Add Spresense SDK 1.4.0

Signed-off-by: Kamil Tomaszewski <kamil.tomaszewski@sony.com>

README.md

@@ -1 +1,76 @@
-# spresense-micropython
+# Spresense exported SDK
+
+Prepared and exported Spresense SDK. To reproduce this, follow the steps below.
+
+## Step 1 - Clone Spresense SDK
+
+    $ git clone --recursive https://github.com/sonydevworld/spresense.git
+    $ cd spresense/sdk
+
+## Step 2 - Configure Spresense SDK
+
+Configure NuttX:
+
+    $ tools/config.py --kernel release
+
+Configure more with menuconfigkernel:
+
+    $ make menuconfigkernel
+
+Select:
+
+* `CONFIG_SYSTEMTICK_HOOK`
+
+Set:
+
+* `CONFIG_USEC_PER_TICK`=1000
+
+Configure sdk:
+
+    $ tools/config.py board/spresense feature/cmsis feature/dnnrt feature/gnss \
+    feature/imageproc device/adc device/camera device/charger device/pwm device/sdcard
+
+Configure more with menuconfig:
+
+    $ make menuconfig
+
+Deselect:
+
+* `CONFIG_NSH_BUILTIN_APPS`
+
+* `CONFIG_CXD56_SFC`
+
+## Step 3 - Modify Spresense SDK
+
+In file `nuttx/include/nuttx/compiler.h` (line 81) change
+
+    #if __cplusplus >= 201402L
+
+to
+
+    #if defined(__cplusplus) && __cplusplus >= 201402L
+
+In file `sdk/bsp/board/spresense/src/spresense_main.c` add function
+
+    void weak_function board_timerhook(void)
+    {
+    }
+
+## Step 4 - Build and export Spresense SDK
+
+    $ make buildkernel
+    $ make
+    $ make export
+
+## Step 5 - Extract Spresense SDK and change the name of the folder
+
+    $ unzip sdk-export.zip
+    $ mv sdk-export spresense-sdk
+
+## Step 6 - Rename files to be compatible with the NuttX repository
+
+    $ cd spresense-sdk
+    $ mv nuttx/include/arch/chip/cxd56_adc.h nuttx/include/arch/chip/adc.h
+    $ mv nuttx/include/arch/chip/cxd56_audio.h nuttx/include/arch/chip/audio.h
+    $ mv nuttx/include/arch/chip/cxd56_scu.h nuttx/include/arch/chip/scu.h
+    $ mv nuttx/include/arch/chip/cxd56_uart0.h nuttx/include/arch/chip/uart0.h