Imx6ul Bluetooth
| Note: | The latest image for this platform as of April 28th, 2022 has known issues with the Wi-Fi driver and BLE coexistence due to incompatibility with cfg80211 powersave modes.
If using both Wi-Fi and BLE, it is strongly recommended to bring up the Wi-Fi interface, and then run This issue will be addressed in future images and has already been addressed in our kernel sources. We will continue to provide updates as we receive them from the Wi-Fi module manufacturer. |
The Wi-Fi option for this platform also includes a Bluetooth 5.0 LE module. Support for Bluetooth is provided by the BlueZ project. BlueZ has support for many different profiles for HID, A2DP, and many more. Refer to the BlueZ documentation for more information. Please see our BLE Examples page for information on installing the latest BlueZ release, getting started, and using demo applications.
Both Wi-Fi and Bluetooth can be active at the same time on this platform. Note however, that either the Wi-Fi interface needs to be not brought up if Wi-Fi is unused, or it needs to actively connect to an access point or act as an access point. The Bluetooth module can be activated with the following commands:
For Bluez versions found on Debian Stretch and below:
# Enable Bluetooth, and load the firmware
echo BT_POWER_UP > /dev/wilc_bt
sleep 1
echo BT_DOWNLOAD_FW > /dev/wilc_bt
sleep 1
# Attach the BLE device to the system, increase the baud, and enable flow control
hciattach /dev/ttymxc2 any 115200 noflow
sleep 1
hcitool cmd 0x3F 0x0053 00 10 0E 00 01
stty -F /dev/ttymxc2 921600 crtscts
# Note that no other HCI commands should be used! In older versions of BlueZ, HCI commands exist alongside bluetoothd, however HCI commands can interfere with the bluetoothd stack.
For newer versions of BlueZ found on Debian Buster or newer, or newer versions of BlueZ built from source:
echo BT_POWER_UP > /dev/wilc_bt
sleep 1
echo BT_DOWNLOAD_FW > /dev/wilc_bt
sleep 1
btattach -N -B /dev/ttymxc2 -S 115200 &
sleep 1
bluetoothctl power on
sleep 1
hcitool cmd 0x3F 0x0053 00 10 0E 00 01
kill %1 # This terminates the above btattach command
sleep 1
btattach -B /dev/ttymxc2 -S 921600 &
At this point, the device is running at 921600 baud with flow control, and is fully set up ready to be controlled by various components of BlueZ tools. For example, to do a scan of nearby devices:
bluetoothctl
power on
scan on
This will return a list of devices such as:
root@ts-imx6ul:~# bluetoothctl Agent registered [CHG] Controller F8:F0:05:XX:XX:XX Pairable: yes [bluetooth]# power on Changing power on succeeded [CHG] Controller F8:F0:05:XX:XX:XX Powered: yes [bluetooth]# scan on Discovery started [CHG] Controller F8:F0:05:XX:XX:XX Discovering: yes [NEW] Device 51:DD:C0:XX:XX:XX Device_Name [NEW] Device 2A:20:E2:XX:XX:XX Device_Name [CHG] Device 51:DD:C0:XX:XX:XX RSSI: -93 [CHG] Device 51:DD:C0:XX:XX:XX RSSI: -82 [NEW] Device E2:08:B5:XX:XX:XX Device_Name [CHG] Device 51:DD:C0:XX:XX:XX RSSI: -93 [CHG] Device 2A:20:E2:XX:XX:XX RSSI: -94 [NEW] Device 68:62:92:XX:XX:XX Device_Name [NEW] Device 68:79:12:XX:XX:XX Device_Name [bluetooth]# quit
Please note that the Bluetooth module requires the modem control lines CTS and RTS as flow control when running at higher baud rates. It is possible to run the module at the initial 115200 baud if the flow control lines are unwanted.
The module supports some other commands as well:
# Allow the BT chip to enter sleep mode
echo BT_FW_CHIP_ALLOW_SLEEP > /dev/wilc_bt
# Power down the BT radio when not in use
echo BT_POWER_DOWN > /dev/wilc_bt