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Arduinos and Microcontrollers ref: Rotary Table Mew 249

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Dave Daniels13/12/2016 10:04:13
82 forum posts

As an aside to this 'LCD no werky' thing, if you get an 'X-Temp' or extended temperature range device, the bottom end of the contrast pot. has to go to a negative voltage not to 0V as usual. I don't know if this pertains to ALL X-Temp displays but did to 4 I was given.

I've been in that hole, and it ain't at all obvious until a severe shufti at the data sheet reveals the pot. goes to -V ...angry not 0V.

Can be a -5V derived from the +5V using a ICL7660 chip yes

Just a thought ..

 

D.

 

 

 

 

Edited By Dave Daniels on 13/12/2016 10:05:20

Edited By Dave Daniels on 13/12/2016 10:05:38

Carl Wilson 413/12/2016 11:32:38
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670 forum posts
53 photos
It's a good job we have this forum.

As the primary objective of any magazine is to sell copy, it is impossible to include all this esoteric information in an article.

This is what the Internet is for. This and porn, obviously.
john swift 113/12/2016 11:42:33
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318 forum posts
183 photos

now I have an Arduino uno clone and I picked up a LCD sheild yesterday

I can update the diagram for a PWM compatable LCD sheild and possible veroboard DIY sheild

I need to double check which arduino pins are used for the stepper driver

I thought digital outputs 0 & 1  are used for step & direction but I can't find the expected step pulses when I jog or run

 

shd_1602v2 from  linksprite  =maplin code n07dh.jpgpwm brightnes mod lcdkeypad_shield_maplin.jpg

note - on this sheild the 10K between pin D10 and the transistor base prevents damage to the Arduino

 

I have confirmed 3 out of the 4 UNO terminal line up with the 0.1" grid of veroboard / perf board

using the long pin Stackable Header Connector sold for the arduino

the offset of J2 (D8 to D13 , gnd & ref) is small enough to bend the pins to fit int the Arduino socket

 

diy uno veroboard shield updated.jpg

John

Edited By john swift 1 on 13/12/2016 11:44:24

Carl Wilson 413/12/2016 20:02:39
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670 forum posts
53 photos
I'm not at all sure what benefit this arrangement is giving you. Can you enlighten me please?
john swift 113/12/2016 21:29:50
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318 forum posts
183 photos

Hi Carl

only having the Arduino and LCD shield a day your rotary table control is the 3rd program I have tried

and it works although I need to find the step and direction outputs

( the first being the blink & fade examples that come withe the arduino ! )

some my web searches for the arduino highlighted the issue with some LCD shields if you attempt to use PWM brightness control

(while its not an issue with your project now but it can be when an astromomer adapts it to control a telescope drive )

with a box of general purpose matrix boards

it makes sense to me to use a mixture of matrix boards I have and arduino shields

I need to look closer for the step & direction outputs are they output pins D0 & D1 ?

are the outputs open collector and need pullup resistors to test without connection to a stepper driver ?

John

Carl Wilson 413/12/2016 22:27:43
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670 forum posts
53 photos
Hi John,

I get it now. Step is pin 2. Dir is pin 3. Enable is pin 11. This non sequential leap is due to the other pins being used for the Lcd interface.

The outputs go low to pull down the corresponding inputs on the stepper driver. So you'll need pull up resistors but you are then looking for a low condition when the output is "on".

Love the Nipkow discs and Televisor btw.
Carl Wilson 413/12/2016 22:28:57
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670 forum posts
53 photos
BTW it's not my software it was written by Gary Liming.

Carl.
SillyOldDuffer14/12/2016 09:59:51
Moderator
7897 forum posts
1725 photos
Posted by Carl Wilson 4 on 13/12/2016 22:27:43:
Hi John,

...

The outputs go low to pull down the corresponding inputs on the stepper driver. So you'll need pull up resistors but you are then looking for a low condition when the output is "on".
...

I think Carl's answer is upside down. (It's a mistake I often make!) Shoot me if I'm wrong:

  • Digital Pin 2 (STEP) is normally low and pulses high to step the motor.
  • Digital Pin 11 enables the motor and is always high.
  • Digital Pin 3 (MOTOR DIRECTION) is normally low. It outputs a single high pulse to reverse the motor.

It's possible to code the Arduino to enable built-in pull resistors if you want to invert the switching logic.

Dave

Muzzer14/12/2016 10:46:45
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2904 forum posts
448 photos

I see that Siemens has developed an "Industrial IOT Intelligent Gateway" that will accept Arduino code and shields. There are 2 models priced at £74 and £160, depending on the features. The aim is to allow hobby and "new engineers" to be able to apply their work to more industrial environments.

Runs a 400MHz Intel Quark (x86) and can support a host of languages (Arduino, Python, C++, Linux etc) and talk comms such as Profinet, modbus etc. Takes mPCIe cards as well as shields, so plenty of IO options.

