Speedometer digital 2digit in 7segment with attiny2313

[erwin4838]

Dear all
i'm new beginning in here,can't you help to build Speedometer digital 2digit 7segment with attiny2313,the detail principle as follows attached files
thanks for you attention

 

[wkrug]

You should use a internal Timer that's running free. Best using a 16 Bit timer.
Further you have to use a Crystal for Time Base.

Connect the Sensor - the signal have to be TTL compatible - to the ICP Pin of the uses Timer.

In the Timer Overflow Interrupt routine implement a a counter the counts up the Overflows.

The Princip is the following.

The internal timer runs and counts up.
When the Plate give an impulse by the sensor the actual counter was stored in th ICP Registers of the Counter.
Now subtract the Counter and Overflow Counter from the last Values.

With the Crystal Clock, the Prescaler and the Counter values you can calculate the Speed of the Wheel, every when passing of the plate near the sensor.

 

[erwin4838]

i'm sory can you help me to give example source code and schematic ?

 

[wkrug]

I've done this at my telemetry transmitter ( Telemetrie Sender ).
Look here: **broken link removed**

Sourcecode: **broken link removed**

I've done this with with INT1 Interrupt routine there and not in the ICP.
The rotation relevant parts are:

//Count Pulses to avoid overflow
// External Interrupt 1 service routine Drehzahlmesser impulseingang
interrupt [EXT_INT1] void ext_int1_isr(void)

//Count Up the Overflow Counters of Timer 0
// Timer 0 overflow interrupt service routine Drehzahlmesser Pulsdauermessung
interrupt [TIM0_OVF] void timer0_ovf_isr(void)

That Part middles the Values over one second:
// Timer 1 output compare A interrupt service routine
interrupt [TIM1_COMPA] void timer1_compa_isr(void)

This Part Calculates the rpm with entire values on 8MHz Controller clock:

if (ui_drpulses<3)      /* Drehzahlen unter 120 U/min werden ignoriert */
{
    li_drehzahl=0;
}
else
{
    if (ui_drpulses<350) /* Entscheidung welches Drehzahlermittlungsverfahren angewendet wird bei 21000 U/min*/
    {
        li_drmittel=li_drmittel/uc_stellen;        /* Mittelwert der Drehzahlmessungen errechnen */
        li_drehzahl=7500000/(li_drmittel*uc_blatt);  /* Periodendauermessung */
    }
    else
    {
        li_drehzahl=ui_drpulses;                   /* Pulszählung in Torzeit ( 1Sekunde )*/
        li_drehzahl=(li_drehzahl*60)/uc_blatt;
    }
}
ui_drpulses=0;   /* Pulszählung zurücksetzen */
li_drmittel=0;   /* Mittelwertbildner zurücksetzen */
uc_stellen=0;    /* Stützstellenzähler zurücksetzen */

That are the Settings for Initialisation:

// Timer/Counter 0 initialization
// Clock source: System Clock
// Clock value: 125,000 kHz
TCCR0=0x03;
TCNT0=0x00;

// Timer/Counter 1 initialization
// Clock source: System Clock
// Clock value: 1000,000 kHz
// Mode: Normal top=FFFFh
// OC1A output: Discon.
// OC1B output: Discon.
// Noise Canceler: Off
// Input Capture on Falling Edge
// Timer 1 Overflow Interrupt: Off
// Input Capture Interrupt: Off
// Compare A Match Interrupt: On
// Compare B Match Interrupt: Off
// CTC Mode : On
TCCR1A=0x00;
TCCR1B=0x0A;
TCNT1H=0x00;
TCNT1L=0x00;
ICR1H=0x00;
ICR1L=0x00;
OCR1AH=0xC3;
OCR1AL=0x4F;
OCR1BH=0x00;
OCR1BL=0x00;

...

// External Interrupt(s) initialization
// INT0: Off
// INT0 Mode: Falling Edge
// INT1: On
// INT1 Mode: Falling Edge
GICR|=0x80;
MCUCR=0x0A;
GIFR=0xC0;

That routine works only at >120rpm. You should correct the parameters for your application.