Measures capacitance and displays value on a OLED Display using an ATTiny85 (Digistamp)
- Based on ATTiny85 (DigiStamp)
- SSD1306 0.96" OLED Display
- Frequency measurement for low value capacitors 1pF - 1uF using 555 oscillator
- Charge time measurement for high value capacitors 1uF - 50000uF
- 2 separate ports used for the methods to minimise stary capacitance
- Two values of current used for Charge Time to minimise time for large capacitors
- 555 method self zeros at start up, can be rezeroed with push button
- A quick test used to select which method should be used for each cycle of measurement.
- Charge time method accuracy can be improved by support for OSCVAL clock frequency adjustment
555 timer method uses a base frequency determined by a known capacitance (~ 1nF) (~15KHz) Capacitance in parallel with this lowers the frequency Frequency measured by pulse counting over a period of about 1 second and capacitance calculated.
Charge method first discharges the capacitor to 0V using a MOSFET. One of 2 currents is then selected via a MOSFETto start charging. ADC is used to detect when 50% threshold is reached and capacitance calculated.
Measurement method is determined by using a quick charge method to see if any capacitance is on the high value port and if so what current should be used.
Used Additional URL https://raw.githubusercontent.com/ArminJo/DigistumpArduino/master/package_digistump_index.json