DC micro motor control

[sfink06]

Hi all,
I am looking to design a PCB that can control 10 micro DC motors that run at 3 V and draw 60 mA. Should I be using surface mount H-bridges, and then control the inputs with a PIC? I had trouble finding anything that looked promising in limiting the size of the board. Thanks!

 

[birdman0_o]

Well, it wouldnt be an H bridge, because you have 10 motors, an H bridge is meant for four. Are the motors spinning at the same time? Independantly? And in one direction or two?

 

[sfink06]

All motors must be able to move in both directions, and at any given time up to 5 motors must run at the same time (it's for a robot.)

 

[birdman0_o]

ok, both directions would require a semi H bridge.
Which PIC do you plan on using? If you require speed control, this becomes a whole new level of difficulty...

 

[sfink06]

Some dsPIC30F2011 or something in that family, has the ADC channels I need for sensors, PWM, and 12 DI/O pins.

 

[sfink06]

Is it possible to have the h-bridge multiplexed, and then use the PWM channel to control the speed? The ADC input from the sensors will be able to determine how fast each motor needs to turn.

 

[birdman0_o]

By multiplexing the semi - H-bridge you are effectively making the max speed 10x less (divide by number of motors). How many PWM modules does your pic have?

 

[sfink06]

2 I think, the most I've seen In a pic is 8

 

[birdman0_o]

There are PWM driver chips, I dont know the names by heart.

 

[phoenox]

birdman what do you mean by semi - h-bridge?

I thought that an h-bridge was two high side switches and two low side switches connected to one motor.

 

[birdman0_o]

https://www.electro-tech-online.com/custompdfs/2009/11/SN754410.pdf
I should have said "half" instead of semi, sorry.

Actually I think I made a mistake, he would need a full H bridge

 

[Birdman Adam]

Ya a half H-bridge can control one motor in one direction, full is one motor in two directions. Maybe you could have one main PIC control 3-4 slave PICs with 2 PWMs each (two motors each driven by one SN754410). You would have to give each one an address and all of them would require a bunch of code though...

 

[Sceadwian]

birdman what are you talking about? In order to control a DC motor bidirectionally you need a full H-bridge.

 

[Birdman Adam]

Ya a half H-bridge can control one motor in one direction, full is one motor in two directions.

I'm assuming you were talking to the other birdman?
The IC shown at sparkfun has four half h-bridges in it. By connecting the motors and pins a little differently, you can make it 2 full (bidirectional) h-bridges instead.

 

[Sceadwian]

Lol! oh no there's two of you now!
Yeah, I was responding to birdmanO o

 

[colin55]

Don't forget, you can simplify things by having a spilt supply.

 

[sfink06]

thanks all, I think I'm just going to use 6 motors now, and only make one of them bi-directional (not really enough room on the robot for a PCB with multiple H-bridges.) If anyone knows some good small form factor H-bridge IC's, preferably SMD, I'd appreciate it.

 

[sfink06]

ALLEGRO MICROSYSTEMS|A3901SEJTR-T|Motor Driver IC | Newark.com

this looks promising, i think i can fit these on my board.

 

[jamesmatheson]

major companies have no idea what theyre selling , I keep asking for this https://photos.app.goo.gl/F3o8KCsIDwwKC47W2 and they keep asking for a parts number, I even paid $1000 to a company and they took the money and couldn't supply the product and now they posted my name everywhere on the internet and all the companies are asking for $1000 and more before I even tell them what I need,

 

[Ian Rogers]

Mega old thread... Locked now..