i have no particular interest in bluetooth, except insofar as i like to know if there are any such devices waiting for me when i walk into a room, and if they are talking about me.
although there are a number of standards relating to bluetooth communications, adherance to the standards by manufacturers is often voluntary. in addition, some of the standards themselves defeat the very purpose of communication.
as a result, interest quickly evaporates, at least for me. this is not unlike "reading" nfc credit cards where - for obvious reasons - one can basically derive more information from a credit card by actually looking at it than by "discovering" it with an nfc tag reader. and the use of proprietary information and encrypted data render reading moot in any case.
so it is, i discovered, with bluetooth. so-called ble devices are supposed to broadcast an "advertisement" touting their features. this is supposed to enable interested parties to learn about the device without going through the trouble of connecting to it (only, presumbably, to learn that one has no interest in the device). the problem is: the space allocated to the advertisement by the controlling parties is limited and, as a result, often conveys little or no useful information about the device. in addition, the advertisement may indicate that the device cannot be connected to (why, then, advertise?) or can be connected to even though this is not the case (and you have to wait 20 seconds before finding this out).
devices which indicate that they accept a connection are a little more forthcoming with their personal data, even though a lot of those data are hidden behind so-called uuid's. many of these uuid's are standardized, and many are customized. devices you connect to will tell you about the "services" they offer, their "characteristics", "descriptors" and associated values. some devices readily share these values with you.
i found scanning for devices to be fun. much like wifi "war driving" of 30 years ago when you could park your car on a strange street and borrow a few hours of precious wifi from somebody's open wifi host. from my little atelier, i can see windows laptop computers, neighbors' apple iphones, printers, giant tv's, speakers, washing machines, "nest" doorbells, "nanny cams", and many other devices whose identities are undisclosed in spite of their claiming to advertise their presence.
it is with the above in mind that i present Advertently, a bluetooth scanner and connector. it reads and decodes (where possible) ble device advertisements. it knows what the various uuid's and their bit-shifted cryptic values mean. it can connect to connectable devices and see what they have to say. and there are actually devices - eg, a heart monitor - whose data can be read without a connection, provided you know which characteristic it uses for such output. advertently can help you find that characteristic. technically, it could write to devices, but i would only provoke my neighbors.
assorted screen shots are attached. although advertisements are relatively short, full connection data can be quite long, longer than our ide log permits. i've saved a sample output to a text file, also attached.
although there are a number of standards relating to bluetooth communications, adherance to the standards by manufacturers is often voluntary. in addition, some of the standards themselves defeat the very purpose of communication.
as a result, interest quickly evaporates, at least for me. this is not unlike "reading" nfc credit cards where - for obvious reasons - one can basically derive more information from a credit card by actually looking at it than by "discovering" it with an nfc tag reader. and the use of proprietary information and encrypted data render reading moot in any case.
so it is, i discovered, with bluetooth. so-called ble devices are supposed to broadcast an "advertisement" touting their features. this is supposed to enable interested parties to learn about the device without going through the trouble of connecting to it (only, presumbably, to learn that one has no interest in the device). the problem is: the space allocated to the advertisement by the controlling parties is limited and, as a result, often conveys little or no useful information about the device. in addition, the advertisement may indicate that the device cannot be connected to (why, then, advertise?) or can be connected to even though this is not the case (and you have to wait 20 seconds before finding this out).
devices which indicate that they accept a connection are a little more forthcoming with their personal data, even though a lot of those data are hidden behind so-called uuid's. many of these uuid's are standardized, and many are customized. devices you connect to will tell you about the "services" they offer, their "characteristics", "descriptors" and associated values. some devices readily share these values with you.
i found scanning for devices to be fun. much like wifi "war driving" of 30 years ago when you could park your car on a strange street and borrow a few hours of precious wifi from somebody's open wifi host. from my little atelier, i can see windows laptop computers, neighbors' apple iphones, printers, giant tv's, speakers, washing machines, "nest" doorbells, "nanny cams", and many other devices whose identities are undisclosed in spite of their claiming to advertise their presence.
it is with the above in mind that i present Advertently, a bluetooth scanner and connector. it reads and decodes (where possible) ble device advertisements. it knows what the various uuid's and their bit-shifted cryptic values mean. it can connect to connectable devices and see what they have to say. and there are actually devices - eg, a heart monitor - whose data can be read without a connection, provided you know which characteristic it uses for such output. advertently can help you find that characteristic. technically, it could write to devices, but i would only provoke my neighbors.
assorted screen shots are attached. although advertisements are relatively short, full connection data can be quite long, longer than our ide log permits. i've saved a sample output to a text file, also attached.
Attachments
Last edited:
