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Open DAVID-hardware project

Re: Open DAVID-hardware project

Postby fz1 » Sat Feb 21, 2009 1:27 am

Since most here are going to try the Arduino I ordered mine last week and I came today.
First testing the board out it works. Now I have to do some more with it to learn how to drive the steppers. I also bought 2 easydriverv3 boards but I think I will need a different board for the steppers.
Still following this and other threads on the control setup.
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Re: Open DAVID-hardware project

Postby MagWeb » Sat Feb 21, 2009 8:50 am

Hi ,

for I shot down the bootloader on my Arduino yesterday:

There might be still a mistake in the circuit shown in the Wiki (the parts that drive the Cree LED and the voltage reduction to 3.3V are not tested yet).

To upload the bootloader again, I`ve to tinker a parallel adapter :roll:

Gunter
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Re: Open DAVID-hardware project

Postby WalterMo » Sat Feb 21, 2009 4:49 pm

Gunter,

Any problems with the circuit?
In the Wiki you have equipped the gate of the power MOS fet and the gates of the two BS170 with a resistor of 1 Ohm. It will work but better are 1kOhm resistors as I suggested. These resistors should protect the Arduino outputs in the case of a short cicuit.
For first tests of the switched laser you should use a resistor of about 18Ohm or the back light (6V/0.6W) of a bicycle instead of the laser.

Walter
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Re: Open DAVID-hardware project

Postby MagWeb » Sat Feb 21, 2009 6:04 pm

Hi Walter,

sorry, for the mistake forgetting the K in the diagram :oops: but I built it on my breadboard with 1Kohm. :) (diagram corrected)

It seems to me that I somehow mistook some wire....12 V polarity ...:x I was playing around with the already tested partial circuits of the buttons and steppers....The new parts were not active.

Until now I didn´t succeed getting the ATmega back to work and maybe it crossed Jordan, but on the other hand I learned how to convert a Arduino into a AVR writer http://www.geocities.jp/arduino_diecimila/bootloader/index_en.html

Seems I provocated this accident ordering a second Arduino before. Thanks for the tip concerning the laser. I thought using my old terrible "line"-laser from Lidl to do the tests.

Gunter
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Re: Open DAVID-hardware project

Postby MagWeb » Sun Feb 22, 2009 6:59 pm

Hi,

got the ATmega168 back to work using the way as linked in my previous post. Works perfect (if you don´t place the chip the other way around into its socket :oops: ).

With the new bootloader Arduino works as being a new one :P

On we go

Gunter
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Re: Open DAVID-hardware project

Postby MagWeb » Sun Feb 22, 2009 10:03 pm

Hi,

after getting all to work again, I assembled a proto-shield for the Arduino( simply underneath the visible board) plugged onto via the Arduino pins.
There´s still a lot to be done. I tried this design to check out whether it might be possible to pack all needed components on a single plug onto shield.

Didn´t check the output for the Cree LED yet, and somehow the laser gets permanently , but nice reduced power (maybe something to be changed in the code of the sketch). Still there are missing additional heatsinks ...

On the breadboard remained only components that are planed to be somewhere else in the setup (motors, buttons, laser and sometimes the Cree)

Any suggestions?

just to report
Gunter
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Re: Open DAVID-hardware project

Postby MagWeb » Thu Feb 26, 2009 10:54 pm

Hello,

The board and its circuit works. Perfect Communication via COM using 2.3.

I removed the LM317T from the board. As Walter predicted, it has to radiate some heat. You might burn your fingers! The heatsink should have some size. So I decided to keep the output as a MosFet switched 12V output. So you can decide which light you want to use. Cold kathode lamp, LED ....
The different electronics needed by these lightsources should be added to the lamp itself.

