help to build digital car speedo meter

[kamalsolimen]

hello

i start to build digital car speedo meter i have honda civic 93

i dont know Vehicle Speed Sensor output its frequency or voltage , mhz = volt = speed

i will use pic16f877a and LM2907 if output is frequency

and i need help to build circuit digram

thanks

 

[Ian Rogers]

It's derived from the same sensor that has always been in the gearbox.... Frequency.. I can't tell you how many pulses per wheel revolution... This will not be written down anywhere..... The pic will be able to monitor the frequency directly.... You could just use the CCP module....

You would need to monitor the frequency output at a know speed to work out the frequency....

 

[kamalsolimen]

sorry i have little experience in electronic whats is CCP module

 

[ronsimpson]

The abbreviation CCP stands for Capture/Compare/PWM.
**broken link removed**
There are many different ways to use a timer.
It is possible the signal from the speedometer cable too fast for the computer to count so a timer can count very fast and help the software.

 

[kamalsolimen]

thanks i will try