BLE Sensor Tag Demo Module for Android/iOS - Review

Table of contents

RoadTest: BLE Sensor Tag Demo Module for Android/iOS

Author: baldengineer

Creation date:

Evaluation Type: Semiconductors

Did you receive all parts the manufacturer stated would be included in the package?: True

What other parts do you consider comparable to this product?: Numerous BLE Tag boards from other vendors.

What were the biggest problems encountered?: There is no way to measure current. The board offers no mounting options for use in a prototype. The mobile app is very limited in functionality.

Detailed Review:

 

 

Important Notes

This RoadTest is unique for me because I am RoadTesting the wrong device. Here is what happened. My normal process for these reviews is to avoid reading other reviews while writing mine. I do not want the experience of others to bias what I say or test. However, afterward, I like to compare them to see if I missed something. My intention is that I'm less likely to remove my bias. In this case, I realized, my board didn't match the other two reviews. Why?

 

Well, element14 sent me a module in December. I threw it in my bag with the intention to do some testing over the holiday break. However. I couldn't find it after that. Assuming I had lost it, I decided to "do the right thing" and buy my own module to replace it. After all, it was only $20, and I needed to order other stuff from newark.com anyway. That was in early January.  As with most lost items, a few days after getting the new one, I found the old one. Until writing this review, I did not realize the board is different.

 

Road testers were sent a WPP100B001 while the "Buy Now" link leads to the WPP100B009, which is what I bought. To be frank, the TE datasheets make identifying these boards nearly impossible. With that said. The comments about the module, the mobile app, and the sensor performance are all the same between the two boards. The only difference I feel I should mention is that the WPP100B001 actually comes with two temperature sensors on board.

 

The WPP100B009 Module

The unit arrived in an unremarkable box. It took me a few minutes to figure out what exactly it was. Then I remembered I was selected for the RoadTest. The antistatic bag provided limited clues to a starting point. Eventually, I found the datasheet, which has a section that tells you which guide to download based on Android, Windows, or iOS. I've provided links here to save you the google search that the datasheet forces on you.

 

The board measures about 20 mm by 43 mm. In the picture above, you can see the business side with the micro, radio, and sensor. The backside is just a clip for the 2032 battery. As an evaluation module, I think this board misses the mark, significantly. The sensor package is touted as a low-energy solution. However, this board provides zero means for measuring current consumption. I suppose you could de-solder the battery clip and put some wires there. But it would have been nice to have some pads or something to connect with. Keep in mind that when measuring the kind of current this device would draw, you need a very low burden ammeter.

 

Next, there are no easy access points to talk to the sensors. Which means if I wanted to implement my own BLE radio chipset, this board would not be of much use. I can't talk directly to the sensors, only through the onboard BLE. I can't even use this as a reference design because the data sheet for the module does not say what chip is being used.

 

My final issue with the module is that there is no way to mount it into any kind of prototype. There are no mounting holes. And because of how the battery clip is attached, there are no clean edges for a clip. So the board really only exists as a platform to test the silicon but not test it in an application. I'm not all that happy with the board, so let's see how the sensors perform next.

 

The Mobile App

In my setup, I only have an iOS device to test with. I don't have a Windows computer nor do I have any Android devices (available). The instructions say to search the App Store for "TE Connectivity Sensor Solutions" or "MEAS Sensors Tag." At the time of writing, neither is in the store. There is, however, a "TE Sensor Tag" app with the same icon, so I installed that one.

 

 

After launching the App, I had to press the small button on the board to start BLE operation. There is a blue LED that flickers quickly. The device immediately showed up in the list and I tapped it.

 

 

Out of the gate, the app is showing me the temperature, humidity, and barometric pressure data. Those are the three things that the MS8607 measure. The graph seems a bit erratic to me, but it is due to the graph's scaling. So do not let the jagged readings throw you off. Sitting on my desk, all three measurements are relatively stable. (Note with the silicon on the WPP100B001 you would only see humidity and temperature on this screen. Barometric pressure was available by selecting another sensor.)

 

 

It was at this point, I realized the app could not be rotated. To me, graph data lends itself best to landscape mode but this demo app is stuck in portrait. Here an example of why that is annoying. Here are two screenshots, side-by-side, where I grasped the TE sensor tag into my hand. You can see it reacts to the increased heat from my body, but it takes me two screens to see the trend. Also, am I missing the time scale on the X-Axis?

 

 

For what it is worth, my Braun ThermoScan infrared thermometer says my body temp is currently 36.9°C. Granted, that is measured in my ear. Sorry element14 community, but I am not sticking the TE sensor tag into my ear.

 

Now my complaints with the app might be brushed off. After all, the datasheet gives you some bare minimum information on how to communicate with it using BLE. However. In my opinion, the spirit of this test is the module itself. So to me, that includes the software that comes along with it to demonstrate the hardware. But more on my feelings about that in a bit. For now, let's go to another extreme and one that has a bit of calibration associated with it — my freezer. I placed the TE sensor tag into the fridge and shut the door.

 

Recording Freezing Temperatures

 

 

By the way, you might notice two things: my freezer is mostly empty and I have a box of thin mints. The attached note is from my brother. He sent me the secret recipe for making the famous Thin Mint cookies yourself.  Please do not steal this, now, family recipe.

 

While it was in the freezer, I used the App's record mode to see what it would capture. It creates a CSV file with Date, Humidity, Temperature, Pressure, and the battery's level. You hit the record button, let the app run for a while, and then tap it again to stop it. On iOS the share sheet automatically opens. I saved the file to my iCloud Drive so I could open it on my computer. On my first attempt, I did run into one issue. I wanted to show the temperature change from idle to running. I collected data for about 15 minutes. When I stopped the recording, the app crashed. So I lost that track.

