configuration :
power by external adapter on arduino 5v + gnd pins
rx sara - rx serial usb ( i reversed this as well rx - tx)
tx sara - tx serial usb ( i reversed this as well tx - rx)
vin sara - vcc serial usb
gnd sara - gnd serial usb
power switch arduino (i reversed this as well arduino - shield)
baud rate: from 9600 to 115200
expected results: communication over serial port
actual result : nothing in serial port
serial port works when connected to other serial devices
Hi stoikos,
I am a bit confused by your description of your circuit. There are multiple serial pins available on the LTE CAT M1/NB-IoT Shield so can you please specify which ones you are using with either a circuit diagram or photos of your connection? For example, are you using the FTDI header or the “Arduino” serial pins tied to the Serial switch? Also, your serial lines are mixed. You need to pair RX with TX and vice versa. If you connect RX to RX and TX to TX there will be no data being sent or received by either the SARA-R4 or your USB to Serial device. Finally, make sure you are actually turning the SARA-R4 module on by pressing the POWER button next to the module. If you have not read through it yet, I would highly recommend reading our [Hookup Guide for this shield as there is a lot going on with it and it is easy to make mistakes with your wiring if you are not using it as an Arduino shield.](LTE Cat M1/NB-IoT Shield Hookup Guide - SparkFun Learn)
Hi TS-Mark,
I am using the ftdi header (pins called rx-arduino, tx-arduino , ioref). I did try both combinations before i post this message (tx-tx,rx-rx and tx-rx,rx-tx) . I did go over your hookup guide multiple times, the posts in this forum (actually initially i thought that the issue would go away if i power the shield from an independent source) and read all the comment in the product page . I did press the power for over 3 sec and also. I did press the reset button for over 10 sec in an attempt to do a factory reset. During all this time I have used an activated tmobile nano sim card. I will try to see if the usb interface works, although in my use case i need serial connection with arduino. Any ideas? if you still need pics of the wiring i can send you some
after factory reset it worked
Hi again stoikos,
Interesting. I wonder if that port was disabled somehow. I hope you did not lose too much progress when you restored the SARA-R4 to factory settings but I am glad to hear that it is working properly now!
Let us know if you have any other questions or concerns about this shield and we would be happy to help as much as we can.
