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.RC.
21st Nov 2015, 08:11 PM
After a year and a half of procrastinating today I have finally lashed out and bought two scales from Singapore to fit to the 10EE. Since the price of the readers is so high I have decided to go the android DRO route. A year or so ago I bought some MSP430 launchpad kits for a good price.

I need to get an android tablet and some other components.

Any ideas of good cheap android tablets?

Android DRO Project | Yuriy's Toys (http://www.yuriystoys.com/p/android-dro.html)

sacc51
21st Nov 2015, 11:23 PM
A question on DROs, either android compatible or those with a remote, wired readout, do they require a coolant shield or doesn't coolant affect them?

jhovel
22nd Nov 2015, 02:25 AM
Hi Richard.
Any cheap Android pad will do, but make SURE that it has Bluetooth (some advertise Bluetooth and it actually doesn't - I found out by experience....).

Oldneweng
22nd Nov 2015, 07:43 AM
A question on DROs, either android compatible or those with a remote, wired readout, do they require a coolant shield or doesn't coolant affect them?

It is my understanding that they all need a shield, not only for coolant, but for chips as well. Anything on the scale will try to enter the read head and there is only so much a seal can protect against. I have a cheaper individual read head type DRO on my mill. I had covers folded from 1.6mm sheet to cover the max length possible and down below the bottom of the read head.

Every installation I have seen on the forum or YouTube has had covers.

Dean

.RC.
22nd Nov 2015, 08:32 AM
Hi Richard.
Any cheap Android pad will do, but make SURE that it has Bluetooth (some advertise Bluetooth and it actually doesn't - I found out by experience....).

Thanks Joe, I wonder about these cheap ones, take no notice of the rrp, I see people have bought them for as low as $19.

PendoPad 7" - Quad Core - Black - PNDP5M7BLK - PendoPads with Google Play - Tablet - Pendo


(http://www.pendo.com.au/pendopad/pendopads-google-play/pendopad-7-quad-core-black-pndp5m7blk/)

Vernonv
22nd Nov 2015, 08:52 AM
I'm using TouchDRO on a old Windows tablet that I installed Android x86 on. It works well, but I had to use an external Bt adapter.

I just recently bought a second hand PendoPad 7, and although I can pair the Bt, I can't seem to get TouchDRO to connect. Still working on a solution.

All my DRO gear is Arduino based ... I have bought Uno's for $5 each and Nano's for $3 ... bloody cheap.

Vernonv
24th Nov 2015, 07:03 AM
Just an update on this .... Yuri posted a new version of TouchDRO on his website (don't know if it's on Google Play yet) which seems to have fixed my Bt connection issues with the Pendo Pad 7.

Just waiting on the scales to come in so that I can setup the DRO on my lathe.

Piers037
25th Nov 2015, 07:08 PM
I have finally lashed out and bought two scales from Singapore

Hi RC,

what type of scales did you go for? And which supplier did you use? I am looking at some Ditron glass scales for a touch DRO project for my Maho mill and will watch this tread keenly.

I will start off using my android phone as the screen.

Cheers

Piers

.RC.
25th Nov 2015, 08:44 PM
I went with the normal 5um scales, but the one for the cross slide is a slim line one. I purchased them from the DRO store, which I think used to be Meister. I have purchased from them before. They ship by fedex and are on their way.

I did not actually know aliexpress sold DRO units as I would have searched there as well for a set, having a look prices seem to vary wildly but brand name ones like Easson and Sino seem to be slightly cheaper then what they sell for at the DRO store.

My Pendopad turned up today. It is an older one without bluetooth capability. I plan to try to run it off a mains powerpack without the battery and connect the launchpad to the tablet with the USB cord.

I am under no illusion that in the long long term it is probably not cheaper then a dedicated proper reader unit as they should last decades, but I do struggle to understand why the proper readers are so expensive these days.

Shop glass scales 5um online Gallery - Buy glass scales 5um for unbeatable low prices on AliExpress.com (http://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20151125013415&isPremium=y&SearchText=glass+scales+5um)

Piers037
25th Nov 2015, 09:05 PM
I am looking at these scales.

