TFI2CADC01

TFI2CADC01 — I²C 16‑bit ADC for UAVs

Compact 4‑channel analog‑to‑digital converter module for Pixhawk‑class autopilots and ThunderFly form‑factor carrier boards. Based on TI ADS1115 (16‑bit Σ‑Δ ADC). Dual Pixhawk JST‑GH I²C ports support in‑line daisy‑chaining.

Key features

• 4 × single‑ended inputs (AIN0…AIN3) up to VDD range (0–3.3 V)
• 16‑bit ADC (ADS1115IDGS) with programmable gain amplifier (PGA)
• I²C interface, 100/400 kHz compliant; on‑board 4.7 kΩ pull‑ups to 3.3 V
• ADDR solder-bridge for selectable I²C address (default 0x48)
• ALERT/RDY interrupt output (optional test‑point)
• Bus‑powered from +5 V; on‑board LDO to internal 3.3 V
• Input/rail protection and status LEDs (PWR, activity)
• Two JST‑GH 4‑pin I²C ports for Pixhawk; one 2×4 header for access to analog inputs and ground

Electrical

• Input supply (JST‑GH VBUS): 5.4 V (Pixhawk I²C standard)
• I²C levels: 3.3 V (pull‑ups on board)
• Analog input range: 0…3.3 V (referenced to GND)
• ESD / surge: front‑end and bus clamped (5.6 V TVS on 5 V)

⚠️ Do not exceed 3.3 V on AINx relative to GND.

Connectors & pinout

JST‑GH I²C (J2, J3) — Pixhawk standard

Pin 1: VBUS +5V
Pin 2: SCL
Pin 3: SDA
Pin 4: GND

Both ports are wired in parallel for pass‑through/daisy‑chain.

I²C addressing

Default assembly is 0x48.

The board provides pads/jumper position for changing the address. See silkscreen near ADDR.

Jumpers / test points

• T1 (ALERT/RDY): routes the ALERT/RDY pin to a test pad for optional host interrupt. Leave open if unused.
• JP2/JP2: board address option tie (factory) to 3.3 V.

LEDs

• PWR (green): 3.3 V power rail present.
• ACT (orange): activity/diagnostic (wired to logic as per schematic option).

Typical wiring (Pixhawk)

1. Plug either JST‑GH port to a Pixhawk I2C port (5 V provided by autopilot).
2. Daisy‑chain additional I²C node from the second JST‑GH if needed.
3. Connect sensors to AIN0…AIN3 via J1, or wire your signals to the corresponding pads.
4. (Optional) Strap ADDR and solder for a non‑default address if multiple TFI2CADC01 are present on the same I2C bus.

Software notes (ADS1115)

• PX4 support: PX4 Autopilot includes a native driver for ADS1115 (16‑bit, up to 860 SPS, 4‑channel delta‑sigma ADC with PGA, oscillator, internal VREF, comparator and I²C). See PX4 driver and TI ADS1115.
• Use cases: Pixhawk‑compatible ADC module is suitable for prototyping/attaching analog‑output sensors (e.g., temperature, humidity, gas presence, etc.).
• Configuration tips: configure PGA for expected full‑scale to maximize resolution; for single‑ended reads use MUX AIN0/1/2/3 vs GND; to minimize I²C polling enable comparator in "traditional" mode and read ALERT/RDY (if T1 is wired).

Example (Linux i2c-tools)

# Detect
sudo i2cdetect -y 1

# Read a register (conversion register 0x00)
sudo i2cget -y 1 0x48 0x00 w

Mechanical & form factor

PCB follows the ThunderFly form factor for avionics modules (mounting & stacking compatible with TF carriers). Two JST‑GH side‑by‑side for easy in‑line installation inside UAV wiring harnesses.

Revision history

• TFI2CADC01A - Initial revision

Availability and Customization

The TFI2CADC01 is available from ThunderFly s.r.o. For a commercial quotation, contact us at sale@thunderfly.cz or shop via our Lectronz or Tindie store.

We also offer application‑specific modifications on request. Typical options include alternative input scaling (dividers/shunts), connector or cable variations, pre‑strapped I²C addresses, and simple mounting adaptations. Basic changes are usually provided at no additional cost with an estimated lead time of approximately three weeks.