Connecting iGaging Scales to TouchDRO Controller

Sunday, December 4, 2016

If you read some of the earlier posts on this blog you will quickly see that the times were much simpler four years ago when it comes to iGaging scales: there was only one kind and red wire was "Vcc", black wire was "Ground", and so on. Since then iGaging has gone through several revisions of the original DIgiMag scales and has introduced AbsoluteDRO and EZ View scales. My goal for this post is to explain what are the different iGaging (and generic scales made by Shahe) that TouchDRO supports and how to connect them to the BlueTooth DRO controller.

I will use TouchDRO iGaging BlueTooth controller as the example but this applies to the Mixed scale kit or a scratch-built controller. For scratch-built controller please refer to the post that details MSP430 LauchPad pin functions for TouchDRO. Details about TouchDRO Mixed Scale Controller kit can be found here

Introduction

Since they were first introduce several year ago, iGaging "Remote DRO" scales have gone over several revisions. I've encountered at least six different PCB version for the DigiMag scales (and their generic counterparts) and three revisions of the AbsoluteDRO scales. For the purposes of connective them to the TouchDRO board you need to keep the following in mind:

  • All variants of the "classic" iGaging scales use the same 21-bit protocol, but the timing and the output circuitry varies a bit.
  • The oldest version of AbsoluteDRO scales are not supported by the TouchDRO board; two newer version differ only in the USB connector and pin assignment they use.
  • iGaging changes the cables from batch to batch, so using color of the wires as a guide to the pin functions is not practical (and can damage your scales if you mis-wire them).
  • Earlier versions of DigiMag scales were a bit more noise-prone but had more robust output stage. Newer ones are more stable but can get permanently damaged if the output stake is overloaded. In other words messing up wiring on the older scales was pretty much harmless to the scales; grounding or connecting the data pin of the newer scales to a low-impedance "sink" can let the magic smoke out.

Side note: If you shop around you are likely to find scales that look identical to those sold by iGaging but have no branding. I've seen a few sellers of iGaging scales calling the non-branded scales "cheap knock-offs". In reality these are the same scales. Both are manufactured by the same company called Shahe and besides the missing iGaging logo, there is no difference.

You have two options when it comes to connecting the scales to the TouchDRO controller: you can cut and strip the cables and connect them directly to the board, or use the appropriate USB breakout boards and connect the scales that way. Cutting the cable is cheaper, and might be preferable if you don't feel comfortable soldering, since TouchDRO iGaging board uses screw terminals for scale connections. On the other hand breakout boards will give you more flexibility in future.

Cutting the Cables

If you decide to take the "no soldering" approach and wire them directly to the board, you will need to determine wire function by checking continuity between a set of test points in the reading head and the exposed ends of the wires. To be safe, it's important to do this for each of the scales. Don't assume that just because you got the scales from the same supplier wire colors will be the same.

You will need the following tools:

  • Wire stipper (please don't use your teeth. Dental work can be very expensive)
  • #0 Phillips screwdriver
  • Multimeter that can measure resistance or continuity

Start with carefully removing the four screws and removing the top plastic cover. As shown in the pictures below, next to the USB connector you will find a set of round test points. Depending on the revision, your PCB might look slightly different but it will be similar enough to one of the examples below.

AbsoluteDRO+ Scales

There are four test points: Data, Clk, Vdd and Req; ground can be checked against the square pad, as shown in the picture.

iGaging AbsoluteDRO+ Scale Reading Head Test Points 

The connections should be as follows:

Test Point TouchDRO Line
VDD 3.3V
DATA Data
CLOCK Clock
REQ Ground
Frame Ground

Non-Absolute Scales

This includes DigiMag, AccuRemote, EZ View and unbranded Shahe scales. All of these scales use 21-bit protocol and will have three round test points: VDD, SSY, and DATA. Ground can be checked against one of the square pads or the scale frame.

iGaging Scale Reading Head (Mini-B version) Test Points

The connections should be as follows:

Test Point TouchDRO Line
VDD 3.3V
DATA Data
SSY Clock
Frame Ground

Using USB Breakout Boards

Start by identifying the type of the connector your scales use. All of the iGaging/Shahe scales supported by the TouchDRO iGaging BlueTooth adapter board will fall into one of three categories described below.

Mini-B USB (left) and Micro-B USB (right) Connectors

AbsoluteDRO+ with Mini-B USB

These scales require a Mini-B USB breakout boards and use somewhat unconventional connection scheme. The connection are as follows:

USB Pin TouchDRO Line
5V Ground
D- Data
D+ Clock
ID 3.3V
GND Ground

It was quite difficult to take a good picture with the five wires, therefore the picture below shows only the Vcc, Groun and Req connections for clarity. Data and Clock connect straight across and should not cross each other.

iGaging AbsoluteDRO+ Scale Connections

It was difficult to get a good picture with all wires connected. The picture blow shows Vcc, Ground and Req. connections. Data and clock wires connect straight across (i.e. they should not cross)

Non-Absolute Scales with Mini-B USB Connector

This includes the classic iGaging DigiMag Remote DRO scales and the AccuRemote scales, as well as the non-branded Shahe scales. The connections are as follows:

USB Pin TouchDRO Line
5V 3.3V
D- Clock
D+ Data
ID Not Connected
GND Ground

Once done, the connection should look similar to the picture below. Please note that Data and Clock tables are crossed over.

