[Android Head-Units] shanetrainST:
I think Joying are using the init.connectivity.rc file to control the bluetooth states.

This could explain why the Bluetooth is hidden away from all other applications.

I use a app called SpeedyBee to talk to my racing drone via BT, this app work on nearly every android device I have, I will use this a test app to see if I can edit the .rc file to allow the app access to the BT.

**EDIT NEW**

I did try to replace the init.connectivity.rc file with bit and pieces of another one i found.

specifically adding the device address and removing the FYT junk

https://github.com/Nu3001/device_rockchip_rksdk/blob/master/init.connectivity.rc

But Android 8.0 just overwrote the file?? back to the original, I even had the CHMOD correct at 750 on the new init.connectivity.rc and I renamed the old one to nit.connectivity.rc.old

Here is content of the latest joying PX5 rom.

on boot

# for bluetooth

# change back to bluetooth from system

chown bluetooth net_bt_stack /data/misc/bluetooth

mkdir /data/misc/bluedroid 0770 bluetooth net_bt_stack

# bluetooth LPM

chown bluetooth net_bt_stack /proc/bluetooth/sleep/lpm

chown bluetooth net_bt_stack /proc/bluetooth/sleep/btwrite

# insmod /system/lib/modules/rtk_btusb.ko

chmod 0660 /dev/rtk_btusb

chown bluetooth net_bt_stack /dev/rtk_btusb

# bluetooth MAC address programming

chown bluetooth net_bt_stack ro.bt.bdaddr_path

chown bluetooth net_bt_stack /vendor/etc/bluetooth

chown bluetooth net_bt_stack /data/misc/bluetooth

setprop ro.bt.bdaddr_path "/data/misc/bluetooth/bdaddr"

chmod 0660 /dev/vflash

chmod 0664 /dev/vendor_storage

chown bluetooth net_bt_stack /dev/vflash

chown bluetooth net_bt_stack /dev/vendor_storage

chmod 0666 /dev/tty*

chmod 0666 /sys/fytver/*

chown bluetooth net_bt_stack /sys/class/rfkill/rfkill0/type

chown bluetooth net_bt_stack /sys/class/rfkill/rfkill0/state

chmod 0664 /sys/class/rfkill/rfkill0/state

# for wifi

# mt7601u

# chmod 0644 /system/lib/modules/mtprealloc7601Usta.ko

mkdir /data/misc/wifi 0770 wifi wifi

mkdir /data/misc/wifi/sockets 0770 wifi wifi

mkdir /data/misc/wifi/sockets/tmp 0440 wifi wifi

mkdir /data/misc/dhcp 0770 dhcp dhcp

chown dhcp dhcp /data/misc/dhcp

mkdir /data/misc/wifi 0770 wifi wifi

chmod 0660 /data/misc/wifi/wpa_supplicant.conf

chmod 0660 /data/misc/wifi/p2p_supplicant.conf

mkdir /data/misc/wifi 0770 wifi wifi

mkdir /data/misc/wifi/sockets 0770 wifi wifi

chmod 777 /data/misc/wifi/sockets

mkdir /data/misc/wpa_supplicant 0770 wifi wifi

chown wifi wifi /data/misc/wifi

chown system wifi /data/misc/wifi/entropy.bin

chown wifi wifi /sys/module/bcmdhd/parameters/firmware_path

chown wifi wifi /data/misc/wifi/p2p_supplicant.conf

chown wifi wifi /data/misc/wifi/wpa_supplicant.conf

#for nfc

chmod 0660 /dev/bcm2079x

chown nfc nfc /dev/bcm2079x

mkdir /data/nfc

mkdir /data/nfc/param

chmod 0700 /data/nfc

chmod 0700 /data/nfc/param

chown nfc nfc /data/nfc

chown nfc nfc /data/nfc/param

service wpa_supplicant /vendor/bin/hw/wpa_supplicant \

/vendor/etc/wifi/wpa_config.txt

class main

socket wpa_wlan0 dgram 660 wifi wifi

disabled

oneshot

service wifiservice /vendor/bin/wifiservice

class main

user root

disabled

oneshot

service btservice /vendor/bin/btservice

class main

user root

disabled

oneshot