Created Building Micropython Binaries (markdown)

Building-Micropython-Binaries.md

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+This describes the basics on building micropython binaries for different boards. In the examples below all builds were done on a Linux Mint 18.0 machine.
+
+Prerequisites to this are setting up your build environment. You can [get started and setup your build environment on Linux Mint 18.0 here](https://github.com/micropython/micropython/wiki/Getting-Started---Compiling-Micropython-for-Ubuntu-16.04)
+
+Assuming that you have a working environment and you can run **make** to make a build for Linux we can now:
+* directory structure
+* making a build for an architecture
+* identify the firmware builds
+* flashing onto micropython hardware
+
+## Directory Structure
+Building micropython for different hardware happens in the **ports** directory. If you look in:
+```bash
+  ~/microPython/project/micropython/ports
+```
+This contains a list of hardware platforms that are supported. At the time of writing, 14 in total. This document describes how to build for stm32 - the platform used by the micropython organisation. Which is in the stm32 subdirectory:
+```bash
+  /ports/stm32
+```
+
+Within each platform directory there is build<name> directory e.g.
+
+```bash
+ /ports/stm32/build-PYBD_SF2
+ /ports/stm32/build-PYBD_SF6
+```
+When a build is complete the firmware builds are placed in the relevant directory. Within a build directory there are two main build files that are used to flash onto a board. Which are named **firmware.hex** and **firmware.dfu*. The *dfu* file is the file that has to be flashed onto your microcontroller.
+
+Within the stm32 directory there is a **modules** directory. This is used to compile your own modules into a firmware build. This is explained later.
+
+## Making A Build For An Architecture
+To make a build for a particular architecture you have to be in the specific hardware directory to run the make command. The **make** command can take many parameters, this document looks at building for a particular board and compiling into the firmware your own modules.
+
+The format of the build command is **make** then **[option]** then **[target]**. For compiling against the new [pyboard D-series](https://store.micropython.org/category/pyboard%20D-series) the build targets are:
+* PYBD_SF2
+* PYBD_SF4
+* PYBD_SF6
+
+Hence you would comple for the [SF2](https://store.micropython.org/product/PYBD-SF2-W4F2) like:
+```bash
+   /> make BOARD=PYBD_SF2
+```
+And for the SF6 it would be:
+```bash
+   /> make BOARD=PYBD_SF6
+```
+
+### Compiling Your Own Python Code Into Firmware
+To make a firmware build with a python file that you have created, simply place in the **/modules** directory the python file you wish to be available in your firmware build. Hence if you wanted to have a **hello_world.py** compiled into your firmware image do: 
+- place the **hello_world.py** into your /ports/stm32/modules directory
+- do your buld with the command **FROZEN_MPY_DIR=modules
+
+e.g.
+```bash
+   /> make BOARD=PYBD_SF2 FROZEN_MPY_DIR=modules
+```
+
+
+
+