Add pull-up resistor control

README.md

@@ -174,6 +174,15 @@ int readAllInputs();
 >the bit in the byte is set to 1, if the input is open the bit in the byte is set to 0.  256 will be
 >returned if an error has occured(generally due to lack of communciation with controller).
 
+```cpp
+byte setPullUp(byte pullup);
+```
+>This method accepts one byte. Valid byte arguments 0x00 to 0xFC. A call to this method will set or remove the pull-up
+>resistors on the inputs. Setting the bit corresponding to the MCP23008 input pin will internally pull the pin high
+>through a 100Kohm resistor. By default the pull-up resistors are all enabled. Bit 7-0 corresponds to PU7:PU0
+>excluding bits 0 and 1 as they are the relay driver pins.
+>Example: default setting byte is 0XFC, to turn off the pull-up resistor for input 1 the byte value would be
+>0xF8 (remeber that 0 and 1 are for relay control).
 
 ###Public accessible variables
 ```cpp
@@ -188,4 +197,4 @@ License
 ----
 
 GNU
-[sparkIncludeLibrary]:https://docs.particle.io/guide/getting-started/build/photon/
+[sparkIncludeLibrary]:https://docs.particle.io/guide/getting-started/build/photon/

firmware/NCD2Relay.cpp

@@ -449,3 +449,37 @@ int NCD2Relay::readAllInputs(){
     byte shifted = inverted >> 2;
     return shifted;
 }
+
+void NCD2Relay::setPullUp(byte pullup){
+    // twoRelayMask = 0x03;    // becuase this is the two relay board don't touch GPIO 1 and 2
+    if((pullup & twoRelayMask) > 0x00){
+        skippedPullup = 1;
+        return;
+    }
+    byte registerAddress = 0x06;
+    setPullUpRetry:
+    Wire.beginTransmission(address);
+    Wire.write(registerAddress);
+    Wire.write(pullup);
+    byte status = Wire.endTransmission();
+    if(status !=0){
+        if(retrys < 3){
+    #ifdef LOGGING
+            Serial.println("Retry set pull-up");
+    #endif
+            retrys++;
+            goto setPullUpRetry;
+        }else{
+    #ifdef LOGGING
+        Serial.println("Set Pull Up failed");
+    #endif
+            initialized = false;
+            retrys = 0;
+        }
+
+    }else{
+        initialized = true;
+        retrys = 0;
+        readStatus();
+    }
+}

firmware/NCD2Relay.h

@@ -28,6 +28,8 @@ class NCD2Relay{
     int readInputStatus(int input);
     //Read status of all inputs
     int readAllInputs();
+    //Set input pull-up resistors on or off
+    void setPullUp(byte pullup);
 
     //User Accessible Variables
     //Whether or not the controller is ready to accept commands