Pulldown only possible for in 16. ( see #478 )

rename define to INPUT_PULLDOWN_16 to make it clear

Author: Links2004

cores/esp8266/Arduino.h

@@ -48,7 +48,7 @@ void yield(void);
 //GPIO FUNCTIONS
 #define INPUT             0x00
 #define INPUT_PULLUP      0x02
-#define INPUT_PULLDOWN    0x04
+#define INPUT_PULLDOWN_16 0x04 // PULLDOWN only possible for pin16
 #define OUTPUT            0x01
 #define OUTPUT_OPEN_DRAIN 0x03
 #define WAKEUP_PULLUP     0x05

cores/esp8266/core_esp8266_wiring_digital.c

@@ -44,14 +44,12 @@ extern void __pinMode(uint8_t pin, uint8_t mode) {
       GPC(pin) = (GPC(pin) & (0xF << GPCI)); //SOURCE(GPIO) | DRIVER(NORMAL) | INT_TYPE(UNCHANGED) | WAKEUP_ENABLE(DISABLED)
       if(mode == OUTPUT_OPEN_DRAIN) GPC(pin) |= (1 << GPCD);
       GPES = (1 << pin); //Enable
-    } else if(mode == INPUT || mode == INPUT_PULLUP || mode == INPUT_PULLDOWN){
+    } else if(mode == INPUT || mode == INPUT_PULLUP){
       GPF(pin) = GPFFS(GPFFS_GPIO(pin));//Set mode to GPIO
       GPEC = (1 << pin); //Disable
       GPC(pin) = (GPC(pin) & (0xF << GPCI)) | (1 << GPCD); //SOURCE(GPIO) | DRIVER(OPEN_DRAIN) | INT_TYPE(UNCHANGED) | WAKEUP_ENABLE(DISABLED)
       if(mode == INPUT_PULLUP) {
           GPF(pin) |= (1 << GPFPU);  // Enable  Pullup
-      } else if(mode == INPUT_PULLDOWN) {
-          GPF(pin) |= (1 << GPFPD);  // Enable  Pulldown
       }
     } else if(mode == WAKEUP_PULLUP || mode == WAKEUP_PULLDOWN){
       GPF(pin) = GPFFS(GPFFS_GPIO(pin));//Set mode to GPIO
@@ -67,8 +65,8 @@ extern void __pinMode(uint8_t pin, uint8_t mode) {
   } else if(pin == 16){
     GPF16 = GP16FFS(GPFFS_GPIO(pin));//Set mode to GPIO
     GPC16 = 0;
-    if(mode == INPUT || mode == INPUT_PULLDOWN){
-      if(mode == INPUT_PULLDOWN){
+    if(mode == INPUT || mode == INPUT_PULLDOWN_16){
+      if(mode == INPUT_PULLDOWN_16){
         GPF16 |= (1 << GP16FPD);//Enable Pulldown
       }
       GP16E &= ~1;