Karl | Oct. 31, 2019

Great Development Board

For Grasshopper LoRa/LoRaWAN Development Board

The documentation was somewhat difficult to go through, but we were able to get the functionality we needed to work. I had an issue with the module not being picked up over usb, but I got a quick response how to solve that. Just exit Arduino, plug in the kit to usb, hold the boot button, then press the reset button. Overall, the examples were great and this module was a really great way to jump right into LoRaWAN for an absolute beginner like me. The LoRaWAN_Callbacks sketch has an example a of downlink for those that may have spent a few minutes longer than they should have trying to find that example.

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Response from Tlera Corp | Oct. 31, 2019

Glad you were able to make this work for you. Our goal is to make the Grasshopper development board easy to use but I agree we could do better on the documentation. Still, we hope programming via USB using the Arduino IDE outweighs whatever documentation deficiencies remain. The CMWX1ZZABZ-078 module is quite capable and the examples are there to help you get started. Just let us know if you have any trouble by sensing e-mail to tleracorp@gmail.com.

Stefan | Oct. 14, 2019

Works fine but but has some caveats

For SDIO Card Reader for Dragonfly

I purchased the SDIO card because it is the only 4 bit solution for STM32L4 (apart from the ST eval board) and has short data lines and easy access for a logic analyzer. I was not interested in the Arduino stuff although I looked into the arduino core code out of interest.
Positive:
-short data lines to SD-card which enables the use of high clock frequencies.
-decoupling caps on board
-Arduino core code has been programmed natively on the sdmmc register interface so no ST HAL. Very impressive and I suppose a lot of time was spent on this.

Possible improvements:
-mounting on the Dragonfly. To avoid covering the RGB-LED it has to be mounted on the bottom, but in this case access to the sd card is really cumbersome
-no pull-ups on CMD and data lines. You have to rely on setting the internal STM32 pull-ups
-D3 is connected the blue part of the RGB LED and the is no solder bridge. This imho is a poor choice signal integrity wise and power consumption wise

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Response from Tlera Corp | Oct. 14, 2019

Thanks for the detailed review Stefan!

This is a small board with a fair number of peripherals so some trade-offs had to be made in the design. We agree having the rgb led share other pin functions is undesirable, but it is the choice we made. As far as power usage, SD cards are high-power devices, which is one reason the SD Card Reader interface design for the Dragonfly seems somewhat of an after thought; it was! Nevertheless, we have found that it can work well despite the awkward access to the SD card itself.

Christopher | Oct. 14, 2019

Amir | Aug. 14, 2019

Mike | July 5, 2019