I've put together a program that times a sprint contest on bicycles (a training aid for BMX racing). I have no problem getting the resulting times to display on my laptop via the USB and had moved on to the task of getting the numbers to a simple display so the whole thing could be mounted in a box. I bought a I2C, 2 x 16 LCD display off Amazon and despite reading some dicey reviews thought I could get the hardware in, hook it up, get the "Hello World" example script running and proceed from there.
I've had 0 luck with this despite having tried the provided libraries, libraries from other sources, different addresses for the I2C expander, etc..
What I'm looking for is a recommendation on a reliable supplier of hardware (and libraries to support their hardware).
The requirements are simple, 2 lines of numeric display in the format "00.000". I'd even be fine with 2 old school multi-segment LED displays at this point.
Thanks in advance for letting me in on your collective experience.
These work very well for me, good sale price right now:
I've also used these, they're also fine, interchangeable with the one above and a little less expensive:
Both work fine with the standard LiquidCrystal library, as well as with some improved versions that are out there. To convert them to I2C, these work well:
If this doesn't get you up and running, please provide some more details on the I2c module and display, as well as what specific problems you are having. Which model of Arduino are you using?
It's possible you have defective hardware, but if so, there are typical patterns of failure that will show on the display.
Adafruit's library works with the MCP23008 I/O expander (as used in their backpacks) and FMalpartida's library works with the PCF8574 expander (as used in backpacks from electrofunltd.com), so the libraries are not interchangeable in that regard.
I benchmarked several libraries in native and in I2C mode (MCP23008); results and code are here.