diff --git a/cores/esp8266/core_esp8266_sigma_delta.c b/cores/esp8266/core_esp8266_sigma_delta.c
new file mode 100644
index 000000000..04230211e
--- /dev/null
+++ b/cores/esp8266/core_esp8266_sigma_delta.c
@@ -0,0 +1,192 @@
+/*
+/******************************************************************************
+ * MODULEName : set_sigma MODULE
+
+EACH PIN CAN CONNET TO A SIGMA-DELTA , ALL PINS SHEARS THE SAME SIGMA-DELTA SOURCE.
+
+THE TARGET DUTY AND FREQUENCY CAN BE MODIFIED VIA THE REG ADDR GPIO_SIGMA_DELTA
+
+THE TARGET FREQUENCY IS DEFINED AS:
+
+FREQ = 80,000,000/prescale * target /256  HZ,     0<target<128
+FREQ = 80,000,000/prescale * (256-target) /256  HZ,     128<target<256
+target: duty ,0-255
+prescale: clk_div,0-255
+so the target and prescale will both affect the freq.
+
+
+YOU CAN DO THE TEST LIKE THIS:
+1. INIT :  sigma_delta_setup(PERIPHS_IO_MUX_MTDI_U,12,FUNC_GPIO12);
+2. USE 312K:   set_sigma_duty_312KHz(2);
+OR 2. SET VAL:  set_sigma_target(uint8 target) AND  set_sigma_prescale
+
+3. DEINIT AND DISABLE: sigma_delta_close(uint32 GPIO_NUM), eg.sigma_delta_close(2)
+
+*******************************************************************************/
+
+
+
+#include "osapi.h"
+#include "c_types.h"
+#include "ets_sys.h"
+#include "eagle_soc.h"
+#include "gpio.h"
+
+
+#define GPIO_PIN_ADDR(i)                    (GPIO_PIN0_ADDRESS + i*4)
+#define GPIO_SIGMA_DELTA                    0x60000368  //defined in gpio register.xls
+
+#define GPIO_SIGMA_DELTA_SETTING_MASK       (0x00000001ff)
+
+#define GPIO_SIGMA_DELTA_ENABLE             1
+#define GPIO_SIGMA_DELTA_DISABLE            (~GPIO_SIGMA_DELTA_ENABLE)
+#define GPIO_SIGMA_DELTA_MSB                16
+#define GPIO_SIGMA_DELTA_LSB                16
+#define GPIO_SIGMA_DELTA_MASK               (0x00000001<<GPIO_SIGMA_DELTA_LSB)
+#define GPIO_SIGMA_DELTA_GET(x)             (((x) & GPIO_SIGMA_DELTA_MASK) >> GPIO_SIGMA_DELTA_LSB)
+#define GPIO_SIGMA_DELTA_SET(x)             (((x) << GPIO_SIGMA_DELTA_LSB) & GPIO_SIGMA_DELTA_MASK)
+
+
+#define GPIO_SIGMA_DELTA_TARGET_MSB         7
+#define GPIO_SIGMA_DELTA_TARGET_LSB         0
+#define GPIO_SIGMA_DELTA_TARGET_MASK        (0x000000FF<<GPIO_SIGMA_DELTA_TARGET_LSB)
+#define GPIO_SIGMA_DELTA_TARGET_GET(x)      (((x) & GPIO_SIGMA_DELTA_TARGET_MASK) >> GPIO_SIGMA_DELTA_TARGET_LSB)
+#define GPIO_SIGMA_DELTA_TARGET_SET(x)      (((x) << GPIO_SIGMA_DELTA_TARGET_LSB) & GPIO_SIGMA_DELTA_TARGET_MASK)
+
+
+#define GPIO_SIGMA_DELTA_PRESCALE_MSB       15
+#define GPIO_SIGMA_DELTA_PRESCALE_LSB       8
+#define GPIO_SIGMA_DELTA_PRESCALE_MASK      (0x000000FF<<GPIO_SIGMA_DELTA_PRESCALE_LSB)
+#define GPIO_SIGMA_DELTA_PRESCALE_GET(x)    (((x) & GPIO_SIGMA_DELTA_PRESCALE_MASK) >> GPIO_SIGMA_DELTA_PRESCALE_LSB)
+#define GPIO_SIGMA_DELTA_PRESCALE_SET(x)    (((x) << GPIO_SIGMA_DELTA_PRESCALE_LSB) & GPIO_SIGMA_DELTA_PRESCALE_MASK)
+
+
+/******************************************************************************
+ * FunctionName : sigma_delta_setup
+ * Description  : Init Pin Config for Sigma_delta , change pin source to sigma-delta
+ * Parameters   : uint32 GPIO_MUX, GPIO MUX REG ,DEFINED IN EAGLE_SOC.H, e.g.: PERIPHS_IO_MUX_MTCK_U
+        uint32 GPIO_NUM, GPIO NUM ACCORDING TO THE MUX NUM , e.g.: 13 for MTCK
+        uint32 GPIO_FUNC, GPIO PIN FUNC , DEFINED IN EAGLE_SOC.H , e.g.: FUNC_GPIO13
