1. Turn off Bluetooth power completely when using I2S, USB, Coaxial, Optical inputs.
2. Disconnect USB module completely  when using I2S, Bluetooth, Coaxial, Optical inputs.
3. Lower MCU and Flash frequencies to lower interference to the power rail.
4. Fix DPLL bandwidth setting bug (2026-7-25)
5. Fix the random volume decreasing bug (2026-8-15) 

Update methods:

Option 1 （recommended). Update via USB: Open MP-DX MK2 top cover, open ESP-Flasher.exe in Windows. 
Connect USB cable between Windows PC and front screen MCU board.

Option 2. Update via WIFI: Long press down rotary knob to access menu. Short press to navigate to  "WIFI F/W Update" in the screen menu option. Turn it on and wait about 1mins. On your computer WiFi settings, search for WIFI SSID name “MP-DX-OTA”, click on it to connect. The password is 123456789abc.  Once it is connected, open a browser, such as Chrome. Enter http://10.10.10.1 , it will open the firmware upgrade page. 
Choose the unzipped firmware upgrade .bin file. It should be finished in about 20-30 seconds. Don't power off during the upgrade process. MP-DX MK2 will reboot automatically. 


### 中文翻译
升级内容：
1. 使用I2S、USB、同轴、光纤输入模式时，彻底关闭蓝牙供电。
2. 使用I2S、蓝牙、同轴、光纤输入模式时，完全断开USB模块。
3. 降低单片机和闪存运行频率，进一步减少对电源轨道干扰。

升级方法：
方法1 (推荐）. **USB固件升级**：拆开MP-DX MK2设备上盖，在电脑端运行ESP-Flasher.exe烧录程序。用数据线将电脑与前面板主控板相连。需要有科学上网。
方法2. **无线网络固件升级**：长按旋钮进入菜单，短按切换至屏幕菜单里的**无线网络固件升级**选项并开启，等待约1分钟。
电脑无线网络搜索名为**MP-DX-OTA**的热点并连接，密码：123456789abc。
连接后打开谷歌浏览器，输入地址`http://10.10.10.1`进入升级页面。
选中解压后的固件bin文件上传，升级耗时20至30秒。升级期间切勿断电，设备会自动重启。