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1  Using Arduino / Project Guidance / Re: Arduino and a 17 servo motor robot, possible? on: July 18, 2014, 11:52:45 am
It looks like the servos used are like the dynamixel type where they are on a daisy chain bus with each servo having an I.D. and have the ability to respond and respond back via commands. Don't know if they copied the dynamixels ver batim .

The dynamixels have been used with an arduino but don't know about these though. Are they pretty new to the public?

Maybe a little "sniffing" program might pick off some info if the manufacturer is keeping a lid on the command structure.
2  Using Arduino / Motors, Mechanics, and Power / Re: 360 degree 30kgcm servo on: July 06, 2014, 05:59:03 pm
Be aware about driving a sail winch servo into it's extreme ranges. I did by using the "Knob" example in the IDE .

On my servo (now dropped by Pololu (I wonder why)) when the pot on the arduino was rotated towards the extreme ends the servo would act like a continuous one by never stopping. Once the pot was brought back to the center position the arm (actually a drum) on the servo was miss located a lot. The servo did not work very well after that. From what I saw after opening it up the plastic gear got a little chewed up. Pololu on the product page had a snippet about it. The servo's pot had end stops that let it rotate only about 190-200 degrees.
3  Topics / Robotics / Re: Entry Level Robotics: How to get started on: July 02, 2014, 12:20:31 pm
If you are in the states then Maker Shed has teamed up with Radio Shack to provide a robot using an arduino. It looks like the kit is meant to do a line following one but it can be altered into other types. Do not know how long the Shack will be around though.

I checked around and my local stores have it in stock. They also have a motor kit with some wheels too.

Just something to chew on.
4  Using Arduino / Project Guidance / Re: 4 brush-less DC motors with integrated drive electronics using an Arduino Uno on: July 02, 2014, 12:06:42 pm
My contact from Precision Micro-drives was kind enough to send me a drawing and a link to explain how he would do it using MOSFET, however I'm afraid this is out of my league and I'm in need of someone to explain how all the components are working and why etc.


Haven't we already established that the motors don't support pwm?

The datasheet does state that but in the performance graph the voltage varies between 1.6 and 3.6  to show it's characteristics.
In the drawing provided the signal into the mosfet  does infer it though. The OP did not provide the "link"  so can it?

I would be tempted to try if I had a few extra . What happens to it if you do pwm it?

Got a pot to do a simple  varying voltage setup?  Does it work? Control the pot with a servo or get a digital pot.

5  Using Arduino / General Electronics / Re: SPI Inline Switch Challenge on: July 01, 2014, 08:56:02 pm
Does each slave need it's own address (CS) on the SPI buss? That is does the master send out the data to each slave individually or do they receive the same data at the same time and each slave figures out what it has to do with the data by sorting it out?

Even though the SPI has that speed can the master actually process the needed data for all 3 slaves at that rate?

Maybe a benchmark on what the master can actually output.

As a side note the 328 can use it's usart hardware in spi  mode but that would require some rethinking  on another level.
6  Using Arduino / Displays / Re: More trouble with my LCD on: June 28, 2014, 07:12:24 pm
From your picture it looks like you do not have the R/W or the Enalble of the LCD hooked up.

Since you cannot read from the LCD  just tie the R/W pin(5) to ground.

The Enable is used as a strobe to read the data lines. Somewhere in the documentation of the software you are using should show how all the pins are hooked up.
7  Using Arduino / Motors, Mechanics, and Power / Re: GBRL with custom function on: June 28, 2014, 01:03:41 pm
If you are only using 2 steppers with GRBL then maybe use the Z axis drive pins to control the 2 relays.

The direction pin could be used to select which relay to activate ( a little bit of logic) and the step pulse to activate the desired relay. Move Z plus for one and move Z minus for the other. Just need to play with the amounts to move the Z axis (maybe might need to play with # of steps per m.m. in the GRBL settings for the Z axis)  to figure timing of ON time for the relay.

The step pin of course would need to be run thru a rc filter to filter out the pulses but once the move is done then the pin goes low.

