How to control dc motors with the use of H-bridge ?

[kotsam]

h-bridge,

i'm programing pic16f877 to control two dc motors by using h-bridge.... and i've problem because i can't reverse the motor. i connect the direction pin,and i send 1 or 0, when it's 0 the motor should reverse but i don't know why it's not reversing
i'm using lmd18200, so if anyone can please tell me how to directed or to write for me the essential instruction of this operation.


thanks very much

 

[leomecma]

Re: h-bridge,

Have you measured if that pin is going to low and high level? What exactly doesn't work PIC or your bridge driver?


leomecma

 

[kotsam]

h-bridge,

i did small test for the h-bridge, i connect switch with 5 volts going to the direction pin and 12 volts as normal to the h-bridge Vs when i apply 5 volts to the direction the motor goes clockwise but when i apply 0 nothing happened ...maybe this test wrong ...?if u have another way to test the h-bridge i would like to hear..
thanks

 

[leomecma]

Re: h-bridge,

If you are applying zero volts, and you aren't using break pin it has to work. But just a question: How are you giving 0 volts? Are you connecting it to ground or just floating? Floating doesn't work ....


leomecma

 

[Ahmed Ragab]

Re: h-bridge,

Hi,
Your complain is quite weird, I've worked with an h-bridge before and it's just sweet and simple.
You said you send a 1 or a 0 to the direction pin, so I will exclude the possibility lecmocema has just suggested of the floating pin.
Most probably you got something wrong in your connections or else your h-bridge will be faulty.
Upload the diagram and your code if possible and I'll do my best to help

Salam

 

[Tohu]

Re: h-bridge,

Hi,
In first place, try controll the chip directly, without MCU, only connect Breke pin to GND, PWM pin to + and switch direction between ground and +, but power supply must be below 12 V, this is a maximum for logic 1. If the motor change direction then problem is in your MCU level.
If your DC mottor have a stator, then is very possible that this is the problem, when you have stator and rotor, always you will have only one spin direction, if you want to change must change stator OR rotor polarity. But you can use multimeter to see the change of polarity or two parallel LED with different direction.