Update 2A3A1-AMPCD.ino (#105)

The backlighting didn't work on the AMPCD. The controls would randomly become unresponsive.

Reviewed the prior sample code from TonyG, and updated the code to match it closer. I'm pretty sure that the fix was setting the IRQ pin 6 to an output in the setup loop.

The backlighting was fixed by setting the pinmode to output in the setup.

Closes #104

embedded/OH2_Lower_Instrument_Panel/2A3A1-AMPCD/2A3A1-AMPCD.ino

@@ -54,7 +54,7 @@
  * 10  | HDG -
  * 4   | CRS +
  * 7   | CRS -
- *
+ * 6   | AMPCD IRQ Pin
  * 
  *
  * @brief following #define tells DCS-BIOS that this is a RS-485 slave device.
@@ -91,6 +91,7 @@
 #define UART1_SELECT    ///< Selects UART1 on Arduino for serial communication
 
 #include "DcsBios.h"
+#include "Wire.h"
 #include "TCA9534.h"
 
 // Define pins per the OH Interconnect.
@@ -101,8 +102,7 @@
 #define CRS_P 4              ///< CRS +
 #define CRS_M 7              ///< CRS -
 #define AMPCD_BACK_LIGHT A9  ///< DDI Backlighting PWM
-
-
+#define AMPCD_IRQ 6 ///< AMPCD IRQ Pin
 
 /**
 * TCA9534 Chip Array
@@ -116,15 +116,15 @@ TCA9534 ampcdButtons[4] = {
   TCA9534(0x21)
 };  // Bottom Row
 
-
-
 // Setup global variables for reading DDI button presses.
 bool lastBtnState[28];               ///< Array to hold the last state of the 20 AMPCD buttons, and 4 rocker switches.
 bool buttonState[28];                ///< Array to hold the current state of the 20 AMPCD buttons, and 4 rocker switches.
 uint8_t inputRegister[4];            ///< Input register for button read logic.
 unsigned long lastDebounceTime[28];  ///< Array to hold last time of AMPCD button update for debounce.
 unsigned long debounceDelay = 10;    ///< The debounce delay duration in ms, **increase if the output flickers**.
 
+int index;
+
 /// DCS Bios Messages for the 4 AMPCD rocker switches.
 char *AMPCD_Btns[] = { "AMPCD_GAIN_SW",
                        "AMPCD_NIGHT_DAY",
@@ -159,6 +159,10 @@ void setup() {
   // Run DCS Bios setup function
   DcsBios::setup();
 
+  pinMode(AMPCD_IRQ, OUTPUT);
+
+  pinMode(AMPCD_BACK_LIGHT, OUTPUT); // set backlight pinmode to output
+  analogWrite(AMPCD_BACK_LIGHT, 0); // turn-off backlighting
   /**
 * @brief Initialize last button state array to all 0's.
 *
@@ -206,7 +210,7 @@ void loop() {
 */
     for (int j = 0; j < 7; j++) {
 
-      int index = j + (7 * i);
+      index = j + (7 * i);
 
       bool btnState = (inputRegister[i] >> (6 - j)) & 1;