From 0f02622467e3cdcc4ac2e44d23437c548385756a Mon Sep 17 00:00:00 2001
From: Donna Whisnant <dewhisna@users.noreply.github.com>
Date: Sun, 11 Nov 2018 13:01:52 -0600
Subject: [PATCH] Add support for BOARD_SPEED setting. This is needed to
 specify CPU speed for boards.txt files that use this format:
 "{board_tag}.menu.speed.{board_speed}.build.f_cpu" For example, the Watterott
 ATmega328PB library: https://github.com/watterott/ATmega328PB-Testing

---
 Arduino.mk | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/Arduino.mk b/Arduino.mk
index 0f34a82..5ff186e 100644
--- a/Arduino.mk
+++ b/Arduino.mk
@@ -641,6 +641,11 @@ else
     $(call show_config_variable,BOARD_TAG,[USER])
 endif
 
+ifdef BOARD_SPEED
+    BOARD_SPEED := $(strip $(BOARD_SPEED))
+    $(call show_config_variable,BOARD_SPEED,[USER])
+endif
+
 # If NO_CORE is set, then we don't have to parse boards.txt file
 # But the user might have to define MCU, F_CPU etc
 ifeq ($(strip $(NO_CORE)),)
@@ -686,7 +691,12 @@ ifeq ($(strip $(NO_CORE)),)
     endif
 
     ifndef F_CPU
-        F_CPU := $(call PARSE_BOARD,$(BOARD_TAG),menu.(chip|cpu).$(BOARD_SUB).build.f_cpu)
+        ifdef BOARD_SPEED
+            F_CPU := $(call PARSE_BOARD,$(BOARD_TAG),menu.speed.$(BOARD_SPEED).build.f_cpu)
+        endif
+        ifndef F_CPU
+            F_CPU := $(call PARSE_BOARD,$(BOARD_TAG),menu.(chip|cpu).$(BOARD_SUB).build.f_cpu)
+        endif
         ifndef F_CPU
             F_CPU := $(call PARSE_BOARD,$(BOARD_TAG),build.f_cpu)
         endif