Apple-1-Mini/code/firmware/SerialIO/SerialIO.ino

247 lines
6.6 KiB
C++

// ---------------------------------------------------------------------------------- //
// Apple 1 Mini firmware for Arduino //
// //
// Version 1.0 //
// By Ruud van Falier //
// //
// Enables serial communication between an Arduino and the Apple 1 PIA. //
// Also implements a blinking cursor and green text using VT100 escape codes //
// (VT100 codes only tested with PuTTY client!) //
// //
// Heavily based on Propeller source code from Briel Computers' Apple 1 replica. //
// ---------------------------------------------------------------------------------- //
// Port definitions (Arduino pins connected to the PIA)
#define PIN_DA A0
#define PIN_RDA A1
#define PIN_PB0 2
#define PIN_PB1 3
#define PIN_PB2 4
#define PIN_PB3 A5
#define PIN_PB4 A4
#define PIN_PB5 A3
#define PIN_PB6 A2
#define PIN_PA0 5
#define PIN_PA1 6
#define PIN_PA2 7
#define PIN_PA3 8
#define PIN_PA4 9
#define PIN_PA5 10
#define PIN_PA6 11
#define PIN_STROBE 12
#define DELAY_VIDEO 1
#define DELAY_ASCII 1
// VT100 codes (used for cursor and text color implementation)
#define VT100_OFF "\033[0m" // Disable formatting
#define VT100_DEFAULT "\033[32m" // Color green
#define VT100_BLINK "\033[5;32m" // Blink color green
#define VT100_BOLD "\033[1;32m" // Bold color green
#define VT100_CLS "\033[2J" // Clear screen
#define VT100_RESET_CURSOR "\033[H" // Position cursor in top left corner
#define VT100_CURSOR_LEFT "\033[1D" // Move cursor one column to the left
#define VT100_ERASE_EOL "\033[K" // Erase from cursor until end of line
#define CURSOR_CHAR "@"
// Global variables
uint8_t video_data = 0;
uint8_t video_data_pins[] = { PIN_PB0, PIN_PB1, PIN_PB2, PIN_PB3, PIN_PB4, PIN_PB5, PIN_PB6 };
uint8_t serial_data;
bool cursor_visible = false;
/*
* Program initialization
*/
void setup()
{
// Setup video data pins (output from the PIA)
pinMode(PIN_RDA, OUTPUT);
pinMode(PIN_DA, INPUT);
pinMode(PIN_PB0, INPUT);
pinMode(PIN_PB1, INPUT);
pinMode(PIN_PB2, INPUT);
pinMode(PIN_PB3, INPUT);
pinMode(PIN_PB4, INPUT);
pinMode(PIN_PB5, INPUT);
pinMode(PIN_PB6, INPUT);
// Setup ASCII data pins (input for the PIA)
pinMode(PIN_STROBE, OUTPUT);
pinMode(PIN_PA0, OUTPUT);
pinMode(PIN_PA1, OUTPUT);
pinMode(PIN_PA2, OUTPUT);
pinMode(PIN_PA3, OUTPUT);
pinMode(PIN_PA4, OUTPUT);
pinMode(PIN_PA5, OUTPUT);
pinMode(PIN_PA6, OUTPUT);
Serial.begin(9600);
display_boot_message();
}
/*
* Program loop
*/
void loop()
{
process_video_data();
process_serial_data();
}
/*
* Displays the Apple 1 Replica firmware boot message and enables the blinking cursor
*/
void display_boot_message()
{
cursor_visible = false;
Serial.print(VT100_CLS);
Serial.print(VT100_RESET_CURSOR);
Serial.print(VT100_OFF);
Serial.print(VT100_DEFAULT);
Serial.println("+------------------------+");
Serial.print("| ");
Serial.print(VT100_OFF);
Serial.print(VT100_BOLD);
Serial.print("APPLE 1 MINI");
Serial.print(VT100_OFF);
Serial.print(VT100_DEFAULT);
Serial.println(" |");
Serial.print(VT100_OFF);
Serial.print(VT100_DEFAULT);
Serial.println("|------------------------|");
Serial.println("| FIRMWARE VERSION 1.0 |");
Serial.println("| RUUD VAN FALIER, 2017 |");
Serial.println("+------------------------+");
Serial.println();
Serial.println("READY...");
Serial.println();
Serial.print(VT100_OFF);
show_cursor();
}
/*
* Retrieves video (character) data from the PIA and sends it to the user over the serial connection.
*/
void process_video_data()
{
// Tell the PIA we are ready to receive data.
digitalWrite(PIN_RDA, HIGH);
delay(DELAY_VIDEO);
while (digitalRead(PIN_DA))
{
// Data is available.
video_data = 0;
// Decode the data bits to a byte.
for (int i = 0; i < 7; i++)
{
if (digitalRead(video_data_pins[i]))
{
video_data |= (1 << i);
}
}
// Send video data over serial connection.
if (video_data == 13)
{
// Carrage return.
hide_cursor();
Serial.println();
}
else if (video_data > 31)
{
// Display-compatible character.
hide_cursor();
Serial.print(VT100_DEFAULT);
Serial.print((char)video_data);
Serial.print(VT100_OFF);
}
// Done receiving this byte.
digitalWrite(PIN_RDA, LOW);
delay(DELAY_VIDEO);
// Tell the PIA we are ready to receive more data.
digitalWrite(PIN_RDA, HIGH);
delay(DELAY_VIDEO);
}
show_cursor();
}
/*
* Processes data received from the serial connection.
* Puts the received data on to the PIA where the CPU will read it from.
*/
void process_serial_data()
{
// Wait for serial data coming in.
while (Serial.available() > 0)
{
serial_data = Serial.read();
if (serial_data == 203)
{
// Translate uppercase ESC to normal ESC.
serial_data = 27;
}
if (serial_data >= 97 && serial_data <= 122)
{
// Translate lowercase characters to uppercase as the Apple 1 only supports uppercase.
serial_data -= 32;
}
if (serial_data < 96)
{
// Encode any Apple 1 compatible character to data bits.
digitalWrite(PIN_PA6, bitRead(serial_data, 6));
digitalWrite(PIN_PA5, bitRead(serial_data, 5));
digitalWrite(PIN_PA4, bitRead(serial_data, 4));
digitalWrite(PIN_PA3, bitRead(serial_data, 3));
digitalWrite(PIN_PA2, bitRead(serial_data, 2));
digitalWrite(PIN_PA1, bitRead(serial_data, 1));
digitalWrite(PIN_PA0, bitRead(serial_data, 0));
// Pulse the STROBE bit so the PIA will process the input.
digitalWrite(PIN_STROBE, HIGH);
delay(DELAY_ASCII);
digitalWrite(PIN_STROBE, LOW);
}
process_video_data();
}
}
/*
* Remove the cursor character from the screen by sending a backspace.
*/
void hide_cursor()
{
if (cursor_visible)
{
Serial.print(VT100_CURSOR_LEFT);
Serial.print(VT100_ERASE_EOL);
cursor_visible = false;
}
}
/*
* Display blinking cursor character.
*/
void show_cursor()
{
if (!cursor_visible)
{
Serial.print(VT100_BLINK);
Serial.print(CURSOR_CHAR);
Serial.print(VT100_OFF);
cursor_visible = true;
}
}