openQCM Wi2 exploits the potentiality and simplicity of the Teensy microcontoller, an arduino compatible development board equipped with a 32 bit ARM processor. The electronic circuit is based on a high precision quartz crystal oscillator which automatically tracks in the frequency changes. The new openQCM Wi2 electronics is now capable of measuring frequency up to 65 MHz, allowing you to use a wide range of quartz sensors with different sensitivities
The SN74LVC1GX04 is designed for creating a crystal oscillator circuit with a buffered square-wave output. According to Pierce’s oscillator topology, the first inverter is used as a linear amplifier for crystal oscillator and the last three inverters guarantees a fast edge square-wave at the output.
Frequency is measured using the library FreqCount, which counts the number of pulses during a fixed time using the microprocessor hardware timer. This procedure works very well at high frequencies, because many cycles can be counted during gate interval. Typical gate time interval is set to 1 second. Teeny 3.2 is capable to measure frequency from 1 kHz up to 65 MHz.
Thanks to the integration of the add-on module based on ESP8266 you can add internet to openQCM Wi2 device. ESP8266 module is an highly-integrated 80 MHz Wi-Fi microcontroller operating both as an access point and as a client. It has a TCP/IP stack with DNS support giving to the Teensy microcontroller Wi-Fi ability. This add-on module will give you the ability to monitor your experiment through any mobile device connected to your network.