Motor Control

[threewheeler7]

I am working on a h-bridge motor controller, driven from a uC. the uC sends two lines for direction and has a PWM output. now, i have the controller running for what i need, but i need a good h-bridge, i have a few ta72915 SIP bridge drivers, depending on how easily i can find more, these may be what i use in my final design, if not, it will be something close. but for now, i will be using this chip just because i have it. basically i need to know, how i run this PWM'ed. ie. where dose my PWM line from my uC go? i have included 2 screen shots from the data sheet, the pin descriptions, and the sample circuit.

 

[ericgibbs]

I am working on a h-bridge motor controller, driven from a uC. the uC sends two lines for direction and has a PWM output. now, i have the controller running for what i need, but i need a good h-bridge, i have a few ta72915 SIP bridge drivers, depending on how easily i can find more, these may be what i use in my final design, if not, it will be something close. but for now, i will be using this chip just because i have it. basically i need to know, how i run this PWM'ed. ie. where dose my PWM line from my uC go? i have included 2 screen shots from the data sheet, the pin descriptions, and the sample circuit.

hi,

Which MCU type are you using.?

 

[threewheeler7]

hey eric, nice name (thats my name too), i am using a PIC. but why does that matter? just curious.

 

[ericgibbs]

hey eric, nice name (thats my name too), i am using a PIC. but why does that matter? just curious.

hi,
Just trying to get an handle what you are trying to do.

I have found that giving answers without context can get confusing.

Usually its just the PWM IN1/2 pins [2] to the H-Bridge inputs as per your dwg.

EDIT:
Just downloaded the datasheet, will have a look.

 

[threewheeler7]

hi,

Usually its just the PWM IN1/2 pins [2] to the H-Bridge inputs as per your dwg.

what do you mean by that? i just have two control lines going from uC to h-bridge. 10= cw 01= ccw. to add PWM i need to take my PWM output and connect it somehow to the motor driver. i am happy to give you as much info as you need. anything else?

 

[ericgibbs]

what do you mean by that? i just have two control lines going from uC to h-bridge. 10= cw 01= ccw. to add PWM i need to take my PWM output and connect it somehow to the motor driver. i am happy to give you as much info as you need. anything else?

hi,
Basically you drive the IN1/2 pins with the PWM drive, this can give speed and direction control.
Why would you need 2 pins for direction only.?

**broken link removed**


EDIT:
Use the SEARCH option on the forum for: H Bridge there are lots of threads with advice that should help.

 

[threewheeler7]

i am sorry, i am using hardware PWM. i need direction only pins and PWM separate.

 

[ericgibbs]

i am sorry, i am using hardware PWM. i need direction only pins and PWM separate.

I would think in that case, extra logic gates, say 2 off, two input AND gates would enable you to choose direction and PWM.

Do you follow OK.?

EDIT:
Something like this.

 

[threewheeler7]

yes i do follow, but your saying that there is no separate input for some sort of reference or PWM on the controller? than can you think of any way to keep component count down and still use hardware PWM?

 

[threewheeler7]

i didnt post this in the wrong place did i? because i am really sorry if i did.

 

[ericgibbs]

i didnt post this in the wrong place did i? because i am really sorry if i did.

hi,
I suppose the 'micro controller' forum would have been the best place.
Sundays can be a litte quiet, I'm sure others will give you input.

As you want to keep the component count down, is it possible to rework your PIC program so that you can drive both the IN1/2 with PWM.?

Are you in the UK.?

 

[threewheeler7]

hi,

As you want to keep the component count down, is it possible to rework your PIC program so that you can drive both the IN1/2 with PWM.?

Are you in the UK.?

no it is not posable to do that with hardware, and i need all the software room i can get. cant the PWM go to the Vref input?

no i am not in the UK. why?

 

[threewheeler7]

never mind i answered my own question. if i am driving the motor @5v i can just send PWM to Vref. if higher voltage is needed i can just run PWM through a current limiting resistor to the base of a transistor to switch a higher voltage.

 

[ericgibbs]

no it is not posable to do that with hardware, and i need all the software room i can get. cant the PWM go to the Vref input?

no i am not in the UK. why?

The Vref is used to set the motor voltage, if not used its connected to the +Vsupply.

It sometimes helps if we know the posters location.