Cries of horror from some quarters no doubt. Echos of the Bedroom Basic events of the 1980s? But could be quite useful for housing and interfacing Arduino projects for use in real world environments.

Interesting...

mgnbuk14/12/2016 11:33:46
1094 forum posts
70 photos

Siemens No need to swear !

Cries of horror from some quarters no doubt. Cries of anguish more like

Interesting... as in "May you live in interesting times" in my experience.

Nigel B

Engine Builder14/12/2016 12:11:07
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243 forum posts

More confusion!

Fig.7 in the magazine article and also on the Liming PDF show the digital output pin location with pin 11 next to pin 3. On the Arduino board. It is pin 4 that is next to 3.

There is some comment in the read me file on the liming PDF that the code was changed from pin 4 to pin 11 and that no change is needed in the wiring.

I don't pretend to understand the code, I am a model engineer , not a programmer, but the code still refers to pin 11 motorEnablepin.

Could anyone explain please.

Les Jones 114/12/2016 12:12:13
2241 forum posts
153 photos

Hi Muzzer,
The ESP8266 modules are a cheap way to connect into your WiFi network and they can be programmed using the Aduino IDE.

Les.

Edited By Les Jones 1 on 14/12/2016 12:12:34

Andy Holdaway14/12/2016 16:49:38
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167 forum posts
15 photos

Engine Builder - You're right that pin 4 is next to pin 3 on the Arduino board, but once the LCD/Keypad shield is added the pins run 3, 4, 11 etc. The LCD uses the missing pins so they are not available on the shield.

Andy

Engine Builder15/12/2016 11:55:17
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243 forum posts

The motor arrived today and as I had the rest of the parts wired up ready the indexer was running in minutes.

Thank you to all the members that offered advice.

I am going to couple up the motor to my spin indexer with a 6:1 toothed belt drive.

To test the system I changed the sketch for a 1:1 ratio and selected 8 microsteps.

Very pleased.

If anyone is interested the motor I chose was this one **LINK** £23.00 including delivery.

SillyOldDuffer15/12/2016 14:06:11
Moderator
7897 forum posts
1725 photos
Posted by Engine Builder on 15/12/2016 11:55:17:

...

If anyone is interested the motor I chose was this one **LINK** £23.00 including delivery.

Very many thanks for that link! My efforts to drive a motor with this came to an abrupt end when I discovered that my carefully stored 'step-motor' was no such thing. The suitable motor I found online is over £30 plus postage, which was a bit more than I want to spend on an experiment.

One thing I have noticed is that you don't appear to be able to stop the indexer if you accidentally trigger the step function with silly values unless you reset it.

John Stevenson's comment about the undesirability of nested menus on this type of project has started me thinking: an friendlier interface shouldn't be rocket science, if only I had more time...

Off to order a motor now.

Thanks,

Dave

Carl Wilson 416/12/2016 00:17:30
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670 forum posts
53 photos

I'm glad to hear that everyone is getting along well with the stepper stuff.

I'm currently looking at doing a better user interface using labview. I don't write programs any more, I draw them.

john swift 116/12/2016 01:19:09
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318 forum posts
183 photos

'Hi Carl

Your the first to comment about my avatar televisor and Nipkow disc

( Nipkow disc patented in 1884 by Paul Gottlieb Nipkow )

Today I proved , just using the step and direction signals to control a stepper motor driver and motor every thing works as expected

I see no point connecting the drivers -enable to the arduino digital output pin 11 when its always high and enables the drive

the driver enable is a negative logic input - no input = drive enabled !!

John

john swift 116/12/2016 01:19:58
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318 forum posts
183 photos

part 2

I have just had a quick look at changing the code to use as the enable pin 4

as it is now it disables the motor at the wrong time

when I changed the enable setup it produced an error -

at 01:05 - its probably me

I'll have to see it as an opportunity to learn more about programming the arduino laugh

John

Carl Wilson 416/12/2016 03:46:35
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670 forum posts
53 photos

Fair point.

I immediately recognised your Nipkow discs and televisor. As a child I was obsessed with Logie-Bairds mechanical television system. I tried on several occasions to repeat his experiments, all unsuccessful.

Carl.

Journeyman26/01/2017 17:09:21
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1108 forum posts
219 photos

Well I finally got my version up and running.

rotab1.jpg

All seems to work step and direction wise but there is a lot of vibration when the motor runs. It also seems to have a sort of two vibration mode, it start quietly for the first part of an action and then vibrates like mad for the second half. Seems to be the same for long or short runs. i.e. if set to turn 5deg the first 2 will be quiet(ish) and the final 3 will try and vibrate it off the bench. If set to 30deg same sort of thing.

Also likes one way better than the other but I think that is just down to the worm engagement. The switches also need de-bouncing a bit more, have tweaked some of the parameters in the sketch but not quite sure if that is the right way? Still at least it functions.

I was thinking of putting my build version, duly acredited of course, on my web-site. Any problems with that?

John

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