+ * Returns      : none
+*******************************************************************************/
+void ICACHE_FLASH_ATTR
+sigma_delta_setup(uint32 GPIO_MUX,uint32 GPIO_NUM,uint32 GPIO_FUNC)
+{
+    //============================================================================
+    //STEP 1: SIGMA-DELTA CONFIG;REG SETUP
+    GPIO_REG_WRITE(GPIO_SIGMA_DELTA, 
+                                                        (GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_SIGMA_DELTA_NUM))) &(~GPIO_SIGMA_DELTA_SETTING_MASK))| 
+                                                          GPIO_SIGMA_DELTA_SET(GPIO_SIGMA_DELTA_ENABLE)|
+                                                          GPIO_SIGMA_DELTA_TARGET_SET(0x00)|
+                                                          GPIO_SIGMA_DELTA_PRESCALE_SET(0x00) ); 
+
+    //============================================================================
+
+    //STEP 2: PIN FUNC CONFIG :SET PIN TO GPIO MODE AND ENABLE OUTPUT
+    PIN_FUNC_SELECT(GPIO_MUX, GPIO_FUNC);
+    gpio_output_set(0,0,0x1<<GPIO_NUM,0);
+    
+    //============================================================================
+
+    //STEP 3: CONNECT SIGNAL TO GPIO PAD
+    GPIO_REG_WRITE(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_NUM)),       
+                                                            GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_NUM)))|
+                                                            GPIO_PIN_SOURCE_SET(  SIGMA_AS_PIN_SOURCE )                     );                                                                                    
+    //============================================================================
+    //ets_printf("test reg gpio mtdi : 0x%08x \n",GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_NUM))));
+
+}
+
+
+
+
+/******************************************************************************
+ * FunctionName : sigma_delta_close
+ * Description  : DEinit Pin ,from Sigma_delta mode to GPIO input mode
+ * Parameters   : uint32 GPIO_NUM, GPIO NUM ACCORDING TO THE MUX NUM , e.g.: 13 for MTCK
+ * Returns      : none
+*******************************************************************************/
+void ICACHE_FLASH_ATTR
+    sigma_delta_close(uint32 GPIO_NUM)
+{
+
+    //============================================================================
+    //STEP 1: SIGMA-DELTA DEINIT
+    GPIO_REG_WRITE(GPIO_SIGMA_DELTA, 
+                                                        (GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_SIGMA_DELTA_NUM))) &(~GPIO_SIGMA_DELTA_SETTING_MASK))| 
+                                                          GPIO_SIGMA_DELTA_SET(GPIO_SIGMA_DELTA_DISABLE)|
+                                                          GPIO_SIGMA_DELTA_TARGET_SET(0x00)|
+                                                          GPIO_SIGMA_DELTA_PRESCALE_SET(0x00) ); 
+
+    //ets_printf("test reg gpio sigma : 0x%08x \n",GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_SIGMA_DELTA_NUM))));
+    //============================================================================
+
+    //STEP 2: GPIO OUTPUT DISABLE
+    gpio_output_set(0,0,0,0x1<<GPIO_NUM);
