rename keybrd_MCP23018.ino to keybrd_MCP23017.ino, works on both MCP23017 and MCP23018

examples/keybrd_MCP23017/keybrd_MCP23017.ino

@@ -1,5 +1,16 @@
 /* keybrd_MCP23017.ino
 
+This sketch:
+    is a simple 1-layer keyboard
+    runs on two matrices of a breadboard keyboard
+    runs on both MCP23017 and MCP23018 IOEs (LED on/off will be reversed on MCP23017)
+
+  Controller                I/O expander
+| Left  | **0** | **1** | | Right | **0** | **1** |
+|-------|-------|-------| |-------|-------|-------|
+| **1** |   1   |   2   | | **1** |   3   |   4   |
+| **0** |   a   |   b   | | **0** |  fn   | z   9 |
+
 MCP23017 pin assignments
 DESTINATION  PIN PIN_NUMBER  PIN   DESTINATION
      row0    GPB0  1     28 GPA7
@@ -17,4 +28,129 @@ DESTINATION  PIN PIN_NUMBER  PIN   DESTINATION
      LC 18   SDA  13     16 A1       GND
               NC  14     15 A0       GND
 
+MCP23018 pin assignments
+DESTINATION  PIN PIN_NUMBER  PIN    DESTINATION
+     GND     VSS   1     28  NC
+             NC    2     27  GPA7
+     row0    GPB0  3     26  GPA6
+     row1    GPB1  4     25  GPA5
+             GPB2  5     24  GPA4
+             GPB4  7     22  GPA2
+             GPB5  8     21  GPA1   col1
+             GPB6  9     20  GPA0   col0
+             GPB7 10     19  INTA
+     LC 3.3V VCC  11     18  INTB
+     LC 19   SCL  12     17  NC
+     LC 18   SDA  13     16  /RESET VCC
+             NC   14     15  ADDR   GND
+
 */
+// ################## GLOBAL ###################
+// ================= INCLUDES ==================
+#include <ScanDelay.h>
+#include <Code_Sc.h>
+#include <Row.h>
+
+#include <Code_LayerHold.h>
+#include <Key_LayeredKeys.h>
+#include <LayerState_LED.h>
+#include <LED_PortOpenDrain.h>
+
+//left matrix
+#include <Scanner_uC.h>
+
+//right matrix
+#include <Port_MCP23018.h>
+#include <Scanner_IOE.h>
+
+// ============ SPEED CONFIGURATION ============
+ScanDelay scanDelay(9000);
+
+/* ================ LEFT SCANNER ===============
+Left matrix rows work the same as the ones in keybrd_2_single-layer.ino
+*/
+uint8_t readPins[] = {14, 15};
+const uint8_t readPinCount = sizeof(readPins)/sizeof(*readPins);
+
+Scanner_uC scanner_L(LOW, readPins, readPinCount);
+
+// =============== RIGHT SCANNER ===============
+const uint8_t IOE_ADDR = 0x20;                  //MCP23018 ADDR pin grounded
+
+Port_MCP23018 portA(IOE_ADDR, 0, 1<<0 | 1<<1 ); //read pins 0, 1
+Port_MCP23018 portB(IOE_ADDR, 1, 0);
+Scanner_IOE scanner_R(LOW, portB, portA);
+
+// ================= RIGHT LED =================
+LED_PortOpenDrain LED_normal(portA, 1<<2);      //LED on/off will be reversed on MCP23017 
+LED_PortOpenDrain LED_fn(portB, 1<<2);          // because it's not open drain
+
+// =================== CODES ===================
+// ---------------- LAYER CODES ----------------
+enum layerIds { NORMAL, FN };
+
+LEDInterface* prtsLayerLEDs[] = { &LED_normal, &LED_fn }; //array index matches enum layerIds
+LayerState_LED layerState(prtsLayerLEDs);
+
+Code_LayerHold l_fn(FN, layerState);
+
+// ---------------- SCAN CODES -----------------
+Code_Sc s_a(KEY_A);
+Code_Sc s_b(KEY_B);
+Code_Sc s_z(KEY_Z);
+
+Code_Sc s_1(KEY_1);
+Code_Sc s_2(KEY_2);
+Code_Sc s_3(KEY_3);
+Code_Sc s_4(KEY_4);
+Code_Sc s_9(KEY_9);
+
+// =================== KEYS ====================
+Key* const ptrsKeys_z9[] = { &s_z, &s_9 };
+Key_LayeredKeys k_z9(ptrsKeys_z9);
+
+LayerStateInterface& Key_LayeredKeys::refLayerState = layerState;
+
+// =================== ROWS ====================
+// ---------------- LEFT ROWS ------------------
+Key* ptrsKeys_L0[] = { &s_1, &s_2 };
+const uint8_t KEY_COUNT_L0 = sizeof(ptrsKeys_L0)/sizeof(*ptrsKeys_L0);
+Row row_L0(scanner_L, 0, ptrsKeys_L0, KEY_COUNT_L0);
+
+Key* ptrsKeys_L1[] = { &s_a, &s_b };
+const uint8_t KEY_COUNT_L1 = sizeof(ptrsKeys_L1)/sizeof(*ptrsKeys_L1);
+Row row_L1(scanner_L, 1, ptrsKeys_L1, KEY_COUNT_L1);
+
+// ---------------- RIGHT ROWS -----------------
+Key* ptrsKeys_R0[] = { &s_3, &s_4 };
+const uint8_t KEY_COUNT_R0 = sizeof(ptrsKeys_R0)/sizeof(*ptrsKeys_R0);
+Row row_R0(scanner_R, 1<<0, ptrsKeys_R0, KEY_COUNT_R0);
+
+Key* ptrsKeys_R1[] = { &l_fn,  &k_z9 };
+const uint8_t KEY_COUNT_R1 = sizeof(ptrsKeys_R1)/sizeof(*ptrsKeys_R1);
+Row row_R1(scanner_R, 1<<1, ptrsKeys_R1, KEY_COUNT_R1);
+
+// ################### MAIN ####################
+void setup()
+{
+    delay(6000);
+    Keyboard.print("keybrd_MCP23017.ino ");
+
+    scanner_R.begin();
+    layerState.begin();
+}
+
+void loop()
+{
+    //left matrix
+    row_L0.process();
+    row_L1.process();
+
+    //right matrix
+    row_R0.process();
+    row_R1.process();
+
+    scanDelay.delay();
+    //debug.printScansPerSecond();
+    //debug.printMicrosecondsPerScan();
+}

