tachometer

fogassa · Joined: 19 Dec 2005 Posts: 3

HI All,
I'm tring to make a simple tachometer that reads from 100 to 65000 rpm.and display it on lcd
I'm using bascom and at90s2313 with 4mhz cristal(can use 10mhz)
I've adapted the code bellow from BAsic stamp, I can get a reading but it's not correct.
I've read thebascom help files but not much about pulsein, it says it will increment count by 10us but that varies with cristal.
If I'm using a 4mhz cristal what is the pulsein increment?
Could someone point me in the right direction?

Dim Rpm As Word
Config Portb = Output
Config Portd = Input
Portd = 255 'enable Portd pullup's

Config Lcdbus = 4
Config Lcd = 16 * 2
'Config Lcdpin = Pin , Db4 = Pb.4 , Db5 = Pb.5 , Db6 = Pb.6 , Db7 = Pb.7 , E = Pb.3 , Rs = Pb.2
Cls
Cursor Off Noblink
Cls

Tach:
Do
Wait 1
Pulsein Rpm , Pind , 6 , 1
Rpm = Rpm / 100
Rpm = 60000 / Rpm

Cls
Lcd "RPM ;rpm
Loop

'----

Fogassa.

kazi · Joined: 21 Oct 2005 Posts: 19 Location: Cape Town

Hi

I hope I can still help you.

The way I did it is to count the amount of pulsses per second.

I used a 1 second timer and in0 or in1 to count the pulses.

If you have the amount of pulses/second (hz) then you can convert to rpm.

erwin4838 · Joined: 24 Feb 2012 Posts: 39 Location: Indonesia

can u share output 2digit with 7segment,tks