178 lines
3.4 KiB
C++
178 lines
3.4 KiB
C++
#include <SPI.h>
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#include <MCP23S17.h>
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#define DEBUG 0
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#define KBD_INTERRUPT_ENABLE true
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#define KBD_SEND_TIMEOUT 23
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#define IO_SS 10
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#define IO_VIDEO 0
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#define IO_VIDEO_D0 0
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#define IO_VIDEO_D6 6
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#define VIDEO_RDA 5
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#define VIDEO_DA 3
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#define IO_KBD 1
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#define IO_KBD_D0 8
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#define IO_KBD_D6 14
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#define IO_KBD_DA 15
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#define KBD_READY 2
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#define KBD_STROBE 4
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MCP23S17 bridge(&SPI, IO_SS, 0);
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void setup() {
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Serial.begin(115200);
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configure_pins();
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configure_bridge();
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output_status();
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}
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void configure_pins() {
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pinMode(KBD_READY, INPUT);
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pinMode(VIDEO_DA, INPUT);
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pinMode(KBD_STROBE, OUTPUT);
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pinMode(VIDEO_RDA, OUTPUT);
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}
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void configure_bridge() {
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bridge.begin();
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/* Configure video section */
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for (int i = IO_VIDEO_D0; i <= IO_VIDEO_D6; i++) {
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bridge.pinMode(i, INPUT);
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}
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bridge.pinMode(7, INPUT_PULLUP);
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/* Configure keyboard section */
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for (int i = 8; i <= 15; i++) {
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bridge.pinMode(i, OUTPUT);
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}
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}
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void output_status() {
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Serial.println("RC6502 Apple 1 Replica");
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debug_value("Video DA", digitalRead(VIDEO_DA));
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debug_value("Video D0-D6", bridge.readPort(IO_VIDEO) & 127);
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debug_value("Keyboard RDY", digitalRead(KBD_READY));
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}
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void debug_value(String description, byte value) {
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debug_value(description, value, 1);
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}
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void debug_value(String description, byte value, int level) {
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if (DEBUG < level) return;
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Serial.print(description);
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Serial.print(": ");
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print_hex(value);
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}
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void print_hex(byte value) {
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print_hex(value, true);
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}
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void print_hex(byte value, bool newline) {
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if (value <= 0xF) {
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Serial.print("0x0");
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} else {
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Serial.print("0x");
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}
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if (newline) Serial.println(value, HEX);
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else Serial.print(value, HEX);
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}
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void serial_receive() {
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if (Serial.available() > 0) {
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int c = Serial.read();
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debug_value("PIA RX", c, 10);
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pia_send(c);
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}
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}
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void pia_send(int c) {
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/* Make sure STROBE signal is off */
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digitalWrite(KBD_STROBE, LOW);
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c = map_to_ascii(c);
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/* Output the actual keys as long as it's supported */
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if (c < 96) {
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bridge.writePort(IO_KBD, c | 128);
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digitalWrite(KBD_STROBE, HIGH);
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if (KBD_INTERRUPT_ENABLE) {
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byte timeout;
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/* Wait for KBD_READY (CA2) to go HIGH */
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timeout = KBD_SEND_TIMEOUT;
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while(digitalRead(KBD_READY) != HIGH) {
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delay(1);
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if (timeout == 0) break;
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else timeout--;
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}
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digitalWrite(KBD_STROBE, LOW);
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/* Wait for KBD_READY (CA2) to go LOW */
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timeout = KBD_SEND_TIMEOUT;
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while(digitalRead(KBD_READY) != LOW) {
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delay(1);
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if (timeout == 0) break;
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else timeout--;
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}
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} else {
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delay(KBD_SEND_TIMEOUT);
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digitalWrite(KBD_STROBE, LOW);
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}
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}
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}
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char map_to_ascii(int c) {
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/* Convert ESC key */
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if (c == 203) {
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c = 27;
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}
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/* Ctrl A-Z */
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if (c > 576 && c < 603) {
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c -= 576;
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}
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/* Convert lowercase keys to UPPERCASE */
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if (c > 96 && c < 123) {
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c -= 32;
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}
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return c;
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}
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void serial_transmit() {
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digitalWrite(VIDEO_RDA, HIGH);
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if (digitalRead(VIDEO_DA) == HIGH) {
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char c = bridge.readPort(IO_VIDEO) & 127;
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debug_value("PIA TX", c, 10);
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digitalWrite(VIDEO_RDA, LOW);
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delay(12);
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send_ascii(c);
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}
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}
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char send_ascii(char c) {
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if (DEBUG >= 5) Serial.print("[");
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switch (c) {
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case 0x0d: Serial.println(); /* Replace CR with LF */
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default:
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Serial.print(c);
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}
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if (DEBUG >= 5) Serial.print("]");
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}
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void loop() {
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serial_receive();
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serial_transmit();
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}
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