Just one way to do it without doing any software changes.
8  Using Arduino / Microcontrollers / Re: Analog Inputs/Outputs with ATTiny 84 on: June 20, 2014, 01:52:15 pm
Sure go ahead and take my words out of context but I'm just trying to learn you. smiley-twist

Simple coding in the world of the arduino does not require someone to fully understand the inner workings (gee like how does the pin create an output that can control something  with a varying voltage). If one wants to know then nothing is stopping them to do so. But to make someone at the very beginning to understand how it is done is not what  was intended.

As for yourself if you are so easily confused then maybe  it's time to teach something else.  smiley-evil

9  Using Arduino / Microcontrollers / Re: Analog Inputs/Outputs with ATTiny 84 on: June 20, 2014, 12:13:03 pm

Be aware that only the pins marked as pwm can be used as analog out.

Pwm its not analog , its digital..

" Pulse Width Modulation, or PWM, is a technique for getting analog results with digital means "

I am very well aware of that(been an avrfreak since 2003)  but to respond to someone that is new to the arduino world one should not confuse them with the details since the command to utilize pwm is called analogWrite and not digitalWrite or pwmWrite. The arduino was created for people (artists for one) that just wanted to get something to happen and not worry about how it was getting done  if you were not aware of that.
For the OP since this required some fancy maneuvers to get the program onto the ATTINY84  have you at least been able to do the basic "Hello World" program of blinking an led at a certain rate?
10  Using Arduino / Microcontrollers / Re: Analog Inputs/Outputs with ATTiny 84 on: June 19, 2014, 08:51:36 pm
Have a look at this chart to help you in "mapping" your pins to the correct physical pins of your tiny84.

Be aware that only the pins marked as pwm can be used as analog out.

11  Using Arduino / Displays / Re: Dead LCD Display? on: June 18, 2014, 04:52:09 pm
Well you have your contrast pin (pin3 of the lcd) tied to the +5 thru a 10k resistor. Should have a pot (5-10k ) connected to the +5 and ground with the wiper(middle pin)  going to pin3. For a get around just tie pin3 to ground  which will give maximum contrast (black boxes before the program tries to initialize it).
12  Using Arduino / Motors, Mechanics, and Power / Re: Servos keep damaging on: June 15, 2014, 12:38:29 pm
So from what I've read the only servo that gets damaged is the one that activates the "Claw" part of the robotic arm?

How are you wiring up your regulators? Did you just wire them up with no capacitors?

For that regulator the Min input voltage is 8.0 . Maybe just a couple of inline diodes(with the proper amp rating) to drop it down would suffice.

As for the resistor idea I have played around with that and for my servo it ran OK and with a 20 ohm at 5 volt  it drew .1 amp when I kept it from moving and it still had some pretty good holding force.
13  Using Arduino / Motors, Mechanics, and Power / Re: How to stop a servo on: June 11, 2014, 06:41:54 pm
Well I had to give it a try (resistor inline on the power line) so I loaded up the "Knob" sketch and using a Hitec HS-310 servo I tried some various resistors. It didn't like the 100 ohm (wouldn't budge)but it did OK on the 10 ohm and I could stop it but the pressure was a little too much (I'd say about half of what it would normally be) so I tried 20 ohm and that seemed to do a good job of putting enough pressure  and left alone it sweeps like normal. No twitching or signs the servo was not liking it.

But with a micro servo (don't have one) or true digital (ditto) things might be a little different. Just had to find out that's all.
14  Using Arduino / Project Guidance / Re: stepper motor takes a lot of pins on: June 10, 2014, 08:48:44 pm
The A4988 is a Bipolar driver whereas the stepper you have is a unipolar (5 wire not 6 wire)stepper so that getting the A4988  for your stepper would be like getting  a hammer to do your nails (on your hand).
15  Using Arduino / Motors, Mechanics, and Power / Re: How to stop a servo on: June 10, 2014, 05:17:49 pm
Just thinking that (have never tried it) a resistor inline on the power line into the servo might limit the amount of force exerted.

Mechanically back in the old days and maybe now too would be to use something called a "servo saver".
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