I was recently diagnosed with Type 1 diabetes. With the need to test my own blood upwards of 8 times a day I have a ton of data to keep track of. My testing unit has the ability to upload its data to a mobile (OTG) or PC (USB).
Sadly, the company who makes the unit does not ship either cable. They are an expensive accessory.
I have enough parts, and should be able to make this, however it's proving difficult.
The USB cable of theirs has windows drivers built into the cable. I was able to get a helpful person at the manufacturer to send me those. That person also told me that OTG wouldn't require drivers.
The photo of both cables on their website show the unit end of the cable as being a 2.5mm (3 ringed) audio jack.
So far I cut open a male USB, I also did the same with the end of an old 3.5mm headphone jack. I then purchased a 3.5mm to 2.5mm adapter. But I'm struggling with the wiring, and trial and error is not producing any results for OTG or USB. I'm also a little concerned that I'll damage my phone, laptop or blood glucose unit. Although all seems to be well after my tinkering.
- My USB has Green (Data), White (Data), Red (5v), Black (Earth) and some sheilding by the looks of it.
- My 3.5mm headphone cable has Red (Normally right audio), Yellow (Normally left audio) and White (Earth)
- I also have a USB to OTG adapter
Note that my adapter has 4 rings, like an ipod shuffle cable or headphones with a mic. I'm assuming that's not introducing any crossed wires as using it for audio still delivers full stereo.
Am I missing something in my approach? If not, how can I figure out which wires connect to which? I would be happy with either a working OTG or USB cable. My tests have shown no response in the mobile app, and only generated USB malfunction errors in Windows (as expected).
Edit: Thanks for all the really good info. I have contacted CareSens for a NFC unit. I will update here when I find out more. This was going to be a fun project during my time off, but it looks like it's a bit more complicated than I first thought.