Non-functional version of serial communications

RC6502 Serial IO/RC6502 Serial IO.sch

@@ -217,7 +217,7 @@ NoConn ~ 3900 4150
 Text GLabel 2650 2850 0    60   Input ~ 0
 VCC
 Text GLabel 3950 950  2    60   Input ~ 0
-KBD_DA
+KBD_STROBE
 Text GLabel 3950 1050 2    60   Output ~ 0
 KBD_READY
 NoConn ~ 3950 1150
@@ -302,8 +302,6 @@ F 3 "" H 5950 2800 50  0001 C CNN
 	1    5700 1800
 	1    0    0    -1  
 $EndComp
-Text GLabel 2650 1750 0    60   Output ~ 0
-KBD_D7
 Text GLabel 5200 1900 0    60   Input ~ 0
 OUT_D0
 Text GLabel 5200 2000 0    60   Input ~ 0
@@ -463,12 +461,10 @@ Wire Wire Line
 	8350 1450 8350 1300
 Wire Wire Line
 	8350 1300 8100 1300
-Text GLabel 5200 2600 0    60   Output ~ 0
-OUT_D7
 Text GLabel 7400 1400 0    60   Input ~ 0
 KBD_READY
 Text GLabel 7400 1600 0    60   Output ~ 0
-KBD_DA
+KBD_STROBE
 Text GLabel 7400 1700 0    60   Output ~ 0
 OUT_READY
 Text GLabel 7400 1500 0    60   Input ~ 0
@@ -617,4 +613,11 @@ NoConn ~ 7400 1200
 NoConn ~ 7400 1100
 NoConn ~ 7400 1000
 NoConn ~ 7400 1300
+NoConn ~ 5200 2600
+Text GLabel 2025 1600 1    60   Input ~ 0
+VCC
+Wire Wire Line
+	2025 1600 2025 1750
+Wire Wire Line
+	2025 1750 2650 1750
 $EndSCHEMATC

RC6502 Serial IO/pia_bridge/pia_bridge.ino

@@ -0,0 +1,117 @@
+#include <SPI.h>
+#include <MCP23S17.h>
+
+#define IO_SS 10
+#define IO_KBD_D0 8
+#define IO_KBD_D6 14
+#define IO_KBD_DA 15
+
+#define IO_VIDEO_D0 0
+#define IO_VIDEO_D6 6
+#define IO_VIDEO_DA 7
+
+#define KBD_READY 2
+#define KBD_STROBE 4
+
+#define VIDEO_RDA 5
+#define VIDEO_DA 3
+
+MCP23S17 bridge(&SPI, IO_SS, 0);
+
+void setup() {
+  Serial.begin(115200);
+  Serial.println("Initializing...");
+  configure_pins();
+  configure_bridge();
+  Serial.println("Initialization done!");
+}
+
+void configure_pins() {
+  pinMode(KBD_READY, INPUT);
+  pinMode(VIDEO_DA, INPUT);
+  pinMode(KBD_STROBE, OUTPUT);
+  pinMode(VIDEO_RDA, OUTPUT);
+}
+
+void configure_bridge() {
+  bridge.begin();
+
+  /* Configure video section */
+  for (int i = 0; i <= 6; i++) {
+    bridge.pinMode(i, INPUT);
+  }
+  bridge.pinMode(7, OUTPUT);
+
+  /* Configure keyboard section */
+  for (int i = 8; i <= 15; i++) {
+    bridge.pinMode(i, OUTPUT);
+  }
+}
+
+byte incomingByte;
+void handle_input() {
+  if (Serial.available() > 0) {
+    digitalWrite(KBD_STROBE, LOW);
+    incomingByte = Serial.read();
+
+    /* Convert ESC key */
+    if (incomingByte == 203) {
+      incomingByte = 27;
+    }
+
+    /* Convert lowercase keys to UPPERCASE */
+    if (incomingByte > 96 && incomingByte < 123) {
+      incomingByte -= 32;
+    }
+
+    if (incomingByte == 65) {
+      incomingByte = 10;
+    }
+    if (incomingByte == 66) {
+      incomingByte = 13;
+    }
+
+    /* Output the actual keys as long as it's supported */
+    if (incomingByte < 96) {
+      bridge.writePort(1, reverse(incomingByte));
+      digitalWrite(KBD_STROBE, HIGH);
+      delay(20);
+      digitalWrite(KBD_STROBE, LOW);
+      //Serial.print("TX ");
+      //print_chr(incomingByte);
+    }
+  }
+}
+
+unsigned char reverse( unsigned char x ) 
+{ 
+   x = ((x >> 1) & 0x55) | ((x << 1) & 0xaa); 
+   x = ((x >> 2) & 0x33) | ((x << 2) & 0xcc); 
+   x = ((x >> 4) & 0x0f) | ((x << 4) & 0xf0); 
+   return x;    
+}
+
+void handle_output() {
+  digitalWrite(VIDEO_RDA, HIGH);
+
+  if (digitalRead(VIDEO_DA) == HIGH) {
+    char incomingByte = bridge.readPort(0) & 127;
+    digitalWrite(VIDEO_RDA, LOW);
+    delay(12);
+
+    Serial.print("RX ");
+    print_chr(incomingByte);
+  }
+}
+
+void print_chr(char c) {
+    Serial.print((char) c);
+    Serial.print(" (0x");
+    Serial.print(c, HEX);
+    Serial.println(")");
+}
+
+void loop() {
+  handle_input();
+  handle_output();
+}