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ARDUINO FREQUENCY COUNTER FOR ANDROID

The Android app is made using MIT App Inventor which is an easy way to make Android apps. http://appinventor.mit.edu/explore/ . The app has
buttons to connect and disconnect the Bluetooth to the phone and 2 displays of voltage and frequency. The .apk file is the file that installs
manually the app to your phone. The .aia file can be imported after you install the MIT App Inventor.
The Arduino generates an accurate 1 second time base for the counter by cascading timer0 and timer2. The link between digital inputs 3 and 4 connects the output of timer2, 250 Hz, to input of timer0. The software waits for the output of timer0 to go positive to start the count of frequency input to timer1. Timer1 is a 16 bits timer, it overflows at the count of 32768, that in turn advances overFlow register. At the end of the 1 second the 16 bit register is recorded. The Arduino then sends to the Bluetooth 5 bytes of data in serial RS232 protocol.
HC-05 is pre-set to code 1234 and name HC-05. The serial RS232 is pre-set to 9600,n,8,1.

PIC16F690 FREQUENCY COUNTER FOR ANDROID

This project is for the Android app and HC-05 as above. The PIC counts the frequency over 1 second period generated by CCP1 and Timer1. Input is counted by Timer0 that can count up to 4 MHz. After each count period 2 bytes of ADC and 3 bytes of the counter are transmitted to the HC-05 Bluetooth module.


You are free to use the circuit diagram and the software with no limitations.

 

The Android app

 

Circuit Description
See also Technical Tips

1K resistor is for reducing 5V to 3.3V input of the Bluetooth module.
HC-05 module can be any make that is powered by 5V, from ebay.
The Arduino can be powered by the android device using OTG cable.

Circuit Description
See also Technical Tips

1K resistor is for reducing 5V to 3.3V input of the Bluetooth module.
HC-05 module can be any make that is powered by 5V, from ebay.