 5 | A4T4PWM | safe | adc · touch | |
| 5 | 6 | A5T5PWM | safe | adc · touch | |
| 6 | 7 | A7T7PWM | safe | adc · touch | |
| 7 | 8 | A2T2PWM | safe | adc · touch | |
| 8 | 9 | A3T3PWM | strapping | adc · touch | |
| 9 | 12 | A11T11PWM | strapping | adc · touch | |
| 10 | 13 | LED_BUILTINA12T12PWM | strapping | adc · touch | |
| 11 | 14 | A6A13T6T13PWM | strapping | adc · touch | |
| 12 | 15 | A8A14T8T14PWM | safe | adc · touch | |
| 13 | 16 | A15PWM | safe | adc | |
| 14 | 17 | A16PWM | safe | adc | |
| 15 | 18 | A17PWM | safe | adc | |
| 16 | 19 | A18PWM | uart | adc | |
| 17 | 20 | A19PWM | uart | adc | |
| 18 | 27 | A10T10PWM | strapping | adc · touch | |
| 19 | 33 | A9T9PWM | safe | adc · touch | |
| 20 | 36 | RXPWM | uart | uart | |
| 21 | 37 | TXPWM | uart | uart | |
| 22 | 38 | SCKPWM | safe | spi | |
| 23 | 39 | MOSIPWM | strapping | spi | |
| 24 | 40 | MISOPWM | strapping | spi |
Start with these
14 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
7 pins · 4 things to knowSSGPIO3 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.
A3GPIO9A11GPIO12LED_BUILTINGPIO13A6GPIO14 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.
- A3General-purpose SPI2 (FSPI) IO MUX pin - hold/data line (FSPIHD)
- A11General-purpose SPI2 (FSPI) IO MUX pin - clock (FSPICLK)
- LED_BUILTINGeneral-purpose SPI2 (FSPI) IO MUX pin - data out (FSPIQ)
- A6General-purpose SPI2 (FSPI) IO MUX pin - write-protect/data line (FSPIWP)
MOSIGPIO39 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.
MISOGPIO40 JTAG test data out pin (MTDO) JTAG
Default JTAG TDO output for debugging. Using it as GPIO will interfere with JTAG debugging functionality.
Only if you know the tricks
3 pins · 2 things to knowA18GPIO19A19GPIO20 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.
- A18USB OTG negative differential data line (USB_D-)
- A19USB OTG positive differential data line (USB_D+)
A10GPIO27 SPI0/1 memory-bus hold/data line (SPIHD; DQ3 in 8-line mode) Flash
Part of the SPI0/1 bus that runs the in-package flash and PSRAM, listed by the datasheet as "already allocated or not recommended for use". Modules keep these lines internal, so the pin is not available as GPIO.
All 24 pins on the unPhone 8 are usable GPIO.
Peripheral wiring is straightforward: I²C is mapped to SDA on GPIO1 and SCL on GPIO2; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO37 and GPIO36 cover serial logging and flashing.
Beyond plain digital I/O you get 18 ADC-capable pins for sensors and battery monitoring and 12 capacitive-touch inputs.
7 of the exposed pins carry boot-time or system duties on the ESP32-S3 (SS, A3, A11 and 4 more) - check the guidance above before wiring anything to them. SDA, SCL, A4, A5 and 10 more are free of any such role - the safest first picks.
Getting started
flash your first firmware in ~2 minutesBoard: ESP32S3 Dev Module USB CDC On Boot: Enabled Flash Size: 8MB (64Mb) Flash Mode: DIO PSRAM: QSPI PSRAM 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:unphone8]
platform = espressif32
board = esp32-s3-devkitc-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600
board_build.arduino.memory_type = qio_qspi
build_flags = -DBOARD_HAS_PSRAMesp32-s3-devkitc-1 - or type it after board =.esp32:
board: esp32-s3-devkitc-1
variant: esp32s3
framework:
type: esp-idf
psram:
mode: quad
speed: 80MHz
# 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 · vs other ESP32 chips →About this board
Inside sits the ESP32-S3 - a dual-core Xtensa with vector extensions suited to AI workloads.
Around the module: 8MB (QSPI) PSRAM, a TFT 3.5" 320x480 display with touch, a microSD slot, LoRa (RFM95W), an IMU, an IR transceiver, battery charging (BQ24295) and Button 1/Button 2/Button 3/Reset buttons.
It flashes over native USB - no serial-converter driver needed, which isn't a given among ESP32-S3 boards.
- TCA9555 16-bit I²C GPIO expander
- Vibration motor
- 3 discrete indicator LEDs (red / green / blue)
- Hardware power on/off switch
- Bundled backplane with two FeatherWing sockets & prototyping area
Resources
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