Cheers

Piers

(Package Sales) 3 pcs of Linear glass scale/encoder/ruler DC11 measuring length form 50mm 500mm(1um)-in Electronic Data Systems from Electronic Components & Supplies on Aliexpress.com | Alibaba Group (http://www.aliexpress.com/item/Package-Sales-3-pcs-of-Linear-glass-scale-encoder-ruler-DC11-measuring-length-form-50mm/1697204211.html?spm=2114.031010208.3.2.knBJIN&ws_ab_test=searchweb201556_6_79_78_77_80,searchweb201644_5,searchweb201560_6)

.RC.
25th Nov 2015, 09:31 PM
Those scales could very well be very good, I have not heard of that brand name before. I see according to google there is even a local reseller of them around Newcastle somewhere.

Michael G
25th Nov 2015, 09:35 PM
(slightly OT)
Probably about 2 and a bit years ago I bought 2 DROs from the DRO store plus some of the magnetic tape and reader from Machine-DRO in the UK. The magnetic strip reader is RS232 so plugs right into the box, but the best thing about it is the low profile (scale plus protective strip is around 5mm height). I finally installed on the mill around Christmas last year and while it does not get used much it is handy for keeping track of position and especially when trying to locate the centres of holes (in conjunction with the Taster).
(a bit less OT)
One thing I haven't done is installed the DRO on the lathe though. Part of it is sloth - I have another magnetic strip readout that I was going to rebate into the cross slide and that requires all sorts of disassembly, but the other reason is that there is no pressing reason to do so - I only use these things for position and I am struggling to think of a situation where there is a great advantage in having a DRO on a lathe when dealing with one-offs that are usually made to match other parts.
For those thinking of installing scales on a cross slide I would suggest having a look at the magnetic scales if you are pushed for space (Digital Readout Systems | Console | DRO | New (http://www.machine-dro.co.uk/digital-readout-systems-dro-pc-magnetic-glass-linear-scales.html?encoder_series=1138&encoder_type=1101)) (Note that you don't have to use their extrusion to house it either. The mill installation is stuck directly to the table with a cover strip over the top)

Michael

.RC.
28th Nov 2015, 09:35 PM
Bit of an update on this. Some issues to sort through.

Firstly the cheapo android pad I bought like all super cheap pads does not have bluetooth. I originally thought no problems as you can connect via USB. But research shows this is not cheaply/easily possible with the launchpad option.

Secondly, as the reader will be fixed in place I want to run the tablet off a power adapter. Like most tablets the only option for input power is through the USB port. I thought OK, I will remove the battery and pump 3.7V into that. A computer PSU has a 3.5V output, but after removing the case and removing the battery and connecting the PSU and giving it 3.5V the device will not power up at all. Al I get it a quick screen flash showing a battery with an exclamation mark inside it.

However it will power up from the USB port with no battery. So my next option is use the OTG cable that came with the device plug a USB double adapter into that. One side gets the bluetooth reciever, the other gets 5V power source to run the tablet.

BaronJ
28th Nov 2015, 11:21 PM
Hi RC,

A standard computer PSU outputs 3.3 volts and that value is closely controlled. It is just about equivalent to a flat battery. You need 3.7 or even 4 volts ideally. It might be worthwhile regulating the 5 volt rail down to 3.7 with a TO220 variable regulator.

jhovel
28th Nov 2015, 11:51 PM
Richard, you might find as I did that it is not thateasy to find a USB bluetooth adapter that works on Android. ALl the ones I ofund need drivers. You can't do drivers on Android. Most versions of Windows since Win2000 had bluetooth drivers in the Operating systems - that's why you don;t need OEM drivers for them there. But as you may know, when you plug one in the first time, Windows tells you to wait a moment while it finds and installs the drivers for the new device. Android does no such thing....
I gave up and bought one with bluetooth built in.

