As part of my efforts to build a Matter powered dual temperature sensor, I was hunting for a Nordic nRF54L15 Module to use on my PCB.
I had already looked at the HolyIoT board with some success. Next on my list was the MinewSemi ME54BS01 module and dev kit.
This dev kit is very similar to the HolyIoT board and the modules are quite similar too. The modules I had both include an antenna and had castellated pins (for hand soldering)
The HolyIoT module has far more pins available, but they wrap around three edges.
I found the HolyIoT module didn’t have great support in KiCad, whilst MinewSemi had a nice symbol and footprint.
Some Assembly Required
Unlike the HolyIoT devkit, which came with the module installed, the MinewSemi DK needed a module.
I’m not much an expert in surface mounting components, but I had a go. Using my little MHP50 and some low temp solder paste, I mounted the board.
Some of the pins got shorted as the blobs melted together.
I used plenty of flux and ran my soldering iron across the pins, until all the pins were separated out.
With the board soldered on, it was time to flash some code onto it.
Flashing
I wired it up to my JLink programmer and switched on the 5V output. A blue light came on. Always a good start.
It also appeared as a device under the Nordic VS Code integration. Felt like something was working.
I then compiled the Blinky sample, from Zephyr and it even flashed on!
Unfortunately, nothing blinked. I hit reset. Nothing.
I figured it was my soldering. Maybe there was a short under the board? Maybe one of the connections wasn’t well made.
I posted some pictures to Reddit and the feedback was pretty clear. My soldering didn’t look great.
Mounting the board. Again.
I removed the board using my little hot plate.
There were clearly lumps of solder under the board. Using flux and copper ribbon, I cleared all the pads on the kit and module.
I decided not to use solder paste again. I need to get more precise with the application of paste. Instead, I used my soldering iron to solder the module in place.
This was a slightly better job!
Trying again
I powered it back up using the JLink 5V, but nothing happened 😟
I then plugging in the USB, wondering if that might help. The power light flickered briefly and my PC made a “USB connected” sound, but then nothing. I jiggled the USB connector. Nothing. Odd. Faulty board? I decided to come back to this USB problem
I was still wondering why the Blinky didn’t work. Perhaps the GPIO configuration for the Nordic DK was different from this board? I started looking for some overlay files for this board and I found this:
https://developer.blecon.net/board-reference/minew-me54be01
It seemed the board had UART for debugging, so perhaps that would give me a clue?
I followed the guide, plugging in my USB to TTL UART adapter (from my days of flashing Sonoff relays). Out of the blue, an LED started blinking.
I’ve no idea what happened. Aside from wriggling the USB connector and staring at the board, I did nothing else.
Regardless, it was working!
Summary
After two goes at soldering the MinewSemi module in place, I got the Zephyr Blinky sample to work!
This gives me confidence that when my custom PCB arrives, I’ll be able to solder the module into position.
I don’t understand why it didn’t start blinking immediately after I flashed and reset. Hopefully that’s just a glitch, or me being daft (did I really hit the reset button?)
I clearly need to improve my application of solder paste too. This seems like a less is more kinda situation. My custom PCB has a quite a few SMD components, so I need to improve!
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