Display Speed on LED

[koolguy]

Hello Guys,
How to display speed i mean of the sensor is giving pulse per km per min and i want in km i will simply divide it by 1000.
after that display is this right or using capture ?

 

[analog1]

redifine your question km to km?

 

[koolguy]

Hello,
There is a pulse which rise after 10 meters in motor via sensor of 24V etc
so, I have to count the pulse and convert it in km and after that it is to be displayed in display per min km!

 

[jpanhalt]

Hello,
There is a pulse which rise after 10 meters in motor via sensor of 24V etc
so, I have to count the pulse and convert it in km and after that it is to be displayed in display per min km!

Presumably, if you get a pulse every time the motor moves 10 meters, then the vehicle has also moved 10 meters. Why do you propose dividing by 1000 to get kilometers? Dividing by 100 will give kilometers, plus or minus, but that won't give you your velocity unless you also measure the lapsed time.

John

 

[koolguy]

Sorry,
Actually i want a led display which will show in 4 digit the speed of machine.
using a proximity sensor of 24V regularly after 10 meters completion of rotating wires on it.
it is converted to km per min speed real time.
using pic16f877 hi tech c compilers

 

[Ian Rogers]

Sorry,
Actually i want a led display which will show in 4 digit the speed of machine.
using a proximity sensor of 24V regularly after 10 meters completion of rotating wires on it.
it is converted to km per min speed real time.
using pic16f877 hi tech c compilers

This is what I want you to post!!! Clear posts that anyone can understand!! Look at your first post, then look at this one.... BIG difference..

How many pulses per revolution.. how many revs make up one metre?

 

[Les Jones]

Unless the speeds being measured are very high it is not practical to count pulses in a specific time period. You will have to measure the time between pulses then divide into a constant to convert the the time period to speed. So IF the last information is correct then if you measure the time between pulses (Using the units of time in seconds) then the speed (Km per minute) will be 0.6 divided by the time between pulses
(1 pulse per second = 10 metres per second = 600 metres per minute = 0.6 Km per minute)
I am not clever enough to write the code for you in "C". I work in assembler.

Les.

 

[koolguy]

I am not clever enough to write the code for you in "C". I work in assembler.

What clever mean here?

 

[koolguy]

How many pulses per revolution.. how many revs make up one meter?

Don't know i will change it in code as per requirement.

 

[Ian Rogers]

In my payout meters I use a constant to determine speed and payout... My systems have 16 pulses per revolution and each cable has different rollers... most are around 4 revs per metre so I count 64 pulses per metre.

The constant is changeable in a menu so I can cater for several sizes...

What clever mean here?

Les said that he hasn't had the chance to learn C so he uses asm!!

 

[koolguy]

What is the procedure to build km per min speed meter on 7 segments?

 

[Ian Rogers]

7 segments or 7 digits?

If you use the 74hc595 then you can just add digits! Once assembled you just load them all and display!

 

[Les Jones]

You could also multiplex the 7 segment displays driving the segments using one 8 bit port and using another port to drive the bases of the digit drive transistors. You can see an example of this in the simple tachometer design on my website https://lesjhobbies.weebly.com/
You might also find this thread useful as it discusses possible problems measuring the period of pulses.
https://www.electro-tech-online.com/threads/pic-ccp-module-capturing-low-frequency-periods.145153/

Les.

 

[koolguy]

I multiplex till now shift register is also good idea to remove flickers.
and what is the procedure to read the pulse?
is it compare capture??

 

[Ian Rogers]

Just straight into the timer... You can increment timer 0 on RA4 ( 8 bit) or timer 1 0n RC0 (16 bit)..

Lets say you set up timer 1 to count incoming pulses on RC0 and set timer 0 to count to 1 second

Timer 0 clear
Timer 1 clear
while timer 0 < second
      let timer 1 increment

read timer 1

timer 1 has pulses per second!!!

 

[MaxHeadRoom78]

I have used this as a basis for some low RPM projects, It can be readily adapted for extended display or rate, also can be adapted to CCP instead of simple TMR1 capture.
I have the code for the one shown but it is in Assembly as this is also what I work in.
Max.

 

[koolguy]

i have never use ccp ever.

 

[koolguy]

The 7 segment Display in circuit use less wires to drive leds, why?

 

[Les Jones]

If you are talking about Max's schematic then it is the shorthand method of drawing the lines that is confusing you. A line with a / across it and a number means there are that number of conductors. For example from RB0:RB6 is actually 7 wires.

Les.

 

[jpanhalt]

The 7 segment Display in circuit use less wires to drive leds, why?

Which circuit? Less than what? How many do you expect for each 7-segment digit?

The circuit posted by Max (post #16) has 7 wires to each digit plus ground.4

John

Les Jones , Sorry, I write very slowly.