Advice needed: micro board with host USB and bluetooth LE

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Hi,

I’m new to the forum and would be grateful for some advice. I would like to build something to connect to a Glucose meter via USB, and upload the results to an iPhone via bluetooth. I would like the device to be as small as possible and of course have a battery that lasts a year.

The glucose meter is downloadable to a PC via UsB so if The micro board has a host USB port then I should be able to get the data off the glucose meter.

There looks to be a health device protocol for bluetooth and CSR has a reference design and sample iPhone code, so it looks like I can then get the data to the iPhone.

It’s not something I’m looking to commercialise and so whatever I prototype would probably be the finished item, which should be as small as possible.

The two options I am considering are:

  1. A small micro with two host USB ports, with a bluetooth dongle in one of them, and the glucose meter into the other.

  2. Using the Intel Edison as this has bluetooth and a USB OTG port built in. I’m not very familiar with USB but it seems that non-OTG devices are backwards-compatible with OTG. I take this to mean if I put a non-OTG device into an OTG host, it will work.

Has anyone done this sort of thing before, or have any comments on which option might be more fruitful? It’s a long time since I did anything like this and there’s lots to learn!

Any advice would be gratefully received. Thanks!

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I’m confused a little. If the glucose device has a USB port and you’re willing to plug a device into it and then plug that device into a PC … why do you need Bluetooth ? Just to communicate PC to Iphone ? Aren’t there many other ways to do that ? Why not connect the glucose meter to the IPhone directly, via some form of BT ?

Or is that what you’re looking for ? If so can you give us some link to the “glucose meter/device” ? There are SoC’s w/BLE built-in (Edison is one, Nordic’s nRF51822 is another) but how they may interface to the glucose meter is a question. Then again there are Arduino’s that could act as a USB host (I think) and also talk to a [BLE link. Before you go down that route, it makes sense to take a careful, deep look at your intended system.](Bluefruit LE - Bluetooth Low Energy (BLE 4.0) - nRF8001 Breakout [v1.0] : ID 1697 : Adafruit Industries, Unique & fun DIY electronics and kits)

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Hi,

Thanks for your reply. The glucose meter is a http://www.dexcom.com/dexcom-g4-platinum Dexcom G4 - this is a continuous glucose sensor which sends glucose readings every five seconds. The transmitter sits on the skin and sends the readings to a handheld receiver which displays the readings on a graph. This is great, but it only displays the last 24hours worth of readings. It is very handy to be able to go back a couple of days and see what glucose readings were a few days ago.

This could be achieved by downloading everything to a PC each night, but i’m looking for a mote automated solution.

There is a very cool project called http://www.nightscout.info/ NightScout which achieves this by hooking up the receiver to an Android mobile phone (which then sends the results to the cloud) but I thought it would be interesting to look at a SoC to do the same thing via Bluetooth LE to an iPhone, or any other phone for that matter. I would like to use Bluetooth as I don’t want it plugged in to my main phone all the time.

The Nordic chip looks interesting but lacks the host USB - IMHO it would be a bit of work to add one plus a USB stack. I think the combination of host USB and Bluetooth will be quite uncommon, which is why the Edison looks so interesting, assuming the USB in OTG mode can act as a host to the Dexcom receiver.

What do you think - do you think the Edison could work, or are there any other SoCs out there which might be suitable?

Thanks

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I would go a step further and upload to the “cloud” directly from the CGM device. Perhaps using a BeagleBone since I have one on hand. If you don’t mind making your data public, SparkFun’s Phant project would be great for this.

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lyndon:
I would go a step further and upload to the “cloud” directly from the CGM device.

You have to wonder why the Nightscout people didn't do that. My guess is that the RF stream from the sensor/x-mitter is encrypted.
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If you go the beaglebone route you still have to connect to a cellular network so need something that will connect to a 3 or 4G network. The nightscout solution is good because you leverage an easily programmable, cheap computer with a cellular connection.

I’m not sure what you mean by uploading the data directly from the CGM device? Also, not too keen on having the data publically available as it is personal health data.

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BTW does anyone know when the Edison is due to ship?

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sachams:
I’m not sure what you mean by uploading the data directly from the CGM device? Also, not too keen on having the data publically available as it is personal health data.

I took it to mean that instead of receiving and storing the data in the G4 receiver/display unit, you'd use the smartphone instead. I believe the sensor/transmitter on the patient transmits it's data via some Bluetooth format to the receiver/display unit. Given it's a measurement every 5 mins, it's well suited to a BLE/Bluetooth Smart application. The question is (if I'm correct in prior assumption) do you want to commit a smartphone to be in proximity to do the recording/storage task ? If not then you're back to your idea or the NightScout idea. Or some sort of very tiny (phone<-adapter/USBhost->receiver/display unit) [[WiFi solution](http://hackaday.com/2014/08/26/new-chip-alert-the-esp8266-wifi-module-its-5/)??

