diff --git a/ports/stm8/README-SDCC b/ports/stm8/README-SDCC
new file mode 100644
index 0000000..e69de29
diff --git a/ports/stm8/atomport-asm-sdcc.s b/ports/stm8/atomport-asm-sdcc.s
new file mode 100644
index 0000000..e69de29
diff --git a/ports/stm8/atomport-private.h b/ports/stm8/atomport-private.h
index 3b3d4c0..34e7aa1 100644
--- a/ports/stm8/atomport-private.h
+++ b/ports/stm8/atomport-private.h
@@ -64,13 +64,18 @@
 #define INTERRUPT @far @interrupt @svlreg
 #elif defined (__IAR_SYSTEMS_ICC__)
 #define INTERRUPT __interrupt
-#elif defined(__RCSTM8__)
+#elif defined(__RCSTM8__) || defined(__SDCC_stm8)
 #define INTERRUPT
 #endif
 
 
 /* Function prototypes */
 void archInitSystemTickTimer (void);
+#ifndef __SDCC_stm8
 INTERRUPT void TIM1_SystemTickISR (void);
+#else
+void TIM1_SystemTickISR (void) __interrupt(11);
+#endif
 
 #endif /* __ATOM_PORT_PRIVATE_H */
+
diff --git a/ports/stm8/atomport.c b/ports/stm8/atomport.c
index 5d7df1b..6f9c79f 100644
--- a/ports/stm8/atomport.c
+++ b/ports/stm8/atomport.c
@@ -293,6 +293,8 @@ void archInitSystemTickTimer ( void )
 INTERRUPT void TIM1_SystemTickISR (void)
 #if defined(__RCSTM8__)
 interrupt 11
+#elif defined(__SDCC_stm8)
+__interrupt(11)
 #endif
 {
     /* Call the interrupt entry routine */
diff --git a/ports/stm8/atomport.h b/ports/stm8/atomport.h
index 2063bfb..0371e38 100644
--- a/ports/stm8/atomport.h
+++ b/ports/stm8/atomport.h
@@ -84,6 +84,14 @@
 #define CRITICAL_STORE      unsigned char ccr
 #define CRITICAL_START()    ccr = _getCC_(); _sim_()
 #define CRITICAL_END()      _setCC_(ccr)
+
+/* SDCC: Use custom function */
+#elif defined(__SDCC_stm8)
+uint8_t get_cc(void);
+void set_cc(uint8_t);
+#define CRITICAL_STORE      uint8_t ccr
+#define CRITICAL_START()    ccr = get_cc(); __asm__("sim")
+#define CRITICAL_END()      set_cc(ccr)
 #endif
 
