I when I tried to create a new gecko "Bluetooth In-place OTA DFU" bootloder for EFR32BG22C224F512IM40 device in Simplicity studio I discovered that not able to select any EFR32xB22 device in the list of available devices for that bootloder type. Does it mean that this boatloader type is not suported got EFR32XG22 device family?

Here is few print-screens from the project creation:

1. Stack selection:

2. Application type selection:

3. Device selection

If so, is there any other similar bootloder type I can use for this device without the necessity to reserve inside the device FLASH memmory a slot with size of about the half of the available FLASH memmory for the firmware image update?

It seems that I will need more than 300 kB for the Bluetooth application itself, soI am not able to create a seperate slot in internal FLASH for the firmware update.

Which version of IAR ide you are using.

have you tried to use the pack manager to update the IAR to support EFR32BG22.

When I try to open in the IAR IDE a firmware project generated in Simplicity Studio for EFR32GB22 device I see a warning message saying that the corresponding device description file "EFR32BG22C224F512IM40.ddf" for debugger is missing. And it is probably also the reason why I am not able to run the debug session in IAR IDE when the firmware is compiled.

Please could you advice if this device description file for IAR IDE is already available and where it is possible to get it?

Yes. The application is also monitoring voltage of a build-in Lithium battery - it is that VBAT voltage. In that case the internal 2.5V reference is used.  The purpose of battery voltage monitoring is to have an information about battery state. Based on the measured battery voltage we can estimate the remaining battery capacity (it is not precise, but it provides at lease some estimation), indicate it to the user and switch the application to a low power (shutdown) mode if the battery is too low.

I think that we can not use VMON for this purpose as it is just a comparator and it does not provide possibility to monitor external voltage, just the internal one. Am I right?

Attached is the corresponding part of schematics with slider potentiometer connection. The potentiometer has resistance of about 10 kohms and it is activated by Q2 only during the measurement period to save the battery power. Since it is connected between VDD (+2.8V) and GND the ADC result should not be influenced by VDD variation.

So far it works well. The only issue is that uncompensated ADC gain error in this configuration.