When update for Amp v4 is installed it erases all the settings for UART customization:
can this be set to remain permanent, because if any of my customers updade FW, setting will be lost and device will not work as intended
@zpl1025 any idea how settings can remain on upgrade?
E, I’ve actually considered for this, and have designed a set of APIs to save settings which would be kept after factory reset. It’s very rough and not tested too much, so did not announce yet, but it’s actually inside the firmware. You could try it out first and see if anything abnormal 
The commands also sent via the UART protocol, so you need to add MCU+PAS+RAKOIT: as prefix. And the following commands will send with prefix DEF:, for example, the command to set beep sound off by default MCU+PAS+RAKOIT:DEF:BEP:0&. And you need to save the settings after changes, and maybe take affect when you do factory reset.
"LTP", // API_SUB_MSG_LED_TYPE, // RGB/PIN/UND, set to PIN to control LED with each PIN, normally used on AMP and PRO board only.
"NAM", // API_SUB_MSG_DEVICE_NAME, // hexed string for real text, eg: 303132 for 012
"FXN", // API_SUB_MSG_FIXED_DEVICE_NAME, // [0,1] while set to 1, the device name will be restored when reset factor
"VOL", // API_SUB_MSG_VOLUME, // [0,100] set default volume.
"VBS", // API_SUB_MSG_VIRTUAL_BASS, // [0,1] set default VB state
"PMT", // API_SUB_MSG_PROMPT, // [0,1] set default prompting voice
"SEN", // API_SUB_MSG_SOURCE_ENABLE, // to disable some unwanted input sources. not working yet.
"POM", // API_SUB_MSG_POWER_ON_MODE, // appoint the input mode on boot
"VOS", // API_SUB_MSG_GROUP_VOL_SYNC, // [0,1] set default state for whether sync volume between master and slave devices.
"BEP", // API_SUB_MSG_BEEP_SOUND, // [0,1] set default state for beep key sound
"MDL", // API_SUB_MSG_MODEL_STRING, // hexed string, store a text, maybe used to identify device? not used for device itself.
"VST", // API_SUB_MSG_VOLUME_STEP, // [0,10] set default volume step
"SAV", // API_SUB_MSG_SAVE, // save default settings
That is great, I will teat it.
Most important is VOS *( group synchronized volume)
Can it be set to 1 by default too?
yes, you could have a try
Hi Frank, looks like VOS WORKS : THNX
is there a way to turn off promt voice at all ?