.RC.
29th Nov 2015, 07:49 AM
I was investigating that Joe and was wondering if that was an older issue that had now been fixed with devices like this that claim android support?

V40 USB 2.0 Bluetooth V4.0 Adapter Wireless Dongle for IOS & Android OS - Black + Silver - Free Shipping - DealExtreme (http://www.dx.com/p/v40-usb-2-0-bluetooth-v4-0-adapter-wireless-dongle-for-ios-android-os-black-silver-250228)

jhovel
29th Nov 2015, 01:20 PM
In theory, Android 4.2.2 onwards has OTG with bluetooth drivers in the kernel. But the internet id full of reports from people that have not been able to get it working. I haven't either.... small chance and worht trying, I guess. Just don't count on it.

.RC.
29th Nov 2015, 06:43 PM
Hi RC,

A standard computer PSU outputs 3.3 volts and that value is closely controlled. It is just about equivalent to a flat battery. You need 3.7 or even 4 volts ideally. It might be worthwhile regulating the 5 volt rail down to 3.7 with a TO220 variable regulator.

I was looking at something like this with a 12V wall wart which I have plenty of 12V TO 3 7V Auminium CAR LED Power Adapter With Short Circuit Protection | eBay (http://www.ebay.com.au/itm/12V-To-3-7V-Auminium-Car-Led-Power-Adapter-With-Short-Circuit-Protection-/191501577371)


In theory, Android 4.2.2 onwards has OTG with bluetooth drivers in the kernel. But the internet id full of reports from people that have not been able to get it working. I haven't either.... small chance and worht trying, I guess. Just don't count on it.

Yes it is a bit of a gamble, I need to root this device and find out what it has installed. At the moment the OS files are hidden from me.

Vernonv
30th Nov 2015, 07:12 AM
I just finished setting up the Pendo Pad and Ardunio based DRO on my lathe over the weekend. While the Pendo pad connects via bluetooth now (with the latest version of TouchDRO), it is still a little dicky and if you disconnect for any reason (like going into the TouchDRO settings) it can be a little difficult to reconnect. I either have to try and reconnect multiple times, or close and reopen TouchDRO, or on one occasion restart the Pendo Pad.

I don't have any of these issues with my Android x86 install and external Bt adapter on an older Windows tablet on my milling machine.

.RC.
30th Nov 2015, 09:23 AM
Android x86. Now I have an old EEEpc here running windows XP. I wonder if that could be used. It is looking increasingly like the pendo pad I have can not easily be made suitable. I doubt there is a cyanogen mod for the pad that would give me bluetooth dongle compatibility.

And the USB option for android DRO does not work with the launchpad controller, which when I saw the USB option available was the reason I got this pad as it was cheep cheep.

Vernonv
30th Nov 2015, 09:27 AM
Android x86. Now I have an old EEEpc here running windows XP. I wonder if that could be used.Possibly. Note that I could not get the internal Bt to work on my tablet (under Android x86), so used an external Bt dongle. But your mileage may vary.

If you are not using the EEEpc for anything else, it's certainly worth a try.

jhovel
30th Nov 2015, 11:54 AM
R.C. the USB option will work with the Launchpad version! You have to get a serial to USB module instead of the bluetooth module though. I can't recall which one to use, but if you email Yuriy he'll tell you the details. The micro USB on board of the Lauchpad is ONLY for power and firmware.

.RC.
30th Nov 2015, 05:11 PM
I have had a look through the android DRO site but cannot find anywhere where any particular module is mentioned. All I can find is where a chap called Joe Hovel asked about it but an answer on what module to use was never got. I have asked the question on the site and will see what answers I get. I do not know if you need special drivers to use those modules or how they work.

