Update README.md

Author: scottbez1

README.md

@@ -10,10 +10,12 @@ Prototype four-character display: [video](https://www.youtube.com/watch?v=vq4o_8
 
 The goal is to make a low-cost display that's easy to fabricate at home in small/single quantities (e.g. custom materials can be ordered from Ponoko or similar, and other hardware is generally available).
 
-The 3d model is built using OpenSCAD in `3d/splitflap.scad`, the driver board is designed in KiCad in `electronics/splitflap.pro`, and the driver firmware is written using Arduino in `arduino/splitflap/splitflap.ino`.
+The 3d model is built using OpenSCAD in `3d/splitflap.scad`, the driver board is designed in KiCad in `electronics/splitflap.pro`, and the driver firmware is written using Arduino (with PlatformIO support) in `arduino/splitflap/Splitflap/Splitflap.ino`.
 
 You can view an interactive 3d model of the design on the [project website](https://scottbez1.github.io/splitflap/).
 
+**New:** Join the [community Slack group](https://join.slack.com/t/splitflap/shared_invite/zt-dpvol87b-3zUaxXrUd8WauPXr1uBj5Q) to discuss or ask questions about the project! (It's new so it may be a bit quiet, but don't be shy!)
+
 Want to help support prototyping and development?
 <a href="https://www.buymeacoffee.com/scottbez1" target="_blank"><img src="https://www.buymeacoffee.com/assets/img/custom_images/orange_img.png" alt="Buy Me A Coffee" height="22" ></a>
 
@@ -184,7 +186,7 @@ This generates gerber files and an Excellon drill file with Seeed Studio's [nami
 EESchema isn't easily scriptable, so to export the schematic and bill of materials `electronics/scripts/export_schematic.py` and `export_bom.py` start an X Virtual Frame Buffer (Xvfb) and open the `eeschema` GUI within that virtual display, and then send a series of hardcoded key presses via `xdotool` to interact with the GUI and click through the dialogs. This is very fragile but seems to work ok for now. For additional details, see this blog post: [Using UI automation to export KiCad schematics](http://scottbezek.blogspot.com/2016/04/automated-kicad-schematic-export.html).
 
 ### Driver Firmware ###
-The driver firmware is written using Arduino and is available at `arduino/splitflap/splitflap.ino`. 
+The driver firmware is written using Arduino and is available at `arduino/splitflap/Splitflap/Splitflap.ino`. 
 
 The firmware currently runs a basic closed-loop controller that accepts letters over USB serial and drives the stepper motors using a precomputed acceleration ramp for smooth control. The firmware automatically calibrates the spool position at startup, using the hall-effect magnetic sensor, and will automatically recalibrate itself if it ever detects that the spool position has gotten out of sync. If a commanded rotation is expected to bring the spool past the "home" position, it will confirm that the sensor is triggered neither too early nor too late; otherwise it will search for the "home" position to get in sync before continuing to the desired letter.