FH4R2-class resources, 2 MB PSRAM, native USB.
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CONTROLLERESP32-S3 / 4 MB DISPLAYST7796U / 480 × 320 RADIOExternal ExpressLRS / CRSF BOUNDARYNo approved battery pack
reference hardware
Build the control surface around known parts.
SourceTX defines the electrical interfaces for a reproducible reference transmitter. This page separates the tested firmware target from the power system, enclosure, and other product decisions a builder still owns.
Landscape touch interface.
400 kbaud signal path on GPIO 42.
Battery, charger, enclosure, and RF module remain builder-selected.
parts checklist
What you need
Start with the reference interfaces below. Use the installation guide and electrical boundaries before powering a connected vehicle or radio module.
01 / MCUCORE
ESP32-S3 controller board
Use an ESP32-S3-FH4R2 configuration or a SuperMini-class carrier that exposes the same resources and pins.
- 4 MiB quad-I/O flash
- 2 MiB PSRAM
- Native USB available
- 3.3 V GPIO logic
02 / DISPLAYUI
ST7796U TFT + FT6x36 touch
A 480 × 320 ST7796U panel in landscape rotation with an FT6x36-family capacitive touch controller.
- Touch I²C address 0x38
- Shared I²C bus with INA219
- SPI display interface
- Backlight control on GPIO 3
03 / CONTROLSINPUT
Two analog controls + five buttons
Use two potentiometers with ADC-safe endpoints for steering and throttle, plus five active-low navigation buttons wired to ground.
- Steering wiper: GPIO 6
- Throttle wiper: GPIO 5
- Navigation: GPIO 35–39
- Common logic ground required
04 / MONITORINGPOWER
INA219 battery monitor
The transmitter battery monitor connects over I²C and uses the sensor’s normal default address. It measures; it does not manage or charge the battery.
- I²C SDA: GPIO 8
- I²C SCL: GPIO 9
- INA219 default address
- Warning-only battery policy
05 / RADIOCRSF
ExpressLRS / CRSF module path
Use an external radio module, a suitable antenna, a compatible receiver, and a safe test load. The firmware provides the signal path, not RF power.
- CRSF signal: GPIO 42
- Single-wire UART
- 400 kbaud
- Connect the approved antenna before RF power
06 / OPTIONALFEEDBACK
Voice or haptic add-ons
Optional outputs can drive a properly powered feedback stage. A DFPlayer Mini-compatible voice module is supported when configured with its own microSD and speaker/amplifier path.
- Never power loads from GPIO
- Use suitable drivers and protection
- Follow module voltage guidance
- Keep UART assignments unique
default wiring
Reference pin map
These are the default tested assignments. Compatible wiring revisions can use the browser or companion configuration tools, but a changed profile is a new untested wiring revision.
| Function | Connection | Notes |
|---|---|---|
| Steering potentiometer | GPIO 6 | 12-bit ADC input |
| Throttle potentiometer | GPIO 5 | 12-bit ADC input |
| CRSF signal | GPIO 42 | Single-wire UART / 400 kbaud |
| Navigation buttons | GPIO 35–39 | Active-low, internal pull-ups |
| I²C bus | GPIO 8 / 9 | SDA / SCL, touch + INA219 |
| Display control | GPIO 2, 3, 7, 10, 13, 14 | Clock, backlight, MOSI, reset, D/C, CS |
Important:SourceTX does not currently certify a finished transmitter, battery, charger, protection circuit, enclosure, or RF-module combination. Never connect battery voltage to an ADC or GPIO, and never power a radio, motor, haptic motor, buzzer, or backlight directly from an ESP32 pin.Open public installation resources →