FWIW I don’t think you want your “adapter” to be BLE/BT Smart. That protocol is intended for a sporadic low data count usage. You seem to want to dump the data stored in the receiver/display unit to the adapter to the … smartphone/Cloud/whatever. Unless this is being done as the data is received** by the receiver/display unit, it implies a higher data rate than BLE. More like the SPP protocol under BT 3.0.

** and then you’re back to some real-time link to the Cloud via 3G or WiFi.

JASI - have you considered some dongle for the iPhone ? Or do you want remote access via the Cloud or some other network ? If no to the latter, you might get an IRda dongle for the phone and then your adapter only has to have a USB host capability (to suck the data from the receiver/display unit) and an IR transmit capability.](New Chip Alert: The ESP8266 WiFi Module (It’s $5) | Hackaday)

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Instead of “directly from the CGM device” I should have said “directly from the interface.” i.e., circumvent the iPhone, but I didn’t realize the reason you are using a phone is for the cellular connection.

As far as why they didn’t do it themselves, just wait a bit. I’m sure it’s coming. I’ve been involved in remote monitoring for a while (hate that Internet of Things term) and it is spreading rapidly. Started out being used for monitoring expensive machinery, but as the costs of WiFi/cellular interfaces drops, you’ll start to see more and more devices uploading data. I predict that online data hosting/presentation tools will sweep the industry the same way web hosting services did.

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Hi both - thanks for your thoughts. Some comments:

I believe the sensor/transmitter on the patient transmits it’s data via some Bluetooth format to the receiver/display unit

Not sure it’s BT but probably a proprietary format. It would be ideal to intercept this data but I don’t think this is a option without cooperation from Dexcom, which IMHO would be difficult to obtain.

The question is…do you want to commit a smartphone to be in proximity to do the recording/storage task?

Yes, though not ideal, I think this is acceptable. I always have my phone with me. Bear in mind that the receiver will be logging the data so when the phone is not in proximity the data isn’t lost, it will be buffered by the receiver.

FWIW I don’t think you want your “adapter” to be BLE/BT Smart. That protocol is intended for a sporadic low data count usage…Unless this is being done as the data is received

The majority of the time it will be done as it is received. There may be periods (eg a couple of hours) where data was not received by the phone and the phone has to sync any unsynced data. 2 hours worth of data at, say, 8 bytes per reading every 5 mins is <200 bytes.

Or some sort of very tiny (phone<-adapter/USBhost->receiver/display unit) WiFi solution??

That module looks pretty neat but it lacks USB host which would need to connect to the Dexcom receiver. It ticks lots of other boxes though, in terms of size and probably power usage. One reason I thought of BLE was power consumption - I figured a BLE connection between the adapter and the iPhone would draw less power (both on the phone and the adapter) than wi-FI. I’m not sure what the power draw of the Edison is, but I would imagine that it is quite chunky, which is not ideal.

have you considered some dongle for the iPhone…you might get an IRda dongle for the phone and then your adapter only has to have a USB host capability (to suck the data from the receiver/display unit) and an IR transmit capability.

Yep, I was thinking of that, but using a BLE dongle on the adapter, so that the adapter would only need two USB host ports and not BLE. This might lead to more options. Do you know of any? IR wouldn’t be right as this requires line of sight, and the receiver could be in the bottom of my bag.

As far as why they didn’t do it themselves, just wait a bit

For sure it’s coming, but like all things diabetes-related, it takes a long time, hence the movement #wearenotwaiting. - see https://mobile.twitter.com/search?q=%23 … ing&s=tyah for more info. FDA approval is not quick and if I’m only building something for myself I’m less bothered if it is FDA approved! :slight_smile:

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It would seem that Edison is a fair all-in-one solution. I say fair as I think your power concerns are well founded and any SoC running some version of Linux isn’t going to power down and sleep as easily as a MCU based system. One last thought to toss your way is to build up a system that can sleep though it wouldn’t be a small as an Edison.

For a USB host …

http://www.circuitsathome.com/products- … -pro-mini/

Controlled by a Pro Mini …

https://www.sparkfun.com/products/11114

Talking to your iPhone via BT Smart using this …

http://www.adafruit.com/products/1697

No doubt there are MCUs that have USB host functionality, I’m just not that familiar with them.

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Great, thanks for the links and your comments. I’m still hopeful there is an MCU out there with BLE and USB OTG/USB Host but so far I haven’t found it! The other option is to bite the bullet and to either get a MCU with BLE and add a USB host or vice versa.

Google, you and I are going to become very good friends… :slight_smile:

cheers

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One other idea … you might find some virtual USB host code. Just as there’s [V-USB that allows Atmel MCUs (even ATtinys) to be a USB device, there might be the equivalent for USB hosting. I dunno. For SoC systems running Linux, like an Edison or RPi or ???, there’s this.

http://sourceforge.net/projects/usb-vhci/](Learning To Use The V-USB (AVR USB Firmware) Library | Hackaday)

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Cool - thanks again! Will check out the links.