Contact me to get the board layout or Eagle files.
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Re: Open DAVID-hardware project

Postby Bongobat » Wed Mar 04, 2009 4:36 pm

Hi,

Well I have just placed my order for the easydriver, the atmega168 preprogramed with aurduino bootloader a max232 and a crystal. I really wanted to breadboard the entire thing even the easydriver but seems the individual chips are hard to find. I went with db9 serial communication because I already have the usb232 adaptor and although the ftdi usb to ttl chip is quite cheap I could not find it in any form but smd. Yes smds are hand solderable but tricky and for now I am keeping this very simple. I am also going to try to add an l293d as a turntable stepper driver. Turns out the site Sparkfun that Gunter has mentioned has pretty much everything you need for this and after some further digging around their site I found this: http://www.sparkfun.com/commerce/tutori ... ials_id=57 A very good resource :!:

So I will let you all know how it goes building it from scratch. :wink:

Greg
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Re: Open DAVID-hardware project

Postby RAYA » Wed Mar 04, 2009 5:34 pm

Hi Greg

Why you don`t use FT232RL to connect directly to usb with atmega 168 as in Ardinuo say.

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Re: Open DAVID-hardware project

Postby Bongobat » Thu Mar 05, 2009 3:36 am

Hi Raya,

I am ordering all my stuff from sparkfun to save on shipping and they do have that chip but looks like only as an smd : http://www.sparkfun.com/commerce/produc ... cts_id=650. I could be wrong but I think smds are not easy to breadboard. I could have gotten the breakout board:
http://www.sparkfun.com/commerce/produc ... ts_id=8772 but that raises the price. Since I already have a USB converter I figured this would be best to have a serial interface and when I am not using the arduino I can use the converter for other things

Greg
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Re: Open DAVID-hardware project

Postby Bongobat » Tue Mar 10, 2009 4:55 pm

Hi,

Yesterday I successfully completed the serial arduino on a breadboard and uploaded the blink sketch to it. :D Before I add the easystepper though I want to make a stepper driver based on the l293d like this: http://arduino.cc/en/Reference/StepperBipolarCircuit

I was wondering if I need optocouplers to isolate the output pins of the arduino from the stepper chip or is it safe to just go by this schematic?

Thanks,

Greg
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Re: Open DAVID-hardware project

Postby joecnc2006 » Tue Mar 10, 2009 5:53 pm

Here is what allot of people build for the DIY CNC machines. plenty of designs already if you like to use one of them, plus you can do a board etch and have a nice driver board. Use with a Breakout board and control the laser as well as a turn table. Also use a relay on the BOB to control laser on and off.

http://pminmo.com/
Joe

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Re: Open DAVID-hardware project

Postby WalterMo » Tue Mar 10, 2009 10:21 pm

Hi Greg,
I think you don't have to use optocouplers to isolate the Arduino galvanically from the L293D.
Important is to pay attention of the ground line of the motor power supply and the ground line between Arduino and motor driver IC.
That means the 0V of the motor power supply has to go directly to the 4 Gnd pins of the L293D.
The 5V of the driver IC and the 5V of the Arduino can come out of the same voltage source.

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Re: Open DAVID-hardware project

Postby Bongobat » Fri Mar 20, 2009 6:18 pm

Thanks Walter that is good news.

I have been busy trying to program the arduino for the easystepper but was wondering if anyone knows how to program microstepping for the l293d. I read somewhere it can be done with pwm but I havent found a good explination.

thanks,
Greg
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Re: Open DAVID-hardware project

Postby WalterMo » Fri Mar 20, 2009 9:18 pm

Hi Greg,
Why do you try to use the L293D when you have the ready EasyDriver?
Pulse width modulation is a not very simple technique and requires some more additional ICs. I have never seen a circuit diagram with pwm in conjunction with a stepper driver.
If the output current of the EasyDriver with its 8 microsteps isn't sufficient you can find other powerful microstepping ICs on the market, e.g. the TB6560HQ, the IMT-901 or the TA8435HQ.
Some time ago I have used the IMT-901.

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