How to identify beacon data frame using raw data?
what is adv type in beacon data frame?
iBeacon uses a Manufacturer AD Type (0xFF) and Eddystone uses a Service Data AD Type (0x16).
The full iBeacon format is documented in my answer here
Google has documented the Eddystone layout here
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I am working on embedded linux platform and I want to increase data length in BLE communication but I can't find an api function to change data packet length. The module used is SparkLAN AP6256. Is there any configuration parameter to enable DLE (Data Length Extension).
Currently I am using gattool to connect to the device (configured as ble device) and the data length is set to 23 bytes by default. Also tried using btgatt-server and btgatt-client but didn't see any option to enable DLE.
I can encoded an NFC Sticker with a website that will open when I tap it with a mobile phone. For the application I want to use it for I need to be able to expire that link so the user can't just save the URL and use it again. Basically I need to be able to put a random string in the URL that changes each time it gets scanned, such as www.mywebsite.com/TCHQ23, www.mywebsite.com/LQ8FT, ect.
Is this possible with a regular NFC sticker? If not, what kind of device would I use to make this happen? I know there are Arduino modules that can do this, but is there a simpler method or a ready made product that can act as an NFC but have the URL changed by a computer via a USB cable?
Thanks
NFC tags (some) have a feature called "Mirroring". You can mirror the read counter value to the URL, which gets incremented every time you tap it to reader i.e. Every time read command is called, the counter increases by 1. Tags like NTAG 213, NTAG 215 etc have that feature.
Update:
If your requirement is to get a portion of URL to to return random data and on a cheaper tag or sticker then I would suggest considering NTAG 213 tag, which is cost friendly and also have Mirroring feature supported.
If your URL data is http://www.abc#xyz.com then once the counter Mirroring is enabled (read counter must be enabled first) it will look something like
http://www.abc#xyz.com?000001
The last 6 digit value gets increased by value 1,every time a read command is invoked. (000002, 000003, 000004 and so on)
you can refer this link for more info
So your card/device has to present when read a NDEF record with a link in it (A "Well Known Type 1 with a record type definition of type U, etc), this will cause most phones to open a browser automatically
Some details on the Record type needed at https://www.oreilly.com/library/view/beginning-nfc/9781449324094/ch04.html
Most cards have the ability to store some static data, some have as #Adarsh Rotte says have counters, random number generators, crypto, password protection, mirroring (backup) of data, other functions but non of these will help as these custom functions and are card specific and don't / cannot present the data to match the NFC NDEF specification.
There is one type of card that can do this called JavaCard as these can run fully programmable Java Apps. These can be programmed to respond to NFC read request with the right NDEF measure where the URL can be generated on the fly.
There is a github repo with an example Java App to run on these cards that shows how to respond with and NDEF message at https://github.com/OpenJavaCard/openjavacard-ndef.
Watch out for https://github.com/OpenJavaCard/openjavacard-ndef/issues/10 if trying to use this, the default magic AID number is not the right one for NDEF and should be configured at the time you install the App on the Card.
This app emulates the behaviour of an NFC Type 4 spec card.
You would also need to customise it to have the right NDEF payload data with the right generated URL ending.
There are examples of the Card make/model supported by this App listed on the the github pages some are dual interface cards but there are some without the chip contacts and only NFC interface.
Generating the URL ending could be challenging or easy depending on level of security/validation you need.
Starting from a Random String which would be easy to fake because it has no level of validation, to a obfuscated counter, to a public key type encrypted counter.
There are also other solutions to generating the NDEF data with the right URL that don't use a Card and usually require there own power to run.
Some options:-
An Android phone can do what is call Host Card Emulation (HCE) which is very like what the JavaCard is doing, it is pretending to be a NFC Type 4 Card and the response it sends if fully programmable and could be the right type of NDEF message as per the JavaCard.
There are some "Card Reader" Devices that can be attach to a PC/Raspberry Pie via USB can also do HCE like the Android phone. e.g. https://www.acs.com.hk/en/products/342/acr1252u-usb-nfc-reader-iii-nfc-forum-certified-reader/ - this is well documented in the datasheets on how to do.
