add OUTPUT_OPEN_DRAIN

disabling pulls on pinMode is not needed, since they are cleared 2
lines above.

Author: ficeto

cores/esp8266/Arduino.h

@@ -47,16 +47,17 @@ void yield(void);
 #define PWMRANGE 1023
 
 //GPIO FUNCTIONS
-#define INPUT           0x00
-#define OUTPUT          0x01
-#define INPUT_PULLUP    0x02
-#define INPUT_PULLDOWN  0x04
-#define SPECIAL         0xF8 //defaults to the usable BUSes uart0rx/tx uart1tx and hspi
-#define FUNCTION_0      0x08
-#define FUNCTION_1      0x18
-#define FUNCTION_2      0x28
-#define FUNCTION_3      0x38
-#define FUNCTION_4      0x48
+#define INPUT             0x00
+#define INPUT_PULLUP      0x02
+#define INPUT_PULLDOWN    0x04
+#define OUTPUT            0x01
+#define OUTPUT_OPEN_DRAIN 0x03
+#define SPECIAL           0xF8 //defaults to the usable BUSes uart0rx/tx uart1tx and hspi
+#define FUNCTION_0        0x08
+#define FUNCTION_1        0x18
+#define FUNCTION_2        0x28
+#define FUNCTION_3        0x38
+#define FUNCTION_4        0x48
 
 #define PI 3.1415926535897932384626433832795
 #define HALF_PI 1.5707963267948966192313216916398

cores/esp8266/core_esp8266_wiring_digital.c

@@ -37,21 +37,20 @@ extern void __pinMode(uint8_t pin, uint8_t mode) {
       GPEC = (1 << pin); //Disable
       GPF(pin) = GPFFS((mode >> 4) & 0x07);
       if(pin == 13 && mode == FUNCTION_4) GPF(pin) |= (1 << GPFPU);//enable pullup on RX
-    }  else if(mode == OUTPUT){
+    }  else if(mode == OUTPUT || mode == OUTPUT_OPEN_DRAIN){
       GPF(pin) = GPFFS(GPFFS_GPIO(pin));//Set mode to GPIO
       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){
       GPF(pin) = GPFFS(GPFFS_GPIO(pin));//Set mode to GPIO
-      GPC(pin) = (GPC(pin) & (0xF << GPCI)) | (1 << GPCD); //SOURCE(GPIO) | DRIVER(OPEN_DRAIN) | INT_TYPE(UNCHANGED) | WAKEUP_ENABLE(DISABLED)
       GPEC = (1 << pin); //Disable
-        if(mode == INPUT_PULLUP) {
-            GPF(pin) &= ~(1 << GPFPD); // Disable Pulldown
-            GPF(pin) |= (1 << GPFPU);  // Enable  Pullup
-        } else if(mode == INPUT_PULLDOWN) {
-            GPF(pin) &= ~(1 << GPFPU); // Disable Pullup
-            GPF(pin) |= (1 << GPFPD);  // Enable  Pulldown
-        }
+      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(pin == 16){
     GPF16 = GP16FFS(GPFFS_GPIO(pin));//Set mode to GPIO