There seems to be plenty of different types out there as well eg:

USB to UART 5-Pin CP2102 Module Serial Converter - Free Shipping - DealExtreme (http://www.dx.com/p/usb-to-uart-5-pin-cp2102-module-serial-converter-81872)

CP2102 USB to TTL USB UART Module Serial Converter - Red + Silver + Black - Free Shipping - DealExtreme (http://www.dx.com/p/cp2102-usb-to-ttl-usb-uart-module-serial-converter-red-silver-black-277100)

PL2303 Mini USB UART Board Communication Module - Free Shipping - DealExtreme

http://aud.dx.com/product/funduino-ftdi-basic-program-downloader-usb-to-ttl-et232-module-961397477 (http://www.dx.com/p/pl2303-mini-usb-uart-board-communication-module-149399)

FT232 USB to Serial Breakout Board - Black + Silver - Free Shipping - DealExtreme (http://www.dx.com/p/ft232-usb-to-serial-breakout-board-black-silver-161170)

simonl
30th Nov 2015, 07:15 PM
R.C. the USB option will work with the Launchpad version! You have to get a serial to USB module instead of the bluetooth module though. I can't recall which one to use, but if you email Yuriy he'll tell you the details. The micro USB on board of the Lauchpad is ONLY for power and firmware.

Joe,

I notice Aldi are selling an Android tablet for $100. It has both wifi and bluetooth. Is it luck of the draw as to whether these things work with the Yuri DRO?

Simon

jhovel
30th Nov 2015, 07:45 PM
Richard, he replied to me directly. I looked upo the correspondence. It is this type PL2303 Mini USB UART Board Communication Module - Free Shipping - DealExtreme (http://www.dx.com/p/pl2303-mini-usb-uart-board-communication-module-149399#.VlwL6HYrLIU) that you also listed he recommended.

Simon, the Aldi pad is very likely to work. There is something odd with the chinese very low end pads that is not quite mainstream compatible. ALdi would never allow that to slip through.

simonl
1st Dec 2015, 07:32 AM
Simon, the Aldi pad is very likely to work. There is something odd with the chinese very low end pads that is not quite mainstream compatible. ALdi would never allow that to slip through.

Your logic regarding the Aldi stuff seems sound to me. I would have thought the same thing.

Cheers,

Simon

.RC.
2nd Dec 2015, 10:18 AM
The scales have arrived safe and sound. Just have to work out how to fit them.

.RC.
3rd Dec 2015, 08:27 PM
Now I have worked out the supplied scales have the same pin out as Sino scales, but meister scales use a different pin out profile.

.RC.
7th Dec 2015, 02:30 PM
I think I have ordered most of the stuff I require now.

I went to Jaycar to get some resistors, last time I bought resistors they had 3 stripes to identify size. Now they come with four stripes. So my pre planning of writing down the colour code required before I went into the store was a waste of time.

jack620
7th Dec 2015, 08:15 PM
R.C,
the resistors with 4 bands are 1% tolerance. Shouldn't be a problem as Jaycar sell resistors in marked plastic bags. You don't need to know the colour code in the store.

I always measure the value of a resistor before installing it. It's just too hard to discern the colour bands on the blue resistor. If the resistors are high value, make sure you aren't also measuring your skin resistance.

Good luck with the project.

simonl
9th Dec 2015, 06:46 AM
R.C,
the resistors with 4 bands are 1% tolerance. Shouldn't be a problem as Jaycar sell resistors in marked plastic bags. You don't need to know the colour code in the store.

I always measure the value of a resistor before installing it. It's just too hard to discern the colour bands on the blue resistor. If the resistors are high value, make sure you aren't also measuring your skin resistance.

Good luck with the project.

I agree. I find some of the resistor colours a bit confusing, it's just easier to measure. If you are measuring in the Mega ohm range then don't touch while measuring!

There was a time when both the 3 colour and 4 colour system was used but now it seems it's all 4 colour, or is it 5 including the tolerance?

Simon

RayG
9th Dec 2015, 10:01 AM
Here you go.. :)

359893



Ray

.RC.
9th Dec 2015, 10:16 AM
Flat out seeing the colours these days, bit different to my Dick Smith Funway into Electronics days.

My TTL to USB converter has turned up.

Vernonv
9th Dec 2015, 10:47 AM
Flat out seeing the colours these days ...Yeah, I have to use a magnifying glass ... even then I can have trouble and double check with the multimeter.

