diff --git a/cores/esp8266/core_esp8266_sigma_delta.c.unused b/cores/esp8266/core_esp8266_sigma_delta.c.unused
deleted file mode 100644
index 04230211e..000000000
--- a/cores/esp8266/core_esp8266_sigma_delta.c.unused
+++ /dev/null
@@ -1,192 +0,0 @@
-/*
-/******************************************************************************
- * 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/core_esp8266_waveform.c b/cores/esp8266/core_esp8266_waveform.c
index 360730bbd..d4d5f5a71 100644
--- a/cores/esp8266/core_esp8266_waveform.c
+++ b/cores/esp8266/core_esp8266_waveform.c
@@ -102,13 +102,6 @@ static inline ICACHE_RAM_ATTR uint32_t min_u32(uint32_t a, uint32_t b) {
   return b;
 }
 
-static inline ICACHE_RAM_ATTR uint32_t min_s32(int32_t a, int32_t b) {
-  if (a < b) {
-    return a;
-  }
-  return b;
-}
-
 static inline ICACHE_RAM_ATTR void ReloadTimer(uint32_t a) {
   // Below a threshold you actually miss the edge IRQ, so ensure enough time
   if (a > 32) {
@@ -251,7 +244,8 @@ static ICACHE_RAM_ATTR void timer1Interrupt() {
 
       // Check for toggles
       now = GetCycleCount();
-      if (now >= wave->nextServiceCycle) {
+      int32_t cyclesToGo = wave->nextServiceCycle - now;
+      if (cyclesToGo < 0) {
         wave->state = !wave->state;
         if (wave->state) {
           SetGPIO(wave->gpioMask);