examples/keybrd_MCP23018/keybrd_MCP23018.ino

@@ -1,117 +0,0 @@
-/* keybrd_MCP23018.ino
-
-This sketch:
-    is a simple 1-layer keyboard
-    runs on two matrices of a breadboard keyboard
-
-  Controller                I/O expander
-| Left  | **0** | **1** | | Right | **0** | **1** |
-|-------|-------|-------| |-------|-------|-------|
-| **1** |   1   |   2   | | **1** |   3   |   4   |
-| **0** |   a   |   b   | | **0** |   c   |   d   |
-
-MCP23018 pin assignments
-DESTINATION  PIN PIN_NUMBER  PIN    DESTINATION
-     GND     VSS   1     28  NC
-             NC    2     27  GPA7
-     row0    GPB0  3     26  GPA6
-     row1    GPB1  4     25  GPA5
-             GPB2  5     24  GPA4
-             GPB4  7     22  GPA2
-             GPB5  8     21  GPA1   col1
-             GPB6  9     20  GPA0   col0
-             GPB7 10     19  INTA
-     LC 3.3V VCC  11     18  INTB
-     LC 19   SCL  12     17  NC
-     LC 18   SDA  13     16  /RESET VCC
-             NC   14     15  ADDR   GND
-
-*/
-// ################## GLOBAL ###################
-// ================= INCLUDES ==================
-#include <ScanDelay.h>
-#include <Code_Sc.h>
-#include <Row.h>
-
-//left matrix
-#include <Scanner_uC.h>
-
-//right matrix
-#include <Port_MCP23018.h>
-#include <Scanner_IOE.h>
-#include <LED_PortOpenDrain.h>
-
-// ============ SPEED CONFIGURATION ============
-ScanDelay scanDelay(9000);
-
-/* ================ LEFT SCANNER ===============
-Left matrix rows work the same as the ones in keybrd_2_single-layer.ino
-*/
-uint8_t readPins[] = {14, 15};
-const uint8_t readPinCount = sizeof(readPins)/sizeof(*readPins);
-
-Scanner_uC scanner_L(LOW, readPins, readPinCount);
-
-// =============== RIGHT SCANNER ===============
-const uint8_t IOE_ADDR = 0x20;                  //MCP23018 ADDR pin grounded
-
-Port_MCP23018 portA(IOE_ADDR, 0, 1<<0 | 1<<1 ); //read pins 0, 1
-Port_MCP23018 portB(IOE_ADDR, 1, 0);
-Scanner_IOE scanner_R(LOW, portB, portA);
-
-// ================= RIGHT LED =================
-LED_PortOpenDrain LED_capsLck(portA, 1<<7);
-
-// =================== CODES ===================
-Code_Sc s_a(KEY_A);
-Code_Sc s_b(KEY_B);
-Code_Sc s_c(KEY_C);
-Code_Sc s_d(KEY_D);
-
-Code_Sc s_1(KEY_1);
-Code_Sc s_2(KEY_2);
-Code_Sc s_3(KEY_3);
-Code_Sc s_4(KEY_4);
-
-// =================== ROWS ====================
-// ---------------- LEFT ROWS ------------------
-Key* ptrsKeys_L0[] = { &s_1, &s_2 };
-const uint8_t KEY_COUNT_L0 = sizeof(ptrsKeys_L0)/sizeof(*ptrsKeys_L0);
-Row row_L0(scanner_L, 0, ptrsKeys_L0, KEY_COUNT_L0);
-
-Key* ptrsKeys_L1[] = { &s_a, &s_b };
-const uint8_t KEY_COUNT_L1 = sizeof(ptrsKeys_L1)/sizeof(*ptrsKeys_L1);
-Row row_L1(scanner_L, 1, ptrsKeys_L1, KEY_COUNT_L1);
-
-// ---------------- RIGHT ROWS -----------------
-Key* ptrsKeys_R0[] = { &s_3, &s_4 };
-const uint8_t KEY_COUNT_R0 = sizeof(ptrsKeys_R0)/sizeof(*ptrsKeys_R0);
-Row row_R0(scanner_R, 1<<0, ptrsKeys_R0, KEY_COUNT_R0);
-
-Key* ptrsKeys_R1[] = { &s_c,  &s_d };
-const uint8_t KEY_COUNT_R1 = sizeof(ptrsKeys_R1)/sizeof(*ptrsKeys_R1);
-Row row_R1(scanner_R, 1<<1, ptrsKeys_R1, KEY_COUNT_R1);
-
-// ################### MAIN ####################
-void setup()
-{
-    delay(6000);
-    Keyboard.print("keybrd_MCP23018.ino ");
-
-    scanner_R.begin();
-}
-
-void loop()
-{
-    //left matrix
-    row_L0.process();
-    row_L1.process();
-
-    //right matrix
-    row_R0.process();
-    row_R1.process();
-
-    scanDelay.delay();
-    //debug.printScansPerSecond();
-    //debug.printMicrosecondsPerScan();
-}