I'm amazed how cheap electronics parts like these Ardunios, MSP's and associated hardware are these days (from China). I just received a couple of Arduino Nano's (copies) that cost a little over $3 each delivered. Unbelievable.

.RC.
9th Dec 2015, 05:50 PM
Had a bit of a play today and did a test build. I have found out the writeup on the website is contradictory in what resistors to use (it says to use 200 and 300 ohm resistors, then later on says not advisable to use anything under 2k and 3k resistors)

I plug the USB port into my samsung tablet and when it connects the app crashes. So I plug it onto a windows xp machine and using hyperterminal see what it is doing, it is just sending x0,y0,z0,w0 over and over again, so the problem is in the scale connection. The scales work as I plug them into a reader on the mill and it works it OK.

Just be nice if the instructions were a bit more user friendly.

.RC.
9th Dec 2015, 10:06 PM
I am suspicious now my scales output 3.4V thus do not need the voltage divider. I jumpered over the divider and when connected through hyperterminal moving the scales gives me a reading.

Unfortunately Android DRO still crashes when trying to connect via USB.

.RC.
10th Dec 2015, 05:20 PM
Apparently the PL2303 TTL to USB adapter I bought will not work with Android DRO. However an adapter that should work is an FT232. So I will try one of them.

Lucky all this electronic stuff is cheaper then a morning tea.

I see a plain read out unit at you know who store is $500. I struggle to understand why they are so pricey..

I did not want to add a picture as I did not want to show up Ray with my superior neat electronic workmanship. But anyway.

359919

jhovel
10th Dec 2015, 09:22 PM
Damn, Sorry R.C. I led you astray I think. I was sure I had that advice from Yuryi.... Let us know if you are successful with the FT232 type.

RayG
11th Dec 2015, 08:27 AM
I did not want to add a picture as I did not want to show up Ray with my superior neat electronic workmanship. But anyway.

359919

Looks pretty good to me,,, but remind me later that I must introduce you to the magic of heatshrink and strain relief. :)

The FTDI serial to usb chip is pretty much a standard these days, you can buy it as a cable with 3.3V or 5V compatible connections.
USB TTL Serial (http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm)

Ray

.RC.
12th Dec 2015, 02:53 PM
So who is good with electronics around here.

This is the situation. The MSP430 inputs from the scales have to be less then 3.6V, however the scales get a 5V input and normally seem to output around 5.6V.

The Android DRO website says to make a voltage divider circuit showing a basic schematic and gives some resistor values and leaves it at that.

So I make it like the schematic shows but something odd happens. I do not get the voltage output I should be getting, I only get around 2.2V output which is too low for the MSP430.

However now the voltage output of the scales is 3.4V

picture of diagram of what I have done

359933

Vernonv
12th Dec 2015, 05:20 PM
This seems little unlikely, but maybe you are drawing too much current with your voltage divider, so the scales drop the voltage. Try increasing the resistors to 20k and 30k and see if that makes a difference.

jack620
12th Dec 2015, 06:20 PM
I agree with Vernonv. I think the voltage divider is pulling the output of the scales down. 20K and 30K would be a good start.

RayG
12th Dec 2015, 10:47 PM
Hi RC, Vernon is right, the output driver in the scales can't source the current and so the voltage drops, if you have a couple of red leds, remove the resistive divider and just replace it with a couple of red leds in series with the scale outputs. Red Led's have a forward voltage drop of around 2v. So that will drop the scale output voltage to around 3V. The flat side of the led package should face towards the MSP430.

You might even get lucky enough to have sufficient current to see the scale outputs switching the leds on and off. :)

At the very least, it will get you up and running while waiting for this to arrive https://www.sparkfun.com/products/12009

Ray

.RC.
13th Dec 2015, 09:36 AM
Do you think one of these would work Ray?