 

 

Even though the file saves as a "comma separated values," the separator is a semicolon. I threw the data collected into a google sheet and graphed it. The TE iOS app saved samples at one-second intervals.

 

The freezer control panel says it is set to -17 °C. The graph above is sitting in the freezer while it ran for about 10 minutes. The yellow battery level is useful because it tells how cold the board itself is getting. As it gets colder, the battery’s ESR goes up and its output voltage goes down. Looks like the compressor is blowing out a consistently cold temperature. Can anyone help me understand why the relative-humidity would shift so much? Is it related to how a freezer works? (See below.) Now that the board has soaked for a while, let’s see how it reacts to an idle freezer.

The red line slightly trends up and to the right, as you expect. The freezer is slowly warming up over about a 6-minute span. Relative-humidity is also tracking the temperature change, which I would expect to see. And that poor battery. It is just getting killed by the cold temperatures!

 

 

I did grab my thermal attachment to see if it agreed with the temperature readings. For some reason, it was taking the picture upside down. So I've provided a right-side-up PIP-view of the temp reading. It says -12°C which I say agrees with the readings from the sensor board. (It took almost a minute for me to get the camera picture to work so I expected the temps to be slightly different.)

 

Conclusion

Regarding the sensors, they operate as expected. My disappointment is with the overall module. As an evaluation board, there isn't much I can evaluate other than some of the stuff I provided above. The lack of any easy way to measure current is really a bummer. I would have liked to experiment with ultra low current measurements, but I didn't want to go to the extreme of modifying the board. My inability to mount the board to anything totally leaves out an opportunity for me to put it into a project or prototype.

 

So the overall value is "reasonable." The board is less than $20 on newark.com. You'll get a good idea of how the sensors work, though you'll be limited to how you can test them.

Anonymous
  • Yes, despite what I alluded to, I would agree with you that it does seem rather odd that there is no way to mount it to a fixture.

     

    On this issue of software development, I would argue that if the intention of the tag is merely to provide you with the data via BLE bridge then they have provided everything that you need, namely service UUID and characteristic UUID's together with the data structure. Your own custom application would then be developed on another device, such as smartphone (as they have done with the demo app) or via another BLE device, which would connect and read this data stream. The basis of Bluetooth LE is that it is intended to be device agnostic and so it is not necessary to know what chipset is being used. Nevertheless, based on your picture, it looks like they are using a Texas Instruments CC2541 BLE chipset.

     

    Aha, I did not think about the possibility of region-specific separators being used for decimal place. Thanks for pointing that out.

  • Hence, mounting holes aren't required as it is merely intended that you drop the tag in the field environment and you measure the stats etc. for the defined test period etc

    I do not agree. To "drop it into an environment" you are likely to mount or attach it to something. With no holes and no clear space to use a clip, your only option is to use double-sided tape, glue, or hold it in your hand.  The glue and double-sided tape options aren't that great because the battery bulges the back side and the top side has the sensors. Holding it in your hand will definitely alter the results.

     

    The only way to "test it in the field" is to mount to it a fixture.

     

    After a while, I thought maybe the module is intended to help with software development. But then I remembered that you can't access the sensors I2C data pins and there is no information on what BLE chipset is being used.

     

     

    As to why the saved csv file uses a semicolon instead of the default comma as a separator is anyone's guess.

     

    I suspect whoever wrote the App didn't want to deal with the region-specific separator.

  • A great review. I believe the best insight is gained when things go wrong. Hence temporarily losing the device and ordering the other one helped illuminate the subtle differences in model numbers. It is nice to know these things.

     

    I too have pondered about the value of these demo type sensor tags and why more companies are producing them. So I found your documented expectations and experiences rather helpful in this regard. It was the following comment that got me thinking

     

      wrote:

     

    My final issue with the module is that there is no way to mount it into any kind of prototype. There are no mounting holes. And because of how the battery clip is attached, there are no clean edges for a clip. So the board really only exists as a platform to test the silicon but not test it in an application.

     

    So, yes you are right in that it is a platform to test the silicon but, in my opinion, it might also be in such a form factor to help you evaluate that silicon (or use that silicon, if you trust it) in a field testing scenario to help you measure and understand the dynamic changes in the operating environment for your application. Hence, mounting holes aren't required as it is merely intended that you drop the tag in the field environment and you measure the stats etc. for the defined test period etc. and remove when finished. As to why the saved csv file uses a semicolon instead of the default comma as a separator is anyone's guess.

  • Maybe there was moisture condensing because you had recently put the sensor in the freezer?

     

    Ahhhh yes. That is probably the case. The reverse happened when I removed it from the freezer. A very thin layer of condensation formed and the reading shot right to 100%.

  • Good review James. The board looks useful and fairly cheap,  I always like reading about the limitations.  I often find ‘apps’ functionality very limited. The rel. humidity graph with freeezer running is strange, if the cold dry air is blowing, the % should be going down,not to up. ? Maybe there was moisture condensing because you had recently put the sensor in the freezer?

     

    i always like a little humor in reviews.  Good thin mint recipe. Those things are addictive. I know you said not to steal the recipe, so I won’t.  Usually my recipe is, I open my wallet and pay the girl’s parents. :-)

  • Nice roadtest review.  I can understand a lot of the frustrations that you mentioned in your review.  An evaluation module should allow you to evaluate the part (and tell you what part you are evaluating) and provide an easy way to examine all of the parameters of interest (like current).

     

    Wow that is a clean and very empty freezer.

     

    Gene