Counter programing in 8051 using asm language

[Genovator]

Re: to count pulses using 8051

They must have used band pass filter to sort out that specific frequency. But when the robot is in a market it will find many voices of same frequency. Anyway, you can give it a try...

 

[Disha Karnataki]

Re: to count pulses using 8051

as you have mentioned about ir sensors that they can sense only when direct line-of-sight then i can use 3 or 4or may be 5 ir receiver sensors to detect the motion of the person in any direction.

 

[Genovator]

Re: to count pulses using 8051

Yes. You can use around 5 IR receivers placed with around 20 or 25 degree angle in between, covering a total of say 120 or 150 degree on the front. Each should be isolated with each other by a wall in between. Check which receivers are receiving input and you can assume the direction.

 

[milan.rajik]

Re: to count pulses using 8051

If you are still trying to find the RPM of your fan then use hall sensor and a magnet instead of IR LED and photo diode/transistor.

 

[Disha Karnataki]

Re: to count pulses using 8051

yes yes correct then now i will be doing a receiver using tsop1738 and a transmitter fixed on person.
i have read that tsop1738 can detect only 38khz frequency is that suffecient i mean upto what distance(approx) it might detect. if not which is best possible frequency should i choose.

 

[Genovator]

Re: to count pulses using 8051

Frequency doesn't matter. Its just the carrier frequency. TSOP1738 is commonly available. The only thing matters for the distance is the IR transmitters power. You can make the transmitter as a strobe with constant flashing of say 0.5s on and 0.5s off. On the receiver end keep checking for such strobe signal. This way you can sort out the desired signal from any other interference and the bot will not confuse where to go.

Remember, TSOP1738 will amplify and demodulate the signal and will produce plain NRZ signal on output, probably inverted (don't remember). So any stray signal with 38khz carrier will also be accepted and mixed with the desired signal. So if you can get a hold on 1730, it could be better.

 

[Disha Karnataki]

Re: to count pulses using 8051

actually that trolly which will be following is very huge(i mean it is not reliable to be using simple dc motors) then what kind of motors i will have to use as it will also has to carry weight.

 

[Genovator]

Re: to count pulses using 8051

I am not good in mechanics but I guess you will need some high torque electric motors with gear and low RPM. I don't know how to calculate it. You can start a thread for that.

 

[Disha Karnataki]

Re: to count pulses using 8051

this is the link of my project pov on table fan:
https://www.youtube.com/watch?v=7B6xbq6lUIg

 

[Genovator]

Re: to count pulses using 8051

That was really nice!!! Good work....

 

[Disha Karnataki]

Re: to count pulses using 8051

thank you..:razz:
they have started teaching us about micro controllers.As our sir was describing about the pin no 18 & 19 of 8051 where crystal oscillator is connected.
And as we use crystal oscillator to get time delays.
suppose if i don't use crystal oscillator then will the uc produce time delays?? The 8051 has an on-chip oscillator but requires an external clock to run it
was something told to me.
I really did not get that point. 8051 has internal oscillator(well oscillator can produce oscillations) and then, why to use an external crystal for it??

 

[Genovator]

Re: to count pulses using 8051

Actually a crystal doesn't produces a square wave all by itself. It vibrates to produce pulses. It has a piezo electric effect, like a self oscillating buzzer. When an electric field is applied to it, it starts to vibrate. But that vibration isn't enough to drive a uC. The on-chip oscillator is required and it acts as an amplifier. Its nothing but just one or two NOT gates. It never oscillates itself. It requires an input and produces a pure square wave output.

**broken link removed**





P.s: One fact which many people doesn't know (maybe you know) is that the legacy 8051 core is not actually requires 12 clock cycle to execute 1 instruction. It requires 6 clocks. 12 clocks are feed from the crystal because just after the on-chip oscillator, there is a D-type flip flop (Divide by two) present. That initially divides the clock input to half. It is present because every uCs are sensitive to duty cycle of the clock. It can adversely affect the speed & performance of the system. So for getting a clock input of 50% duty cycle, this flip flop is present. In 89SXX series, there is a register by which you can bypass this flip flop and increase the system speed to double, but the reliability of clock source is on you.

 

[Disha Karnataki]

Re: to count pulses using 8051

It is present because every uCs are sensitive to duty cycle of the clock. It can adversely affect the speed & performance of the system.

ok...fine
u mean as the oscillator does not produce square wave meaning it produces rising or falling edges we need to have a flip flop which will convert the oscillators o/p to correct duty cycle which is nothing but gives proper high's & low's which represents a binary number..
right??

 

[Genovator]

Re: to count pulses using 8051

A crystal doesn't produces a square wave. But when feeded to the on-chip oscillator, the output becomes a square wave but with unknown duty cycle. Now to correct the duty cycle, it is passed through a flip flop.

 

[Disha Karnataki]

Re: to count pulses using 8051

i am doing a line follower. Circuit is working fine but, as i am using a 9v rechargeable battery,2 9vdc motor, 2 relays(operating range 9v-12v).
so,simultaneously i will be operating two relays,two motors as the bot moves so i found that 9v battery got discharged within 30min by operating one motor & one relay simultaneously then, what guarantee that it will remain for hours when two relays,two motors have to be operated..
so is there any other better way out?? can i place a solar panel above it & continuously charge it??

 

[Genovator]

How big & heavy is your total setup??? 9V motor will consume a lot of power. Why not to use cheap 3v motors, specially the one used in cassette players. They won't be heavy but delivers a good power. And try to avoid the relays also. Its coil resistance is low thus drains a lot of current.

 

[Disha Karnataki]

just a chassi with the two wheels and their respective motors with the circuit board having ldr's that's it.
actually i don't want to use h-bridge ic i,e lm239 then without relays how will i change the motor direction because it will move right and left then motor connections have to be reversed so, i will require relays.

 

[milan.rajik]

Use L293B to change motor direction. You don't need relay for motors.

 

[Genovator]

How you are running your chassis with just two wheels??? Other two wheels are passive???

 

[Disha Karnataki]

actually as you have suggested i have got two dc motors which can run on 3-6v supply these are NOT geared ones so i have to take minimum load that is why i will be placing just a battery on them and a small pcb board with the circuit on it. the pcb board itself forms the chassi for the line follower i am making a very tiny line follower.