+    //============================================================================
+
+    //STEP 3: CONNECT GPIO TO PIN PAD
+    GPIO_REG_WRITE(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_NUM)),       
+                                                            GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_NUM)))|
+                                                            GPIO_PIN_SOURCE_SET(  GPIO_AS_PIN_SOURCE )                     );                                                                                    
+    //============================================================================
+
+}
+
+
+
+/******************************************************************************
+ * FunctionName : set_sigma_target
+ * Description  : SET TARGET DUTY FOR SIGMA-DELTA 
+ * Parameters   : uint8 target, DUTY NUM , 1BYTE , DUTY RANGE : 0-255
+ * Returns      : none
+*******************************************************************************/
+void ICACHE_FLASH_ATTR
+    set_sigma_target(uint8 target)
+{
+    //set sigma signal duty target
+        GPIO_REG_WRITE(GPIO_SIGMA_DELTA, 
+                                                        (GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_SIGMA_DELTA_NUM))) &(~GPIO_SIGMA_DELTA_TARGET_MASK))| 
+                                                          GPIO_SIGMA_DELTA_TARGET_SET(target)); 
+}
+
+
+
+/******************************************************************************
+ * FunctionName : set_sigma_prescale
+ * Description  : SET SIGMA-DELTA SIGNAL CLK PRESCALE(CLE_DIV)
+ * Parameters   : uint8 prescale, CLK_DIV , 0-255
+ * Returns      : none
+*******************************************************************************/
+void ICACHE_FLASH_ATTR
+    set_sigma_prescale(uint8 prescale)
+{
+    //set sigma signal clk prescale(clk div) 
+        GPIO_REG_WRITE(GPIO_SIGMA_DELTA, 
+                                                        (GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_SIGMA_DELTA_NUM))) &(~GPIO_SIGMA_DELTA_PRESCALE_MASK))| 
+                                                          GPIO_SIGMA_DELTA_PRESCALE_SET(prescale) ); 
+
+}
+
+
+
+/******************************************************************************
+ * FunctionName : set_sigma_duty_312KHz
+ * Description  : 312K CONFIG EXAMPLE
+ * Parameters   : uint8 duty, TARGET DUTY FOR 312K,  0-255
+ * Returns      : none
+*******************************************************************************/
+void ICACHE_FLASH_ATTR
+    set_sigma_duty_312KHz(uint8 duty)
+{
+    
+    uint8 target = 0,prescale=0;
+    target = (duty>128)?(256-duty):duty;
+    prescale = (target==0)?0:(target-1);
+
+    //freq = 80000 (khz) /256 /duty_target * (prescale+1)
+    set_sigma_target(duty);//SET DUTY TARGET
+    set_sigma_prescale(prescale);//SET CLK DIV
+    
+}
+
diff --git a/cores/esp8266/sigma_delta.h b/cores/esp8266/sigma_delta.h
new file mode 100644
index 000000000..c377c0368
--- /dev/null
+++ b/cores/esp8266/sigma_delta.h
@@ -0,0 +1,11 @@
+#ifndef SIGMA_DELTA_H
+#define SIGMA_DELTA_H
+
+#include <stdint.h>
+
+void sigma_delta_close(uint32_t gpio);
+void set_sigma_target(uint8_t target);
+void set_sigma_prescale(uint8_t prescale);
+void set_sigma_duty_312KHz(uint8_t duty);
+
+#endif//SIGMA_DELTA_H