LTE Cat M1/NB-IoT Shield Can't Communicate Over Serial

Wireless & IoT Cellular
1

I have an LTE Cat M1/NB-IoT Shield that I’ve connected to a Arduino Mega 2560 as a breakout. Pins 5, 6, 8, and 9 are connected from the shield to their respective pins on the Mega, and I’ve tested continuity on everything. I have the IOREF jumper set for 5v logic, and I have the switches set to have the shield get power from the Arduino, and software serial.

Whenever I load any of the example sketches to the Arduino, though, it never gets past “Initializing the shield… it make take 25/5 seconds.” The serial passthrough example also, unsurprisingly, doesn’t run.

Am I missing something here? Or is my shield just not communicating over serial? I have tried it with hardware serial as well, but with the same results. Also, it seems like the library doesn’t ever tell you communication has failed, because I get the exact same behavior when there’s literally nothing connected to the Arduino but a USB cable to my laptop, unless I’m missing something there too.

Any help or guidance would be greatly appreciated! I’ve attached a picture of my setup.

IMG_20200211_203552.jpg
IMG_20200211_203552.jpg1512×1134 664 KB

2

Hi floatingskull.

Unfortunately due to design considerations in the Mega, you can’t use the LTE Cat M1/NB-IoT Shield with a Mega without making changes to the board and libraries. We suggest using [stackable headers as detailed in the [hookup guide on the shield and connecting it to an Arduino Uno or Uno clone like our [RedBoard.

One note if you use stackable headers: Clip off the pin on the AREF pad so that it doesn’t connect to AREF on the Arduino. See the hookup guide for the reasoning behind this.](https://www.sparkfun.com/products/13975)](LTE Cat M1/NB-IoT Shield Hookup Guide - SparkFun Learn)](https://www.sparkfun.com/products/11417)