Gatttool: Limited to 5 connections?

Question

I connect to five devices creating gatttools with pexpect in python *. When I try to connect to the sixth device (using the same CSR 4.0 key for all connections) manually, I encounter:

sudo gatttool -b DC:05:4F:BC:F6:4A -It random [DC:05:4F:BC:F6:4A][LE]> connect Attempting to connect to DC:05:4F:BC:F6:4A Error: connect error: Too many links (31) 

Is this a gatttool limitation or a hardware limitation? I cloned the source at http://git.kernel.org/cgit/bluetooth/bluez.git and ran grep -r "attempting" but got no results.

I would like to connect to 20 low-energy bluetooth devices, which I think should be possible with hardware and firmware.

=====

System settings: Ubuntu 14.04, bluez v5.20, CSR 4.0, adafruit ble nrf8001.

Link :

• Using c files directly rather than pexpect: Multiple BLE connections using Linux and Bluez 5.0
• pexpect: https://gist.github.com/nouyang/2a6a733d8facd23115a4
• installation code description / pexpect: PYTHON → ADAFRUIT NRF8001 BLUETOOTH LOW ENERGY BREAKOUT IN 20 MINUTES

Answer 1

Oh! Someone from the linux-bluetooth list answered my question, although I have not yet confirmed it for myself:

This is a hardware CSR key restriction. I recently did a similar test using bluetoothctl: using a CSR key, only 5 Bluetooth devices can be connected. Using the Broadcom key (BCM20702), I could establish 14 concurrent connections. Then I ran out of Bluetooth Bluetooth devices ....

Regards, Martin Rösch

http://thread.gmane.org/gmane.linux.bluez.kernel/51872