Request for Hardware design guide for STM32WL33

[gusti_made]

Hello, I'm a beginner in hardware design for STM32 MCU wireless. I usually get detailed information about component value recommendations in the datasheet or application note. But in STM32WL33, I get unclearer information than in other MCU wireless documentation like STM32WL5 or STM32WB55. Here is the application circuit from the STM32WL33 datasheet; there is no component value recommendation. 

I have several question
1. what is L1 and L2 recomendation value?
2. I want to use this MCU for 433MHz or 868MHz, so what value recommendation for matching network components?

3. Why in the application circuit there is no RF switch? In AN5407 and MB1720 docs (STM32WL_QFN48_4Layers_Ref_Board) I found that using RF switch.

[STTwo-32 · Accepted solution]

Hello @gusti_made and welcome to the ST Community.

I've escalated your request internally to check for any recommendations from our experts (under internal ticket number 195557) and I will get back to you ASAP. For the third Question, The AN5407 is dedicated for the STM32WLE/5 not the STM32WL33.

Update: I can recommend you the following values for High band:

• L1 = 100nH
• L2 = 10uH
• Matching network for LPAWUR path:
  • L8 = 6.8nH
  • L10 = 5.6nH
  • C60 = 100 pF
• Matching network for external antenna:
  • C62 = 0.8 pF
  • C63 = 1 pF
  • L14 = 0R

And for Low band:

• L1 = 270nH
• L2 = 10uH
• Matching network for LPAWUR path:
  • L8 = 47nH
  • L10 = 5.6nH
  • C60 = 100 pF
• Matching network for external antenna:
  • C62 = 1 pF
  • C63 = 1 pF
  • L14 = 0R

Those values have been used on the Nucleo-WL33CC boards. All documentation that you need will be available soon.

Best Regards.

STTwo-32

[gusti_made]

Okay, thanks for the support. I have checked the Application note for STM32WB55 AN5165 it is explain so clear for beginner about component selection, layout, etc.

I also have another question: Where is the pin for SWO? It isn't mentioned in the datasheet.

[STTwo-32]

Hello @gusti_made 

First, The AN5165 is dedicated for the Low range 2.4GHz STM32WB products. That is different from the STM32WL33 series that works SUBGHZ frequencies. So, such application note may not be really helpful. 

For the STM32WL33, it is based on the Cortex-M0+. So, it does not implement the SWO.

Best Regards.

STTwo-32

[gusti_made]

Hello @STTwo-32 

Yes I know it not help, I just give example the Application Note that give clear information for begginers.
Okay I see, that Cortex-M0+ not implement the SWO.

Thanks