Add "board_f_flash" option to Project Configuration File // Resolve #501

docs/platforms/espressif_extra.rst

@@ -9,19 +9,33 @@
     See the License for the specific language governing permissions and
     limitations under the License.
 
-Custom CPU Frequency or Upload Speed
-------------------------------------
+Custom CPU Frequency
+--------------------
 
-See :ref:`projectconf_board_f_cpu` and :ref:`projectconf_upload_speed` options
-from :ref:`projectconf`
+See :ref:`projectconf_board_f_cpu` option from :ref:`projectconf`
 
 .. code-block:: ini
 
     [env:myenv]
-    # set frequency to 40MHz
-    board_f_cpu = 40000000L
+    # set frequency to 160MHz
+    board_f_cpu = 160000000L
 
-    upload_speed = 9600
+Custom FLASH Frequency
+----------------------
+
+See :ref:`projectconf_board_f_flash` option from :ref:`projectconf`. Possible
+values:
+
+* 20000000L
+* 26000000L
+* 40000000L
+* 80000000L
+
+.. code-block:: ini
+
+    [env:myenv]
+    # set frequency to 80MHz
+    board_f_flash = 80000000L
 
 Custom Reset Method
 -------------------
@@ -30,10 +44,7 @@ See :ref:`projectconf_upload_resetmethod` option from :ref:`projectconf`
 
 .. code-block:: ini
 
-    [env:esp12e]
-    platform = espressif
-    framework = arduino
-    board = esp12e
+    [env:myenv]
     upload_resetmethod = ck
 
 .. _platform_espressif_customflash:
@@ -66,6 +77,16 @@ To override default LD script please use :ref:`projectconf_build_flags` from
     [env:myenv]
     build_flags = -Wl,-Tesp8266.flash.4m.ld
 
+Custom Upload Speed
+-------------------
+
+See :ref:`projectconf_upload_speed` option from :ref:`projectconf`
+
+.. code-block:: ini
+
+    [env:myenv]
+    upload_speed = 9600
+
 .. _platform_espressif_uploadfs:
 
 Uploading files to file system SPIFFS

docs/projectconf.rst

@@ -208,6 +208,17 @@ The full list of ``board_f_cpu`` for the popular embedded platforms you can
 find in *Boards* section of :ref:`platforms`. See "Frequency" column. You can
 overclock a board by specifying a ``board_f_cpu`` value other than the default.
 
+.. _projectconf_board_f_flash:
+
+``board_f_flash``
+^^^^^^^^^^^^^^^^^
+
+An option ``board_f_flash`` is used to define FLASH chip frequency (Hertz, Clock). A
+format of this option is ``C-like long integer`` value with ``L`` suffix. The
+1 Hertz is equal to ``1L``, then 40 Mhz (Mega Hertz) is equal to ``40000000L``.
+
+This option isn't available for the all development platforms. The only
+:ref:`platform_espressif` supports it.
 
 Building options
 ~~~~~~~~~~~~~~~~