60 lines
2.0 KiB
C++
60 lines
2.0 KiB
C++
/**
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* Terminal interface.
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* This sketch allow an Arduino to be used as a terminal to log into Pat80.
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* The Arduino is connected to the Pat80 I/O bus and to the terminal computer via USB.
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* The Arduino IDE serial monitor is used to send and receive commands to the Z80.
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*/
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// EN 2 // Active low
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// WR 11 // Active low
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// DATA BUS IS: 3, 4, 5, 6, 7, 8, 9, 10;
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byte incomingBuffer = 0; // Incoming from computer, to the Pat80
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byte outgoingBuffer = 0; // Outgoing to computer, from the Pat80
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void setup() {
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Serial.begin(2000000);
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Serial.println("Pat80 terminal");
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DDRD = B00000010; // Port D (used arduino pins 2 (EN) and 3 to 7 (DATA)) is input. Avoid changing serial pins.
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DDRB = B00000000; // Port B (used arduino pins 8 to 10 (DATA) and 11 (WR)) is input
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attachInterrupt(digitalPinToInterrupt(2), onClk, CHANGE);
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}
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void loop() {
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if (Serial.available() > 0) {
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incomingBuffer = Serial.read();
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}
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if (outgoingBuffer != 0) {
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if ((outgoingBuffer >= 8 && outgoingBuffer <= 13) || (outgoingBuffer >= 32 && outgoingBuffer <= 127)) {
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// Printable character
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Serial.print((char)outgoingBuffer);
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} else {
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// Non-printable character
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Serial.print("[0x");
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Serial.print(outgoingBuffer, HEX);
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Serial.print("]");
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}
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}
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}
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void onClk() {
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if (PINB & B00000100 == B00000100) { // If EN is HIGH (clock pulse finished)
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// Clock pulse finished, return to high impedance state
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DDRD = B00000010;
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DDRB = B00000000;
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} else {
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// EN is LOW: Clock pulse started
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if (PIND & B00001000 == B00001000) { // WR is HIGH (Pat80 wants to Read (we send data))
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DDRD = DDRD | B11111000; // Port D (arduino pins 3 to 7) is output. In or to preserve serial pins and interrupt pin
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DDRB = B00000111; // Port B (0,1,2) = pins 8,9,10 output
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// Split byte to two parts
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PORTD = incomingBuffer << 3;
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PORTB = incomingBuffer >> 5;
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} else {
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// Pat80 wants to Write (we receive data)
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outgoingBuffer = (PIND >> 3) | (PINB << 5); // Compose the final byte from the two parts
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}
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}
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}
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