openQCM Wi2Counting cycles, precisely.
openQCM Wi2 exploits the potential and simplicity of the Teensy microcontroller — an Arduino-compatible board with a 32-bit ARM processor. A high-precision quartz crystal oscillator automatically tracks frequency changes.
- Instrument
- openQCM Wi2
- Sheet
- 04 / 06
- Title
- Electronics
- Drawn
- openQCM · Pompeii
The signal path
- U1Quartz crystalin the sensor module, on two pogo pins
- U2Pierce oscillatorSN74LVC1GX04: keeps the crystal at resonance
- U3Square waveone edge per oscillation
- U4Teensy counterFreqCount: edges counted over a 1 s gate
- U5USBfrequency and temperature to the software
One count per second.
Every detail is designed to simplify the researcher’s experimental activity. Frequency is measured using the FreqCount library, which counts the number of pulses during a fixed time using the microprocessor’s hardware timer — a procedure that works very well at high frequencies, where many cycles are counted within the gate interval (typically 1 second).
Wireless-ready.
A compact, USB-powered driver designed for wireless-ready acquisition — high-precision oscillator tracking in a footprint small enough for any benchtop or field setup. Expansion headers on the board take a Wi-Fi module or a PCB of your own.
The boards
- Main board
- 2 layers, 59.9 × 36.8 mm, FR-4 TG150, 1.6 mm, 1 oz copper, ENIG
- Oscillator
- SN74LVC1GX04, Pierce topology
- Regulator
- LP2985, clean 3.3 V supply
- Expansion
- Headers for a Wi-Fi module or custom PCB
- Proximity board
- 31 × 29 mm, MCP9808 (±0.25 °C), two pogo pins, status LED, USB 3.0 connector to the main unit
- Schematics
- Open source