How many devices can we connect via Bluetooth from BLE to Android?

Question

How many devices can be connected simultaneously via Bluetooth using BLE firmware on Android?

Answer 1

A search for the Bluetooth firmware source for Android shows the following:

Maximum number of simultaneous active synchronous connections ( BTA_GATTC_CONN_MAX ):

• 4 on Android 4.3
• 7 on Android 4. 4+

Maximum number of simultaneous active notifications ( BTA_GATTC_NOTIF_REG_MAX ):

• 4 on Android 4.3
• 7 on Android 4.4
• 15 on Android 5. 0+

For comparison, my experience with iOS is that you can connect 8 devices at the same time.

The other day, I tried to connect more than 7 devices on Android 7.1, and Bluetooth stopped responding. Starting and stopping did not help; the only thing that fixed it was restarting the device.

After working with several applications that connect to 4+ devices, I can say from experience that these numbers are theoretical. Depending on each individual device and its hardware, it will be easier or harder to connect and maintain a connection with as many BLE devices as possible.

Answer 2

Follow Bluetooth on Wikipedia,

The main Bluetooth device can communicate with a maximum of seven devices in a piconet (a special computer network using Bluetooth technology), although not all devices reach this maximum.

First you need to know Master/Slave in Bluetooth.

I think a good answer depends on your goal.

You are right when you know "can communicate with how many devices" depend on Hardware (Bluetooth Chip) . Bluetooth chip on Apple iPhone 4, 5 or Samsung Galaxy S3, S4 ... totally different with Basic Bluetooth Chip .

In my case:

I work with the firmware side related to BLE.

His peripheral device has used Basic Bluetooth Chip , because he did not have enough memory to store many features, like many functions, he likes the Bluetooth chip on Apple iPhone 4, 5 or Samsung Galaxy S3, S4 ....

Therefore, his peripheral device only paired with one device in one time .

Thanks,

Answer 3

Both answers are desired here, so I thought I should add one:

There are connection restrictions built into other BLE equipment. I think the lowest I came across is 3 connections at the same time, and the highest is about 12-13 connections. These were limitations due to the hardware design and had nothing to do with the OS used. Typically, the limitation is that the hardware must track certain data and there is a limited amount of memory in the hardware.

So, I don’t know specifically for Android, but the OS-level limitation doesn’t make much sense. It is likely that when you try to establish a connection and you have reached the limit due to hardware, you should get some kind of error / exception preventing a new connection. I think that in fact there is a “connection restriction” error in Bluetooth, but some hardware provide other exceptions, such as “from resources”. Again, I'm not sure how this is reflected at the Android level.

Answer 4

I enter BLE development without any knowledge of Classic Bluetooth development, and I really don't know what “pair” means in BLE. Isn't that something that exists only in classic Bluetooth?

If you're talking about connecting when Android 4.3 first appeared, I did some tests on the SDK on Nexus 7 2013. The maximum number of devices that it can connect is 4 . I have not tested whether this number has changed in 4.4, but I can confirm that it will not be less than 4.

Answer 5

I work on a BLE device, can any of them be sure that the maximum number of connected active devices in the iPhone depends on the phone’s memory, for example, 32 GB → 7 BLE devices and 64 GB → 14 BLE devices. If yes, briefly, Thank you!