Hi!
We are developing an ultralight, ultra low power IoT device and the STM32WL seems like a great fit.
We have chosen the STM32WLE5CCU variant (M4 MCU, 256kB, UFQFPN-48) because we don’t need the extra processor core. When designing the board, I ran into a couple issues.
- No matter how hard I looked, there seem to be no dev boards or even reference designs for the STM32WLE variant whatsoever. So far I’m following the STDES-U4S reference design. Is this correct? Is all the clock and RF stuff the same?
- Looking at the reference schematic, there is a lot of RF related components. Our application needs to reduce component count as much as possible because of size. Previously, we have used a Semtech SX1276 LoRa transreceiver. There, we dramatically reduced the component count by using the FI168B0845D9-T bandpass filter in a single ceramic package. I’m trying to see where could I place this.
Looking at the reference schematic, this section seems to be the bandpass filter, is it possible to replace it with the component I mentioned? I asked an RF engineer, he said it’s impossible to recalculate the component values since ST doesn’t provide the pin impedance specs which would be required for this. Does this mean I’m stuck using the reference design?
Thanks.
