Reading fan speed with 16F877A

[Van.Helsing]

Hi!

  Anyone know how can read the pulses of a three pin fan using the 16F877A ?

  I know how to calculate and find something in ASM, but i need in C.

  []'s
  Ismael

[frasenci]

Ismael , I have succesfully done it using an Infrared - Reflective Sensor .
Only need an distinctive ( white over black ... ) line once on the rotating part. Maths are simple.
Sensor must get close to moving part ( about 2 mm )
I have used Protons Pulsein command but that you can do in ASM also.
Good results , I used in a Glow Engine speed control for an R/c Helicopter. ( Governor )

Tell me if this direction is usefull for you
greetings


 

[hemlig]

You might get some ideas on how to read the pwm from various types of fans
and then adapt it to a PIC by reading this appnote at this website:

http://www.maxim-ic.com/appnotes.cfm/appnote_number/1784/