How to enable Murata Bluetooth on VisionSOM-6ULL

How to enable Murata Bluetooth on VisionSOM-6ULL

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Configuring device tree to enable UART5 interface for Murata Bluetooth

Murata 1DX requires UART interface with RTS and CTS lines and one GPIO reset line for Bluetooth part. On VisionSOM-6ULL you should apply this configuration in the device tree (details on modifying device tree are available in How to customize Debian 9.2 device tree article):

...
                pinctrl_uart5: uart5grp {
                        fsl,pins = <
                                MX6UL_PAD_CSI_DATA00__UART5_DCE_TX      0x1b0b1
                                MX6UL_PAD_CSI_DATA01__UART5_DCE_RX      0x1b0b1
                                MX6UL_PAD_CSI_DATA02__UART5_DCE_RTS     0x1b0b1
                                MX6UL_PAD_CSI_DATA03__UART5_DCE_CTS     0x1b0b1
                        >;
                };

                pinctrl_bt: btgrp {
                        fsl,pins = <
                                MX6UL_PAD_CSI_MCLK__GPIO4_IO17          0x17059 /* BT reg enable */
                        >;
                };

...
...

&uart5 {
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_uart5>;
        fsl,uart-has-rtscts;
        dma-names = "", "";
        status = "okay";
};
...

Downloading firmware

Now you need to download firmware for Bluetooth module and place it in /etc/firmware directory (note that download link may change in the future, you can find it in documentation section on VisionSOM-6ULL Wiki page:

root@somlabs:~# cd ~
root@somlabs:~# wget http://ftp.somlabs.com/visionsom-6ull-bcmfirmware.tar.xz
root@somlabs:~# tar xf visionsom-6ull-bcmfirmware.tar.xz
root@somlabs:~# cp -R ./lib/firmware /etc/
root@somlabs:~# rm -R ./lib

Enabling Bluetooth

To enable Bluetooth first you need to reset and attach the module:

root@somlabs:~# echo 113 > /sys/class/gpio/export
root@somlabs:~# echo out > /sys/class/gpio/gpio113/direction
root@somlabs:~# echo 0 > /sys/class/gpio/gpio113/value
root@somlabs:~# sleep 0.1
root@somlabs:~# echo 1 > /sys/class/gpio/gpio113/value
root@somlabs:~# hciattach /dev/ttymxc4 bcm43xx 3000000 flow -t 20
bcm43xx_init
Set Controller UART speed to 3000000 bit/s
Flash firmware /etc/firmware/1DX_BCM4343W/BCM43430A1.1DX.hcd
Set Controller UART speed to 3000000 bit/s
Device setup complete

Now you need to install rfkill tool and disable rfkill block for Bluetooth:

root@somlabs:~# apt install rfkill
Reading package lists... Done
Building dependency tree
...
...
Setting up rfkill (0.5-1+b1) ...
root@somlabs:~# rfkill list
0: phy0: Wireless LAN
        Soft blocked: yes
        Hard blocked: no
1: brcmfmac-wifi: Wireless LAN
        Soft blocked: yes
        Hard blocked: no
2: hci0: Bluetooth
        Soft blocked: yes
        Hard blocked: no
root@somlabs:~# rfkill unblock 2
root@somlabs:~# hciconfig hci0 up

Now we can check if Bluetooth works:

root@somlabs:~# hcitool dev
Devices:
        hci0    43:43:A1:12:1F:AC
root@somlabs:~# hcitool -i hci0 scan
Scanning ...
        XX:XX:XX:XX:XX:XX       iPhone (XX)