SARA-R410M not responding to commands

Wireless & IoT Cellular
1

Hello,

I’m running into issues with my " LTE CAT M1/NB-IoT Shield - SARA-R4" board. I wanted to use it as an external shield. It’s powered of USB+LiPo.

I did some basic testing with a direct serial connection. Once I got it to the point (via manual AT comments) to connect to the Hologram network. I moved over to my microcontroller to integrate it. It worked fine for a bit, but I got some really weird behavior. After spending many hrs swapping libraries, and building more basic sketches to test functionality, I think I have come to the conclusion the unit has stopped responding to serial commands. Curiously, it’s still connecting to the network and responding to the PWR and RST switches.

At this point it’s back to being a standalone board. But I get zero output from it in any way.

Thoughts?

Bas

2

It sounds like you might have a defective board; I found your order…we’ll be sending out a replacement unit ASAP!

1 Like
3

Hi, received the replacement board. And I have yet to get a single response from it :frowning: I did a lot more reading since the first board, and discovered that it can be:

  • Very sensitive to supply power issues
  • Can get in a corrupt state if powered off while connected

So I’ve been extremely careful with this new board:

  • Powered ONLY with a battery, or battery + USB so that the battery provides voltage buffering
  • Make sure to always power down the unit before removing power

I have a high quality Serial adapter (Voltlink) for my connections
I have used my microcontroller to check that both RX and TX wiring from my Voltlink to the modem modules is working

When I power the module on, I give it some time before sending AT commands since the manual says you should.

Are other people using this board successfully?

Is the other Ublox module much better? Should I just give up on the R410 module? The fact it’s so sensitive to supply voltages and can get into an uncoverable state from hard shutdown make it not a great module to use. But I only found this after lots of reading and searching for my specific issue. I have no idea if the other Ublox module is better.

The R410M is supposed to provide a logic high (1.8V) on the V_INT pin when it’s ready to go. The sparkfun board seems to have this pin tied to the 1.8V rail instead. Not broken out to a pin or testpoint?

Any and all feedback welcome. There is not a lot of lower power LTE boards available it seems :frowning: So I’m kinda stuck with these :slight_smile:

Bas