 /* Uncomment to enable stack-checking */
diff --git a/ports/stm8/sdcc.mak b/ports/stm8/sdcc.mak
new file mode 100644
index 0000000..972e879
--- /dev/null
+++ b/ports/stm8/sdcc.mak
@@ -0,0 +1,107 @@
+KERNEL_DIR=../../kernel
+TESTS_DIR=../../tests
+PERIPHS_DIR=stm8s-periphs
+
+CC=sdcc
+ASM=sdasstm8
+LINK=sdcc
+
+# CPU part number
+PART=STM8S105
+
+# Enable stack-checking
+STACK_CHECK=true
+
+# Directory for built objects
+BUILD_DIR=build-sdcc
+
+# Port/application object files
+APP_OBJECTS = atomport.rel tests-main.rel uart.rel
+APP_ASM_OBJECTS = atomport-asm-sdcc.rel
+
+# STM8S Peripheral driver object files
+PERIPH_OBJECTS = stm8s_gpio.rel stm8s_tim1.rel stm8s_clk.rel stm8s_uart2.rel
+
+# Kernel object files
+KERNEL_OBJECTS = atomkernel.rel atomsem.rel atommutex.rel atomtimer.rel atomqueue.rel
+
+# Collection of built objects (excluding test applications)
+ALL_OBJECTS = $(APP_OBJECTS) $(APP_ASM_OBJECTS) $(PERIPH_OBJECTS) $(KERNEL_OBJECTS)
+BUILT_OBJECTS = $(patsubst %,$(BUILD_DIR)/%,$(ALL_OBJECTS))
+
+# Test object files (dealt with separately as only one per application build)
+TEST_OBJECTS = $(notdir $(patsubst %.c,%.rel,$(wildcard $(TESTS_DIR)/*.c)))
+
+# Target application filenames (.elf) for each test object
+TEST_HEXS = $(patsubst %.rel,%.ihx,$(TEST_OBJECTS))
+TEST_ELFS = $(patsubst %.rel,%.elf,$(TEST_OBJECTS))
+
+# Search build/output directory for dependencies
+vpath %.rel .\$(BUILD_DIR)
+vpath %.elf .\$(BUILD_DIR)
+vpath %.hex .\$(BUILD_DIR)
+
+# Compiler/Assembler flags
+CFLAGS= -mstm8 -c -D $(PART) --opt-code-size --max-allocs-per-node 300
+DBG_CFLAGS= -mstm8 -c -D $(PART) --opt-code-size --max-allocs-per-node 3000
+ASMFLAGS= -off
+DBG_ASMFLAGS= -off
+LINKFLAGS= -mstm8
+DBG_LINKFLAGS= -mstm8
+
+# Enable stack-checking (disable if not required)
+ifeq ($(STACK_CHECK),true)
+CFLAGS += -D ATOM_STACK_CHECKING
+DBG_CFLAGS += -D ATOM_STACK_CHECKING
+endif
+
+#################
+# Build targets #
+#################
+
+# All tests
+all: $(BUILD_DIR) $(TEST_HEXS) sdcc.mak
+
+# Make build/output directory
+$(BUILD_DIR):
+	mkdir $(BUILD_DIR)
+
+# Test HEX files (one application build for each test)
+$(TEST_HEXS): %.ihx: %.rel $(KERNEL_OBJECTS) $(PERIPH_OBJECTS) $(APP_OBJECTS) $(APP_ASM_OBJECTS)
+	$(LINK) $(BUILD_DIR)/$(notdir $<) $(BUILT_OBJECTS) $(LINKFLAGS) -o $(BUILD_DIR)/$@
+
+# Test ELF files (one application build for each test)
+$(TEST_ELFS): %.elf: %.rel $(KERNEL_OBJECTS) $(PERIPH_OBJECTS) $(APP_OBJECTS) $(APP_ASM_OBJECTS)
+	$(LINK) $(BUILD_DIR)/$(notdir $<) $(BUILT_OBJECTS) $(LINKFLAGS) --out-fmt-elf -o $(BUILD_DIR)/$@
+
+# Kernel objects builder
+$(KERNEL_OBJECTS): %.rel: $(KERNEL_DIR)/%.c
+	$(CC) $< $(CFLAGS) -I . -I $(PERIPHS_DIR) -o $(BUILD_DIR)/$*.rel
+
+# Test objects builder
+$(TEST_OBJECTS): %.rel: $(TESTS_DIR)/%.c
+	$(CC) $< $(CFLAGS) -I . -I $(KERNEL_DIR) -I $(PERIPHS_DIR) -o $(BUILD_DIR)/$*.rel
+
+# Peripheral objects builder
+$(PERIPH_OBJECTS): %.rel: $(PERIPHS_DIR)/%.c
+	$(CC) $< $(CFLAGS) -I . -I $(PERIPHS_DIR) -o $(BUILD_DIR)/$*.rel
+
+# Application C objects builder
+$(APP_OBJECTS): %.rel: ./%.c
+	$(CC) $< $(CFLAGS) -I . -I $(KERNEL_DIR) -I $(TESTS_DIR) -I $(PERIPHS_DIR) -o $(BUILD_DIR)/$*.rel
+
+# Application asm objects builder
+$(APP_ASM_OBJECTS): %.rel: ./%.s
+	$(ASM) $(ASMFLAGS) $(BUILD_DIR)/$(notdir $@) $<
+
+# Clean
+clean:
+	rm -f *.o *.elf *.map *.hex *.bin *.lst *.stm8 *.s19
+	rm -rf doxygen-kernel
+	rm -rf doxygen-stm8
+	rm -rf build-sdcc
+
+doxygen:
+	doxygen $(KERNEL_DIR)/Doxyfile
+	doxygen ./Doxyfile
+
diff --git a/ports/stm8/stm8s-periphs/stm8s.h b/ports/stm8/stm8s-periphs/stm8s.h
index 8642bf9..d2190bd 100644
--- a/ports/stm8/stm8s-periphs/stm8s.h
+++ b/ports/stm8/stm8s-periphs/stm8s.h
@@ -30,15 +30,23 @@
 #if defined(__CSMC__)
  #undef _RAISONANCE_
  #undef _IAR_SYSTEMS_
+ #undef _SDCC_
  #define _COSMIC_
 #elif defined(__RCST7__)
  #undef _COSMIC_
  #undef _IAR_SYSTEMS_
+ #undef _SDCC_
  #define _RAISONANCE_
 #elif defined(__IAR_SYSTEMS_ICC__)
  #undef _COSMIC_
  #undef _RAISONANCE_
+ #undef _SDCC_
  #define _IAR_SYSTEMS_
+#elif defined(__SDCC_stm8)
+ #undef _COSMIC_
+ #undef _RAISONANCE_
+ #undef _IAR_SYSTEMS_
+ #define _SDCC_
 #else
  #error "Unsupported Compiler!"          /* Compiler defines not found */
 #endif
@@ -90,6 +98,11 @@
  #define __CONST  const
 #endif
 
+#ifdef _SDCC_
+ #define NEAR
+ #define __CONST  const
+#endif
+
 #ifdef PointerAttr_Far
  #define PointerAttr FAR 
 #else /* PointerAttr_Near */