Author: Fishmahn

Stepper motors

Posted on by Fishmahn

I’m doing some work for a client.  He has a model railroad and wants to have a gantry crane he can operate with joysticks.  He purchased this thing called an Arduino and needs me to program it for him.

Ok, I look up Arduino and think ‘no problem.’  The language for an Arduino is similar in style to C, so I can deal with it.  He has 3 stepper motors, 3 ‘easy driver’ boards that control the motors, a joystick and an Arduino UNO to program it.

First thing we do is go through some tutorials, making an led light turn on, displaying the ambient temperature from a temp sensor and a few things like that.  Then we figure out the wiring required to run the stepper motor through the easy drivers.  It was late so he says he’ll solder them up and we can test next time.

Next time comes and the motors don’t move.  I check the wiring and it looks right. all the wires have continuity from board to board, I power everything up and the power lights work.  I used sample code from the easy driver designer’s website so that should work, but I get nothing.

So I check the specs on the motors.  3V, 1.7A, 400 steps/rotation.  I’m feeding it power via the usb port on the Arduino which means I’m only giving it 0.5A.  That’s the problem.  So i get a separate power supply and feed it up to 2A.  At this point I’m only testing 1 of the motors.

Still nothing.  It’s only drawing about 0.035A.  I check everything I can think of – make sure the motor is wired correctly, the boards are wired right, etc.  I even try the other boards in case one of them got blown somehow.

Nothing.

Ok, I sign up on an arduino forum, post a question and call it a night to wait for an answer.  The next day the client calls me and says to call this phone number and maybe the tech support people can help because that’s where he got the hardware from.  I call them up and the tech. points me to their custom support page for stepper motors and the easy driver board.  The instructions say to feed the motor at least 8V, but no more than 32V.  8V?  But I have a 3V motor.

I go to the client’s workshop, set the power supply to 9V, 2A and separate the power to the Arduino from the power to the motors because the Arduino needs 3.3v or 5v, not 9v and I don’t want to blow it.

I power everything up and the motor starts to move.  What?  That’s all it needed?  We wasted 3 hours because a 3V motor isn’t a 3V motor, it’s a 9V motor.  There’s got to be some logic there, but I can’t figure it out.

I adjust the potentiometer on the easy driver board until the motor runs smoothly and watch it go for a min.  Then it starts to miss.  So I turn up the power a little more and my fingertip briefly touches the chip that controls everything and OUCH!  That’s HOT!  I don’t mean a little warm, but blisteringly hot.  I swear the magic smoke is about ready to come out.  (I’ll tell you about the magic smoke in computers some other day).  I quick turn off the power and let it cool down a min.

I turn it back on and it runs smoothly, for 30 sec or so, then it starts missing again so I feel the chip again. Not as hot but getting hotter by the second.  Something’s not right.  I turn the pot down to the lowest setting that lets the motor run smoothly and it still starts missing after a min.  Yep, the chip is sizzling again.

I call the tech guy again and he says that the easy driver is only good to about 1.2A but there is a driver board that can take up to 3A.  Why did they sell a 1.2A board with a 1.7A stepper motor???  So the client orders the 3A boards and we’re waiting for them to arrive.

All that — a 3V motor that really needs 9V and the easy driver board can’t handle the amperage of the motor.  All in a day’s work, I’m sure but, “Aaaaaarrrrrrrgggggggghhhhhh!!!!!”

Hassenpfeffer

Posted on by Fishmahn

The dog got a rabbit. He was happy about it. Me, not so much.

 

I’ve got a smallish yard in the suburbs with a 4 ft chain link fence around the back – It’s only 50 ft wide but reasonably deep at over 150 ft. But, take the house, the front yard and the garage out of that, and the back yard space is about 50 x 80 less a cut-out for the garage on one side. We get regular wildlife – rabbits, lots of squirrels, the occasional opossum. Haven’t seen any skunks but I know they’re in the area.

 

Anyways, it was late evening – about 10pm and I went to let the dogs in. Yep, I have multiple dogs. Like a crazy cat lady you may ask? No. I have 3 dogs but only 2 of them are here at the moment. Casey is out of town with my wife. She trains school bus drivers and she’s at a bus company about 6 hours drive away for a couple months. When she came back for a weekend she picked up ‘her’ dog to come with her for company. Hopefully they’ll be back in a couple weeks.

 

About my dogs. First there’s Beowulf, we call him Wolfie. He’s a big dog, just my size. Telling you he weighs only 85 pounds doesn’t tell you how big he is though. He’s a cross between a German Shepherd Dog (GSD) and a Mastiff. He got the GSD’s body – skinny – with the Mastiff’s legs, long and large. The head is GSD-shaped, but wider muzzled with the excess skin around the jowls a Mastiff has. He’s almost 10 now, but when he was younger he could put his paws up on my shoulders and look me in the eyes. Oh, I’m 6 ft 3 in tall. He’s mostly black with beige and a bit of white on the chest & belly. Not the tan of most GSDs, but beige. Long furred like most GSDs. We got Wolfie when he was 6 mos. old from a guy who I don’t think was expecting as large of a dog as he got. So, he became ours.

 

Next we got Casey. Casey is a small dog. Well, small to me. She’s about 45 lbs, Pit Bull or Staffordshire Bull Terrier or some mix like that. A little small for a Pit but that class of dog. She’s cinnamon colored with a red nose. Yes, a red-nosed cinnamon Pit. One word of warning though, she’ll knock you over and lick you to death, and her tail will leave welts from all the wagging. And don’t let her get you started with a ball or tug. You won’t be allowed to leave. Seriously. She’s 6 but most people think she’s still a puppy because of her energy.

 

Lastly there’s Chance. Chance got his second chance with us (pun intended, that’s why he was named Chance). He’s a lab – something mix. Probably a Coonhound or some sort of Cur, I call him my hillbilly hound dog because he came from Kentucky. He’s a midsize dog at about 65 lbs. Brown, but not chocolate lab brown, more like the brown on a beagle or hound dog. He’s 4.

 

Meanwhile, I’m letting the 2 boys in and Chance rushes in like normal – he sees an open door he goes through it, even if that’s not where he wants to be. I have to call Wolfie. A couple times. Finally he comes trotting up… with a rabbit in his jaws. Yep, it’s dead. I think it’s his first rabbit. Well, first that I know of. He wants to bring it inside. Now I don’t have the cleanest house, I have dogs after all, and I don’t mop as often as I should, but a dead rabbit is not coming into my house. We have a bit of a conversation at the back door for a couple minutes before he gets the message that he has to drop the rabbit to come inside.

 

Now there’s blood on my concrete back step, under the awning where the rain won’t get to it. Knowing me that’ll be there for a while.

It Is time

Posted on by Fishmahn

It’s time for me to start making my presence known.  I don’t expect millions of people to read this but someday someone might.

I don’t usually have much to say, so this is difficult for me.

I make computers work.  I assist users.  I install networks.  I can show users how to use their software one on one.

I’ve extended that into smartphones and tablets because they’re just computers.  Computers just work for me.

Maybe it would be better to say that I can sense how a computer operates – and make the connection between non-computer users and their computer.  It takes a way of thinking to make them work because they’re not magic, just a bunch of electrical signals.