connecting relay output to PIC16f877a

[eng.msmahmoud]

Dear all


am using the following module as TX-RX remote control, i need your help in connecting the output of the relays to the microcontrolling to implmnet my algorithm

after some searching i got that i may connect this output directly to the micro-controller, but i cannot understand what is meant by rely stat :
A pin is close
B pin is opne and close
C pin is open

**broken link removed**

 

[pjmelect]

I guess that what they mean is that "A pin is closed" (unenergized) normally closed contact of the relay.
"B pin is open and close" is the common connection of the relay or pole of the relay.
"C pin is open" (unenergized) normally open contact of the relay

 

[eng.msmahmoud]

but when i connect 12v dc i got nothing !from three pins

 

[pjmelect]

The three pins will be isolated from the 12 V With a Ohm meter check if you have continuity between pin A and B with the unit off, and then check for continuity with the relay energized.

 

[eng.msmahmoud]

i did so , when unit of A and B connected and when device is on C and B connected

so what is the connections should be with micro-controller pins ?

 

[Joeisi]

You cannot directly drive a 12v relay with a 5v micro. You need more power. You will need to put some transistors in between the F877a and the relay.