Particle Boron UART RX/TX Specifications and Programming

Hardware
1

I'm looking at the Particle Boron datasheet for UART1_RX and UART1_TX which can also be used a digital GPIO. Where can I find the voltage/current specifications for these pins and learn to program them to communicate with a sensor?

Any documentation, schematics, and code are appreciated.

2

The RX/TX pins are the same as all other GPIO on all models of Boron if you do not enable UART serial. All GPIO is 3.3V, not 5V tolerant. Drive strength depends on software settings.

3

How do I enable UART serial? I haven't seen a specific enable UART line in the code that I have seen in other posts.

4

If you want to use it as a UART, use the Serial1 class.

If you want to use it as GPIO, use pinMode with the pin names RX and TX.

5

Thank you. Will the 3.3V UART function with 1.8V logic or do I need to use a level shifter?

6

You will definitely need a level shifter. From the I/O characteristics the input high level is 0.7 x 3.3 = 2.31V, so 1.8 is not high enough.

In the output direction direction, the 3,3V output will almost certainly be too high for a 1.8V device.