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+# Grbl (CNC Controller) For ESP32
+
+![ESP32](http://www.buildlog.net/blog/wp-content/uploads/2018/07/20180718_175943.jpg)
+
+### Status: Functional Beta (See issues below)
+
+
+
+### Project Overview
+
+This is a port of [Grbl](https://github.com/gnea/grbl) for the ESP32. The ESP32 is potentially a great target for Grbl for the following reasons
+
+- **Faster** - Faster step rates and additional features could be added
+- **Lower Cost** - 
+- **Small footprint** -
+- **More Flash and RAM** - A larger planner buffer could be used and more features could be added.
+- **I/O** - It has just about the same number of pins as an Arduino UNO, the original target for Grbl
+- **Peripherals** - It has more timers and advanced features than an UNO.  These can also be mapped to pins more flexibly.
+- **Connectivity** - Bluetooth and WiFi built in.
+
+### Issues / Changes
+
+1. **Startup Text** - Can we get rid of the ESP32 startup text? It might annoy some senders. It is probably possible using sdkconfig.h. but that might be difficult for the novice Arduino IDE user.
+2. **Direction pin delay** - Not implemented yet. Some drivers require a couple of microseconds after the direction pin is set before you start the step pulse. The original plan was to [use the RMT feature](http://www.buildlog.net/blog/?s=rmt), but that has issues when trying to use it in an Interrupt.
+3. **Step pulse off timing** - I am not getting accurate turn off times.  It never seems to change from about 2-3uSeconds.   It works well enough, but it should be user adjustable via $0 setting.
+4. **Step Idle Delay ($1)** - st_go_idle() is called from the interrupt, so there is no good way to put the delay there like AVR Grbl. I put the "delay" in the main protocol loop. It calls esp_timer_get_time() each time through to see if the time has passed.
+5. **Limit Switch debouncing** is not supported yet. It does not seem to be a problem on my test rigs. It might be better to us an R/C filter for now.
+
+### Using It
+
+The code should be compiled using the latest Arduino IDE. [Follow instructions here](https://github.com/espressif/arduino-esp32) on how to setup ESP32 in the IDE. The choice was made to use the Arduino IDE over the ESP-IDF to make the code a little more accessible to novices trying to compile the code.
+
+I use the NodeMCU 32S version of the ESP32. I suggest starting with that if you don't have hardware yet.
+
+For basic instructions on using Grbl use the [gnea/grbl wiki](https://github.com/gnea/grbl/wiki). That is the Arduino version of Grbl, so keep that in mind regarding hardware setup. If you have questions ask via the GitHub issue system for this project.
+
+### TODO List
+
+- RMT. The RMT feature is a ideal for direction and step features, but apparently has issues working in interrupts. See [this forum post](https://www.esp32.com/viewtopic.php?f=19&t=6397&hilit=grbl) and [this blog post](http://www.buildlog.net/blog/?s=rmt). It would be great to get it working.
+- Add spindle enable and direction.
+- Bluetooth - Add it so phones and PCs can use it to stream gcode. It would be great if it looks like a bluetooth serial port, that helps with compatibility with existing apps. ([Android Grbl Controller](https://play.google.com/store/apps/details?id=in.co.gorest.grblcontroller&hl=en_US) is best!)
+
+### Credits
+
+The original [Grbl](https://github.com/gnea/grbl) is an awesome project by Sungeon (Sonny) Jeon. I have known him for many years and he is always very helpful. I have used Grbl on many projects. I only ported because of the limitation of the processors it was designed for. The core engine design is virtually unchanged.
+
+### Contribute
+
+I would love to have help with this project. There are many things that need to be improved and added, especially BlueTooth and/or WiFi. If you need hardware to test with, I might be able to help with a test PCB.
+
+### FAQ
+
+Start asking questions...I'll put the frequent ones here.
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