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ST Micro produced a great new chip! And then they packaged it inside a 9x9 0.5mm BGA… I tried to produce a PCB for it, but the limits were too great (tiny?) for OSHPark.

And then ST announced two more packages - and one wasn’t a BGA! It has fewer pins, and isn’t available yet, but this time I could stay within OSHPark’s parameters.

This board gives a breakout for all the GPIO pins (except see below), as well as components for all the special purpose sections. Note, however, the board has not been tested! I will be posting the schematic and BOM soon!

Features

Apart from the actual STM32WLE5C chip, this board has the following features:

• The board is tiny! It is designed to be used standalone, or as a module for a larger board (uploaded soon!).
• The antenna is attached via a U.FL connector.
• The 32 MHz TCXO and support components are included, and wired to PB0 (sorry, not available on a header).
• The PE4259 RF switch and RF signal path components are included.
• Both Low and High TX power paths are supported with solder jumpers JP1 and JP2 - one MUST be chosen and soldered before powering on!
• There’s an FTDI header (with extra pins for Battery), although it only supports 3v3 instead of 5v. Note that the linked device only supports 50mA, which is fine unless you’re using TX/PA High!
• The GPIO breakout is to 2× 17-pin 0.05" headers, for GPIOs and special pins:
  • Port A is on its own header, assigned to the correct pin numbers (starting at pin 0 ). There are also jumpers to connect to the FTDI RxD and TxD;
  • Ports B and C are on a second header, also assigned to the correct pin numbers - they coincidentally(?) interleave!
  • Special purpose pins are brought out, and are next to relevant pins for easy jumpering:
    • BOOT0 is next to GND (recommended) and 3v3 ;
    • Batt is available for the Real Time Clock;
    • NRST is available, and next to JTRST for jumpering if desired (not necessary);
    • VDDA is next to 3v3 , or can be connected to a separate supply if desired;
    • PC14 and PC15 are brought out directly - but have PTH footprints for a 32.768kHz crystal and capacitors if desired (note that the long trace lengths will affect the capacitance required);
    • AntSw CTRL for the PE4259 is available - connect to any GPIO.
  • JTAG / SWD is brought out to a CS10 CoreSight connector - SMD, PTH and Pogo footprints are overlaid. Thus the board can:
    • Be programmed standalone by Pogo;
    • Have an SMD or PTH connector soldered on for development work;
    • Be fitted to a larger breakout board, with (more usable) 0.1" headers and STLink serial programmer.

I’m not sure if I can do this - so there’s only one way to find out!

And yes, this is version 2. I’ve swapped two pins - one was Open Drain… sigh. At least the re-spin has allowed me to add test points!

Many boards have JTAG on them, but not the actual JTAG connector. A common JTAG connector is the ARM CoreSight 10 (CS-10), with 2x5 pins at a 0.05" pitch.

You can solder a connector to the pads, especially if you’re going to be doing a lot of debugging with it. But sometimes you just want to flash a new program onto the board – the work of moments.

Enter the CS10 Pogo board! This has a place for a regular CS-10 connector (either SMD or THT, shrouded or bare) to which you connect the programmer with a normal cable. This connector is wired to another one with larger holes for Pogo pins.

If you solder this near the bottom of the Pogo pin shafts (be careful not to actually solder the spring pogo!), then there’s still not much structural strength for the assembly. That’s why there’s a smaller, snap-off board to solder to the top of the shafts.

I’ve been debugging an STM32L432KC interfacing to a WIZnet W5500 on breadboards for a while now.

Every once in a while it does weird things, and I’m worried it’s because the breadboard wiring isn’t quite making contact - but that may just be a programmer blaming the hardware!

This board will put my excuses to rest - or fix the problem…

Edgar Allan Poe’s “The Raven” describes purple curtains.

This is a purple PoE-powered puller for curtains!

See my blog for BoM and other details.