Controlling the Anker Soundcore P20i gaming mode (i.e., low latency mode) on Linux.

soundcore-p20i-gaming-mode.go

package main

import (
	"encoding/hex"
	"net"
	"os"

	"golang.org/x/sys/unix"
)

func main() {
	var cmd string
	if len(os.Args) > 1 {
		cmd = os.Args[1]
	}
	switch cmd {
	case "on", "1":
		cmd = "08ee00000001870b00018a"
	case "off", "0":
		cmd = "08ee00000001870b000089"
	default:
		panic("invalid command")
	}

	cmdBuf, err := hex.DecodeString(cmd)
	if err != nil {
		panic(err)
	}

	var mac string
	if len(os.Args) > 2 {
		mac = os.Args[2]
	}
	if mac == "" {
		mac = "F0:AE:66:B2:4E:95"
	}

	macAddr, err := net.ParseMAC(mac)
	if err != nil {
		panic(err)
	}
	if len(macAddr) != 6 {
		panic("invalid mac address")
	}
	macBuf := [6]uint8{macAddr[5], macAddr[4], macAddr[3], macAddr[2], macAddr[1], macAddr[0]}

	fd, err := unix.Socket(unix.AF_BLUETOOTH, unix.SOCK_STREAM, unix.BTPROTO_RFCOMM)
	if err != nil {
		panic(err)
	}

	// p20i rfcomm stuff is always on channel 10
	if err := unix.Connect(fd, &unix.SockaddrRFCOMM{Addr: macBuf, Channel: 10}); err != nil {
		panic(err)
	}

	f := os.NewFile(uintptr(fd), "bluetooth rfcomm "+macAddr.String())
	defer f.Close()

	if _, err := f.Write(cmdBuf); err != nil {
		panic(err)
	}
}

test.go

package main

import (
	"encoding/hex"
	"fmt"
	"net"
	"time"

	"golang.org/x/sys/unix"
)

/*
- adb root
- enable bluetooth
- enable bluetooth hci snooping in dev options
- disable bluetooth
- enable bluetooth
- do stuff
- adb pull /data/misc/bluetooth/logs/btsnoop_hci.log
- disable bluetooth hci snooping in dev options
- disable bluetooth
- enable bluetooth
- disable bluetooth
- wireshark
*/

func main() {
	mac, err := net.ParseMAC("F0:AE:66:B2:4E:95") // soundcore P20i
	if err != nil {
		panic(err)
	}
	addr := [6]uint8{mac[5], mac[4], mac[3], mac[2], mac[1], mac[0]}

	fd, err := unix.Socket(unix.AF_BLUETOOTH, unix.SOCK_STREAM, unix.BTPROTO_RFCOMM)
	if err != nil {
		panic(err)
	}

	// p20i rfcomm stuff is always on channel 10
	if err := unix.Connect(fd, &unix.SockaddrRFCOMM{Addr: addr, Channel: 10}); err != nil {
		panic(err)
	}

	fmt.Println("get device info")
	if buf, err := hex.DecodeString("08ee00000001010a0002"); err != nil {
		panic(err)
	} else if _, err := unix.Write(fd, buf); err != nil {
		panic(err)
	}

	{
		tmp := make([]byte, 98)
		n, err := unix.Read(fd, tmp)
		if err != nil {
			panic(err)
		}
		fmt.Println(hex.Dump(tmp[:n]))
	}

	fmt.Println("gaming mode off")
	if buf, err := hex.DecodeString("08ee00000001870b000089"); err != nil {
		panic(err)
	} else if _, err := unix.Write(fd, buf); err != nil {
		panic(err)
	}

	time.Sleep(time.Second * 5)

	fmt.Println("gaming mode on")
	if buf, err := hex.DecodeString("08ee00000001870b00018a"); err != nil {
		panic(err)
	} else if _, err := unix.Write(fd, buf); err != nil {
		panic(err)
	}
}