src/LED_Port.h

@@ -7,8 +7,9 @@
 
 /* An LED_Port object is an I/O expander output pin that is connected to an LED indicator light.
 LED_Port functions turn LED on and off.
+LED anode connected to ouput pin.  LED cathode grounded.
 
-This is for push-pull ouput pins.
+This class is for push-pull ouput pins.
 For LEDs connected to open drain output types, use LED_Port class.
 
 Example initialization:

src/LED_PortOpenDrain.cpp

@@ -3,7 +3,7 @@
 */
 void LED_PortOpenDrain::on()
 {
-    refPort.writeLow(pin);
+    refPort.writeLow(pin);                      //sink output pin
 }
 
 void LED_PortOpenDrain::off()

src/LED_PortOpenDrain.h

@@ -7,8 +7,9 @@
 
 /* An LED_PortOpenDrain object is an I/O expander ouput pin that is connected to an LED.
 LED_PortOpenDrain functions turn LED on and off.
+LED anode connected to power.  LED cathode connected to open-drain ouput pin.
 
-This is for open drain ouput pins.
+This class is for open drain ouput pins.
 For LEDs connected to push-pull output types, use LED_Port class.
 
 Example initialization:

src/Port_MCP23018.h

@@ -9,9 +9,11 @@
 write pins are connected to matrix Row (strobe pin) or LED.
 readPins are connected to matrix column to read which keys are pressed.
 
-MCP23018 has open-drain outputs (open-drain can only sink current).  If LEDs are used, connect:
+Port_MCP23018 can only be active low (Scanner_IOE::activeState = LOW).
-    LED anodes (the longer lead) to power
+Open-drain active high would not work because pull down resistors have no effect on sink.
-    LED cathodes (the shorter lead) to GPIO pin
+ https://en.wikipedia.org/wiki/Open_collector
+
+Use LED_PortOpenDrain class for indicator LEDs.
 
 Instantiation
  ------------

tutorials/keybrd_5b_LED_on_IOE/keybrd_5b_LED_on_IOE.ino

@@ -59,7 +59,7 @@ LED_Port LED_normal(portA, 1<<5);
 LED_Port LED_fn(portB, 1<<4);
 
 // =================== CODES ===================
-// ---------------- LAYER CODE -----------------
+// ---------------- LAYER CODES ----------------
 enum layerIds { NORMAL, FN };
 
 LEDInterface* prtsLayerLEDs[] = { &LED_normal, &LED_fn }; //array index matches enum layerIds
@@ -134,9 +134,8 @@ so that scanner's ports can turn on LayerState_LED's default-layer LED.
 */
 void setup()
 {
-    Keyboard.begin();
     scanner_R.begin();
-    layerState.begin();                 //call LayerState_LED::begin() after Scanner_IOE::begin()
+    layerState.begin();               //todo call LayerState_LED::begin() after Scanner_IOE::begin()
 }
 
 void loop()