There are some other "Card Reader" modules that can connect via I2C to Arduino that can do HCE as well. (Technically most Arduino PN532 Chip's which are used in a lot of USB readers as well can do HCE but it is a bit undocumented on how to do it - see section 4 of https://www.nxp.com/docs/en/user-guide/141520.pdf)
There are some other chips that can act as static data NFC devices the also have an I2C interface to write the static data but allow a "pass through" mode to the I2C interface, again these tend to be NFC Type 4 but do some of the HCE type work for you.
e.g. the M24SR04-Y https://www.st.com/resource/en/datasheet/m24sr04-g.pdf can do it
So technically possible with a variety of methods but all not that simple to implement BUT not "Sticker" type format of NFC devices tend to be very simple NFC device as the format restricts the complexity of the hardware contained in them.
I'm eventually trying to use transparent data transmission to pass messages between the mobile SDK and an onboard device using the A3 API/UART port.
Right now I used DJI assistant to output a timestamp to the API port at 1hz. When I connect a TTL>USB device, I see garbage data coming through. When I connect an oscilloscope with a protocol analyzer, I see one frame every second, but the frame is variable size. The ASCII representation of what does come through is nonsense.
I have double checked that baud is set correctly (and have tried other baud rates). I've made sure the grounding is proper. I've tried probing the pin on the actual A3 port (to remove possibility of EMI on the serial cable). It seems like I'm getting garbage data on the serial line, or I don't know how to decode it properly.
Hi，maybe you can refer to the open-protocol of M100 Link.I think it's difficult to decode the protocol of N3,unless DJI publishes that。
I have a Beacon skybeacon Forecum 201 which can advertise as iBeacon or as Eddystone (URL/UID). It has temperature and humidity sensors.
In my project I am using AltBeacon library for monitoring and ranging etc. for working with beacons. As in the examples or docs said, I can get extra data from iBeacon by using getExtraDataFields() method.
When I configure my beacon to transmit as iBeacon, the getExtraDataFields() returns 0, so no sensor values. But when I configure it to transmit as Eddystone UID with TLM than I can read that extra fields, and it returns temperature etc (I tested it with other beacon I have, MINEW E7 beacon and works same way, only as Eddyston UID / TLM sensor values are readable)
I checked even in RadiusNetwork Locate app, and it works the same way as in my app (reads sensor values only when advertise as EddyStone).
So is there any way I can read sensor values on Android with AltBeacon for iBeacon advertisement type? Or it can be only read by Eddystone UID/TLM? So what if working with iOS development and receiving iBeacons?
Mapping of sensors for beacon data fields is dependent on the beacon hardware manufacturer's implementation. In the case of the Forecum 201 it appears that the mapping has been done only for Eddystone-TLM. Other beacon manufacturer's like Radius networks do map beacon sensor fields to AltBeacon. AltBeacon has only a single one byte extra data field that Radius uses to expose the battery sensor. (Other manufacturer's like Kontalt.io do the same.) For iBeacon there are no extra data fields in the layout at all, so it is very unusual for sensors to be exposed by a manufacturer in the an iBeacon advertisement.
Bottom line: you will have to use Eddystone-TLM to read the values from an advertisement with this beacon.
I'm having trouble understanding how OSX formats BLE advertising packet data. In the screenshot below, kCBAdvDataServiceUUIDs in the locals window (on the left) has a certain format that I don't understand (for example, ...376A0). In the log window (on the right), they're printed in a recognizable format (for example, 180D). How is the translation done?
More importantly, I don't understand the kCBAdvSDataServiceData format <3a636401 01>. The service data in my peripheral has 1 byte for the length + 2 bytes for the service + 5 bytes of data. How can I translate the service data into something I understand? In my peripheral, the service data uses 0x180D.
Advertising Data is a list of AD structures.
An AD structure contains:
- length (1 byte) = total length of Type + Data
- AD Type (1 byte)
- AD Data (length-1 bytes)
AD Structures are concatenated to form the Advertising Data.
Same goes for Scan Response Data.
The AD Type is defined by the SIG and has many possible values. As far as I know, iOS/OSX only allows 3 types to be defined by the user: Local Name, Service UUID List, don't know the third one. But there are many more, check the complete list here: https://www.bluetooth.org/en-us/specification/assigned-numbers/generic-access-profile
The AD Data and length is specific to each AD Type.