i'm a beginner and doing my project now...
when i was testing my project...i found that...
the PIC16F877A will reset always when the DC motor running...
after i checked...
i knew it is back emf matter..
but i have find no way to solve it...
is it anybody can help me to solve it?????
PLS!!!

Thanks Regard...

 

thanks Alberto
i had seperate the power supply..
actually, i had tried to test 1 part by 1 part.
mean i had try my programming and DC motor with relay separately...
when i was combine these 2 circuit...
the DC motor is no working and the LED on PIC circuit is lighting randomly...
and i had tried adding diode series with resistor...
still cannot working...

 

Sounds like a noise issue. try using a reverse biased diode on the motor maybe? Or even stabilising the PSU more.

Matt

 

thanks Matt...
sorry for i'm a beginner and i don't understand what is PSU mean?
can you explain for it?
thank for regard...

 

Sound the current of pic not enough to accurate the relay may you need to connect transistor like 2N3904 to relay

 

the circuit diagram i had put in "relay.doc" file...
all your help is really appriciated...
thanks regard...

 

Are the grounds really separate for the two supplies?

 

ground for both supply v1 and v2 shuold be connected otherwise transister will not pass the current to start relay

 

Also there is some things missing in the circuit like relays doesn't have ground.

Circuit need to be redrawing again

Tell me what is your project and I can help you in redraw it again

 

thanks for reply by everyone...
i'm really appreciate all your helps...
act i forgot to draw the link between ground of v1 and v2...
i had connected together when i was testing...
the problem is the that when switching ON the PIC and motor...
both of PIC and motor will runnning 1 or 2 secs then PIC reset...
act my project is like an Automatically Guilded Vehicle...
i need to make the car move automatically and it shud avoid obstacle...
i already done the IR sensor and porgramming part...
the most headache is the back emf of motor...
cos the motor will create back emf while it is running...
therefore, it will affect PIC and make it reset...
and that is the problem i need to solve...
thanks for regard...
i'm really appreciate any help from you all...
thanks...

 

1) You didn't say if the reset pin has been pulledup with a 10 k resistor.

2) Change connection to relays as per the attached schematic.

3) From your schematic it seems that pic ground is isolated from relays ground.

NPN transistors to conduct need grounds to be in common, connect the two grounds together.

Alberto

thanks Alberto...
i had tested the circuit...
the relay can run well when i test single part...
but the result is same when combined with PIC...
the PIC is keeping reset...

 

Hi !!
You look out when drawing board, Groud of Pic need connect directly to Groud source.

 

thanks vdtk3...
i will get another try on this...
hehe...