IIC I2C Logic Level Converter BI Directional Module 5V TO 3 3V FOR Arduino | eBay (http://www.ebay.com.au/itm/IIC-I2C-Logic-Level-Converter-Bi-Directional-Module-5V-to-3-3V-For-Arduino-/171998721423)

Otherwise I would get one just like you linked to.

RayG
13th Dec 2015, 11:31 AM
Do you think one of these would work Ray?

IIC I2C Logic Level Converter BI Directional Module 5V TO 3 3V FOR Arduino | eBay (http://www.ebay.com.au/itm/IIC-I2C-Logic-Level-Converter-Bi-Directional-Module-5V-to-3-3V-For-Arduino-/171998721423)

Otherwise I would get one just like you linked to.

Ha ha, they ripped off sparkfun's sales blurb as well, then doubled the price... that's a bit cheeky.

The answer is yes, I'm pretty sure they are the exact same device, but, 2 red leds are cheaper, you don't really need bidirectional level shifting. Plus you probably already have them. Just think of the petrol/diesel you will save by not having to drive into town.

Ray

Com_VC
13th Dec 2015, 12:15 PM
4 Channels 4CH Logic Level Converter BI Directional Shifter Module 3 3V 5V | eBay (http://www.ebay.com.au/itm/4-Channels-4CH-Logic-Level-Converter-Bi-Directional-Shifter-Module-3-3V-5V-/121674135202?hash=item1c5457f6a2:g:FUwAAOSwv0tVd91F)

probably a longer wait though

BaronJ
13th Dec 2015, 11:06 PM
So who is good with electronics around here.

This is the situation. The MSP430 inputs from the scales have to be less then 3.6V, however the scales get a 5V input and normally seem to output around 5.6V.

The Android DRO website says to make a voltage divider circuit showing a basic schematic and gives some resistor values and leaves it at that.

So I make it like the schematic shows but something odd happens. I do not get the voltage output I should be getting, I only get around 2.2V output which is too low for the MSP430.

However now the voltage output of the scales is 3.4V

picture of diagram of what I have done

359933


I would suspect that the MPS430 input is very high impedance and the 5k is providing a load for the scales. I would put a 10 k resistor in place of the two that make up the 5k and recheck the scales output voltage. It is likely that you just have to add a load to make both the scales and the MPS430 happy.

I can't remember who made mine but they are fed from two 2032 3 volt batteries and the scales output 3.5 volts across 10K. Also the micro USB connector has the battery voltage across the two end pins and the signals on the center two.

.RC.
18th Dec 2015, 11:06 AM
I have connected in the voltage converter and I am getting 3.6V on the output side. Still waiting on some stuff from China to arrive.

360045

.RC.
4th Jan 2016, 10:49 AM
Things have stalled as china post is a bit slow at the moment. However I did receive a buck boost board. Putting 5V in and turning it to 3.8V out I am able to power the pendo pad from mains power. These boards do make a racket though.

360374

.RC.
9th Jan 2016, 10:51 AM
China post has come through with the goods so far.

Of course as luck would have it. Pendo are now selling seconds of the quad core tablet with bluetooth built in for $50 on ebay. That is the same price they were selling this earlier dual core model I have for.

Anyway, the FT232 USB adapter unit arrived and I have hooked it up and it seems to work sort of. The app seems to have a bug in that it will crash and not save any settings, but then it connects and works.

One interesting feature that has been added is a feed rate in mm/min or in/min. Those of us with milling machines that use those variable speed motors for feed could use this feature to get the feed rates correct for the cutter.

I have some more things to sort out yet. I may go with Ray's idea of a LED to drop the voltage. I found I could not find a ~3V reference voltage on the MSP430 to use to connect to the logic board.

360432 360433

.RC.
23rd Jan 2016, 07:49 PM
I have tried the LED idea to drop the voltage, it does not work.

RayG
24th Jan 2016, 06:02 PM
I have tried the LED idea to drop the voltage, it does not work.

If a red led is too much drop, you can use normal diodes, they will give you about 0.6-0.7 volts per diode, so 5 - (3*0.6) = 3.2V

What voltage did you get with the red led in series?