Connection for iGaging Scales with Mini-B Connectors

DRO Scales with Micro-B USB Connector

Update May 20, 2017: There is now a "Ready to Go" version of the controller that has Micro-B connectors pre-installed, so this section is no longer relevant

This includes AbsoluteDRO+, DigiMag/AccuRemote/Shahe "Remote DRO", and EZ View scales that use Micro-B USB connector. It appears that iGaging/Shahe finally came to their senses and decided to use the same connection scheme for all of their scales. The connections are as follows:

USB Pin TouchDRO Line
5V 3.3V
D- Clock
D+ Data
ID Ground
GND Ground

The finished product will look similar to the picture below.

Connection for iGaging Scales with Micro-B Connector

Conclusion

As you can see, connecting your scales to the TouchDRO Bluetooth Controller for iGaging scales is pretty straight forward and can be done without soldering. For those not comfortable with soldering TouchDRO iGaging adapter offers the option of mechanical connection via the screq terminals. Unfortunately the manufacturer changes the cables often, so a bit of detective work with a multimeter is required. On the other hand, using the breakout boards requires some soldering but the connections are more straighforward, since the USB pin functios are clearly maked on the PCB.

13 comments :

  1. thanks for the write up. This makes things a lot easier. I do have a question. I have one scale that is a micro-b but i only have mini-b connectors. If i use a converter to go from micro-b to mini-b will the wiring be just like it was a mini-b connection?

    ReplyDelete
    Replies
    1. Yes. The adapter should still map pins to the same functions.

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  2. Hi...I have 3 Igaging dro plus units. Two are mini-b and one is micro-b .My question is can I interchange reader heads from one size scale to another size scale and what percautions if any do I need to take. Display heads and readers stay together as pairs.
    Thanks....Casey

    ReplyDelete
    Replies
    1. Casey,
      I haven't tried that, so I can't say for sure. Since both types have same resolution, it's reasonable to expect that the encoder strip is the same. Try it and see what happens. Unless you mechanically break something, you can't damage the electronics that way. Just make sure you don't install the heads 180 degrees off or damage the brass gib.

      Regards
      Yuriy

      Delete
    2. Hi Yuriy....Thanks for your reply. I'll try it so I can keep all Mini B cables on one machine
      Thanks....Casey

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  3. Hi Yuriy.....On my Igaging Absolute DRO Plus display head there are 3 female jack ports....one for the reading unit mini B and one for power and the third is oblong shaped (looks like Type A USB) My question is what is the third jack port for......it is located right beside the mini B port.
    Thanks......Casey

    ReplyDelete

  4. I have the TouchDRO BlueTooth Adapter Board for iGaging Scales, and have used the instructions on the site for same to the best I can. I am using the "Chinese knock off" scales. they have worked on their own on my HF mill. I cannot get them calibrated. I've tried multiple times, and the closest I got the "X" axis was 3.199. It doesn't seem tobe able to stay zeroed out.. Also I can't get the tach. I was using before to work. What I thought was the way it should be wired, doesn't seem to work on the Touch DRO. I am using a 7" Fire (5th generation tablet, I think it was one that was recommended. I know this is long and I probably didn't add pertinent info. But can I get some help to find a starting place. I'm waiting for comments, questions . . . what ever. Thanks, Pierre

    ReplyDelete
  5. re: It doesn't seem to be able to stay zeroed out
    I ruined one of my DROs because I put a twist on the sensor which caused constant tension causing the the readout to constantly jump/move. Make sure your linkage is relaxed and not put a twist on.

    re: Also I can't get the tach, What I thought was the way it should be wired, doesn't seem to work.

    Do you have a multimeter or at least a indicator LED? I do not know what you have for a sensor but "most" have three wires Vcc (+), Out, and Gnd (-). Out should be a pulse if Vcc is 3 volt then you should see a 3 volt pulse, connect the Out wire to your Tach terminal.

    I have the iGaging adapter board and it works great.

    Ralph

    ReplyDelete
    Replies
    1. Thanks for the quick response. I'll double check everything, plus what you suggested. Pierre

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  6. I'd like to get the iGaging scale set that uses 3 stainless steel scales, rather than aluminum. Can someone tell me if those are compatible here, and what source in the US would be the best place to get them? If they are compatible, can I simply follow the directions here, using the USB breakout method?

    ReplyDelete
    Replies
    1. There are two models that use stainless steel frames: AccuRemote (not iGaiging, but the same basic scales) and iGaging Absolute DRO+. If you get them with Micro-B USB connectors, you don't need breakout board. The "Ready to Go" board is pretty much ready to go, with the connectors preinstalled. If you get Mini-B, breakout boards is the better way to go.
      Regards
      Yuriy


      Delete
  7. I have the TouchDRO BlueTooth Adapter Board for iGaging Scales, and have used the instructions on the site for same to the best I can. I am using the "Chinese knock off" scales. they have worked on their own on my HF mill. I cannot get them calibrated. I've tried multiple times, and the closest I got the "X" axis was 3.199. It doesn't seem to be able to stay zeroed out.. I've tested it multiple times on a 1 2 3 block and it has never said it was 3". I'm really disappointed, and have pretty much given up on it. I use it because I cut the the wires on the original gauges. But I don't trust it to give me any kind of accuracy. I am using a 7" Fire (5th generation tablet, I think it was one that was recommended. I know this is long and I probably didn't add pertinent info. But can I get some help to find a starting place. I'm waiting for comments, questions . . . what ever. Thanks, Pierre

    ReplyDelete
    Replies
    1. Pierre,
      First off, can you please post this in the forum. It's easier to communicate there and more people can chime-in.
      That said, do you see this happening to all four inputs or just the X axis? What happens when you enter 2560 as the CPI for the axis. Do you get close to 3.000?
      Regards
      Yuriy

      Delete