Create my owm design inspired by generic node se

HI all,
I would like to create my own design of Generic node se. I read this post and in the idea I would like to do almost the same thing. I want to keep antenna part. Just remove RFO_LP part.

What i would like to do :

  • Always use HP so I can drop U6B ?
  • Can I remove all components between RFO_LP and RF3 fromU7 ? Can I let RFO_LP pin floating ?
  • Just to be sure, the mode is selected from software if I want send or receive data that’s it ? By SUBGRF_SetSwitch from STM32WLxx-HAL_Driver

Thanks for your help

Do you want to be able to use the device for EU868? If so removing the low power output would be a bad choice as it increases power usage during transmission significantly without any gain in output power.

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Yes I want to use it for EU868. Could you explain me why it will increase power usage ? I’m newbie with STM32WL55 and Lora :blush:. There is a table somewhere where I can see power usage in different mode ?

So I have another question how the choice is done in the software for LOW or HIGH power and receive mode ? There is a specific function where FE_CTRL1/2/3 are used ?

Because the LP port uses a high efficiency power amplifier, the BOOST pin does not.

This is mentioned in the LoRa device datasheets, which if your designing a LoRa board with its own RF bits etc, is an essential cover to cover read.

Most, even experienced designers, would stay away from laying out their own LoRa board, it requires a fair bit of background and understanding of LoRa and RF stuff, plus a fair bit of fancy test equipment to make sure the impedance matching and harmonic surpression is adequate.

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Ok nice thanks for the explanations :wink:

So if I want to use EU868 maybe I can remove all parts of the line RFO_HP ?

If you only want to use EU868 that might be an option.

However, why not use an existing module like Seeeds Lora-E5 or a Rak one? A lot easier to integrate and less chance of failure.

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Yes it’s a good idea to use Seeeds Lora-E5 why not. I’ve also one question, my question is about R9, L15, L13 and L14, all these components are I supposed a filter. How values are calculated?

That is where

Comes into the discussion.

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Seeed Studio Wio-E5 is also only bringing the high-power output out. (Up to 22 dBm).
Using it in EU, you have to limit to 14 dBm.
For 14 dBm, it’s going to consume 45 mA (HighPower output) io 25.5 mA (LowPower output), according to the SX126x datasheet.
So this module is not optimal in terms of power efficiency for EU-868

Yes, they made that mistake, as did RAK. However, they got the RF matching right. Starting out from scratch is nice if you have an awful lot of time to waste and the right knowledge and equipment to get things right. And the drive to learn things by searching and trying, not by asking someone to help out every step of the way because there won’t be a lot of people here able to help.

Yup, we mourned those design flaws when it first came out. The RAK module has the same flaw/assumption too, however I believe the RAK SIP has resolved this.

It would be have been a smarter move by the Far East companies to create an efficient EU module, but the reality is that they created an easy to use STM32WL module at a (rapidly fluctuating) reasonable price. And I can place the Seeed module by hand on to a PCB, whereas having watched others trying to place BGA components, I know I’m not going to be very efficient at that. And I don’t have a tearing need right now to run out a few hundred at my CEM on their PnP machines.

So I’m happy to spend a little more on batteries for adhoc prototypes for the convenience of supply chain & manufacture.


@simon1 maybe I’m a bit late to the discussion, but would also like to give my opinion here:

  1. ST has released new ultra-miniature BALFHB-WL-0xD3 and BALFLB-WL-0xD3 BALUNs for their STM32WL series SoCs. Along with their complementary reference design for the High Band - Low Power option you can create really compelling design without having much RF knowledge on a 4-layer board.
  2. If you don’t want to design it from scratch, you can check out the MAMWLExx series modules from Move-X or RAK3172LP-SiP from Rakwireless, both of which are great options.

I’m curious which option you took/will take in the end.


In the mean time I have learned that both Seeed and RAK have 2 variants of their modules : one with the high power output and one with the low power output :

High-power version : Wio-E5 STM32WLE5JC lora module, embedded SX126X and MCU for LoRaWAN Wireless Sensor Network & IoT devices - EU868 & US915 - Seeed Studio

Low-power version : Wio-E5-LE Wireless Module (Bulk) - STM32WLE5JC, ARM Cortex-M4 and SX126x embedded, supports LoRaWAN on EU868 & US915-Seeed Studio - Seeed Studio

The RAK3172-SiP version does support up to 22dBm TX power.
RAK3172-SiP | STM32WL Module | LoRa-e5 Module | LoRaWAN SiP - LoRa SiP – RAKwireless Store

The RAK3172LP-SiP version is the low power version and supports only up to 15dBm TX power.
RAK3172-SiP | STM32WL Module | LoRa-e5 Module | LoRaWAN SiP - LoRa SiP – RAKwireless Store

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Jan 2024 ST released the STM32WL5MOC which can do both high power or low power.
Device needs to be configured in one of both modes by some bridges between some of it pins, or you can use a dc-switch for that.
Package is a LGA92 of 10x10mm.
It also looks like it has more GPIOs than the above modules.

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