Librem 5 Breakout Board Projects

Has anyone here done any Librem 5 breakout board projects yet? I’ve been intrigued with this capability of the Librem 5 since reading about it.

The breakout capability does seem limited as it comes. There are only two GPIO pins on the breakout board, in addition to the serial communications pins. But with the connection of the right MCU to your circuit and to the I2C or serial port on the Librem 5 breakout board, you can have as many GPIO and other pins and analog/digital interface with the outside world as you want or need. Some MCUs come with multiple serial and I2C ports.

If you design-in an MCU it can come with the ability to talk to your Librem 5 via I2C or serial protocols, and can give you both digital and analog inputs and outputs, and an almost unlimited list of special functions. You just have to control everything from the Librem 5 through the I2C or serial bus. I work with MCU’s at work almost every day. But I don’t have my Librem 5 yet. I am looking forward to building some breakout board projects, just for fun when I get my Librem 5 and wanted to see if anyone here has any good ideas for breakout board projects. Mesh, LoRa, ham radio digital modes, analog applications, the sky is the limit.

The example in the article is a good one. But you probably don’t want a whole other Sparkfun board to support your main project board, all strapped on to the back of your Librem 5. You only want only one board, the one you design and layout. You could use the same IC
chips that Sparkfun used to do the level translation. I have a favorite one that seems to do everything I need.

Some of my MCU projects use level translation. I mostly use the 74LVC245PW for level translation. It’s an 8-bit bi-directional transceiver in a 24 lead TSSOP package. You can get the same transceiver in lower pin counts if you don’t need 8-bits, or stack several of them up if level shifting sixteen or thirty-two bits in parallel. Both sides of the transceiver go as low as 1.2V, up to 5.5V. There are voltage reference input pins on both sides. This one has a data direction pin that you control via a GPIO. If you need the data direction to be automatic, I know of a few that are similar but automatic. But I have never used those and can’t speak for how well they work.

Hopefully we can get some good discussion going here, about potential applications.

I haven’t used the breakout board yet, but I am trying to figure it out right now. I am following this guide to root my robot vacuum cleaner and install valetudo to control the robot from home assistant.

To root you have to connect GND, RX, and TX, which all are labeled on the breakout board. You also need to connect with 3.3 V.

Thus far I have connected the breakout board to the vacuum cleaner with three pins. I have not done anything in order to get 3.3 V, as I am not sure what to do. I have ran screen command for all the different devices under /dev/ like this

screen /dev/ttyUSB0 115200,ixoff

But screen is terminating. Is there anywhere I can read about how this breakout board can be used?

Edit: So I went into this with no knowledge. It looks like there are some ports called ttymxc0 which seems relevant. I am now testing with a RX/TX loopback to see if I can get the librem 5 to send something to itself

What article?

Probably this one.

Update on my little project: I got a connection going with

sudo screen /dev/ttymxc0 115200,ixoff

I previously also connected RX to RX and TX to TX, which was wrong.

1 Like

I tried connecting a NFC board ( to the L5 breakout board using I2C. I wasn’t able to get it working. I’m sure it was something I was doing wrong, but after trying for a few hours I gave up. The same NFC board worked fine connected to a Raspberry Pi using I2C although I was using a level translator with the L5 but not with the Pi.

The NFC board is a worthy project. I hope you’re successful at figuring out how to get it working on the Librem 5.

If you have access to an oscilloscope, you could view the data and clock lines for both the L5 and the pi, both on the same oscilloscope screen at the same time. If you can find a common signal to trigger the oscilloscope on, that’s even better.

1 Like

I don’t have access to an oscilloscope but I frequently think about buying one or even one of those simple logic analyzers. Now that I have an actual use for one, maybe I will look into buying one again.