How can we access PB0 alternate function RF_TX_MOD_EXT_PA to control external RF power amplifier?

[Dillah]

Hi,

I need a way to control external power amplifier enable to turn it on only when transmitting.

I read that PB0 has alternate function intended for this (RF_TX_MOD_EXT_PA).

Can I use this function to control the external amplifier SKY66118-11?

This is the tested external PA according to "STM32WB55 External PA integration and performances" document released by ST i 2019.

However SKY66118-11 has 2 control pin (CSD and CTX), while only PB0 is intended to control external PA.

Can I have the electrical connection for the testing? As it does not displayed in the document.

And also the FW scheme for the GPIO to control the external PA?

Thank You,

Muhammad ABDILLAH

[Remy ISSALYS]

Hello,

You can find information about this topic in AN5395 which explain the modifications to implement in the Cortex®-M4 firmware, to allow the external PA to be driven by the MCU.

Best Regards

[Dillah]

Hi Remy,

Thanks for the answer.

We implement the code following the application note.

The AN use PA0 for CSD, but we need to change it to PA1 because we use PA0 for other function already.

We were able to see the control signal for CSD as seen on below screen shot.

Unfortunately we still were not able to control PB0 pin for CTX.

I notice that this pin is dedicated for alternate function GPIO_AF6_RF_DTB0.

Is there any other thing need to be configured aside from the one stated in the AN?

Thank You

[Remy ISSALYS]

Hello,

As describe in the AN, there is nothing to do besides GPIO initialization and send the command SHCI_C2_ExtpaConfig in order to inform the Cortex-M0+ firmware on which GPIO must be managed. The CTX and CSD signals are managed by the BLE stack, only GPIO initialization is done on M4 side.

Best Regards