STM32WE5 SubGHz_Phy Middleware Questions

[JesusAVC]

Hello everyone

We are developing a prototype of vibration monitor system . Now we are in optimization stage , reducing the power of the device . We are using SeedStudio Lora E5 HF (STM32WE5) (US915) https://files.seeedstudio.com/products/317990687/res/LoRa-E5+module+datasheet_V1.0.pdf  , and programing it using STM32CubeIDE and this code base https://github.com/Seeed-Studio/LoRaWan-E5-Node/tree/qian. 

Our target is to reduce the tx power . However there's many configuration around that and it's not clear the final dBm . This module can give up to 22dBm on TX according to the specs . We would like to reduce it to 6dBm to save power .

Right now I'm playing around with SUBGRF_SetTxParams function and I was able to see a change in current consumption when the device is transmitting .

But still having some these questions :

1. How can I calculate or know what is the final dBm ? to achieve the 6dBm
2. Using this official middleware guaranteed the FCC certification or should we pass the certification process again ? 

Thanks in advance

[ahsrabrifat]

Modify the function call to use Low Power PA (RFO_LP) and to Set TX power to 6 dBm

The corrected Function Call has to be like this.

SUBGRF_SetTxParams(RFO_LP, 6, RADIO_RAMP_40_US);

[JesusAVC]

Thanks for the reply

I would like to  understand.According to the function documentation

the range is -18dbm to 13dbm . However my radio specs say it can support 22dbm TX (US915)

Is this a Gain/attenuation to be applied to the total 22dbm ? .

Is RFO_LP 14dbm  and RFO_HP 22dbm ?

How can I have a estimated practical value ? I mean 6dbm should give me TX current of 20mA  @3.3V ?. By default I get around 110mA

I want to limit the final TX  power to 6dbm.