2. Frequency meter

About

Mode used for measuring signal frequency. Display shows current reading in Hertz or Megahertz units.

Details

• Measure signal frequency at DIG1 pin.
• Maximum frequency up to 23 MHz*.
• Input pin is pulled HIGH (default state).
• Display is updated each second.
• Display will show value in Hertz. If number exceeds 1Mhz - it will switch to Mhz mode.
• Signal HIGH level should be in the amplitude from 2 V to 5 V.
• Left corner LED DIG1 will blink according to input frequency.
  It is not directly tied to input pin. Only for visual representation.

* Frequencies larger than 10MHz can be affected by electrical conditions (contacts, wire length, no shielding, etc.). Make sure wires are short and signal is stable enough.

Controls

Enter mode:

• Select Menu > 2. FREq.
• (deprecated) In Main screen hold SET- for 3 seconds.

Exit mode:

• Open menu and select other mode.
• (deprecated) Press SET- to exit to Main screen.

Example

1. Connect D9 digital pin to DIG1 frequency meter input.
2. Enter frequency meter mode by selecting Menu > 2. FREq.
3. Load code sketch to TotemDuino. This will output 1kHz frequency on pin D9.
   LabBoard should display 1000 HZ. Uses tone() function.

   void setup() {
     pinMode(9, OUTPUT); // Set pin D9 to output
     tone(9, 1000); // Output 1kHz frequency to pin D9
   }
   void loop() {
   
   }
   

4. Load code sketch to TotemDuino. This will output 8Mhz frequency on pin D9.
   LabBoard should display 8.00000mHZ. Letter 'm' displayed as 2 segments.

   void setup() {
     // Set pin D9 to output
     DDRB |= (1 << PB1);
     // Set timer TOP and compare values
     ICR1 = 1;  // TOP
     OCR1A = 0; // compare (duty cycle)
     // Set no prescaler, Fast PWM mode (14)
     TCCR1A = (1 << COM1A1) | (1 << WGM11) ;
     TCCR1B = (1 << CS10) | (1 << WGM12) | (1 << WGM13);
   }
   void loop() {
   
   }
   

   This code snippet directly writes ATmega328P registers to configure timer 1 to output 8Mhz frequency on pin PB1 (D9).