penguin86/pato-z80-home-computer
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

WIP reimplementing serial terminal with DATA_AVAILABLE register

Browse Source
This commit is contained in:
Daniele Verducci (ZenPenguin)
2020-12-16 08:49:28 +01:00
parent f1e7622e17
commit 2c9675b8f0
3 changed files with 54 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files

29
arduino/arduino_terminal/arduino_terminal.ino
View File

@ -2,19 +2,28 @@
* Terminal interface.
* This sketch allow an Arduino to be used as a terminal to log into Pat80.
* The Arduino is connected to the Pat80 I/O bus and to the terminal computer via USB.
* The Arduino IDE serial monitor is used to send and receive commands to the Z80.
* The Python Terminal Monitor or the Arduino IDE serial monitor is used to send
* and receive commands to/from the Z80.
*
* Seen from the Pat80, the terminal interface has two registers:
* DATA Register at addr 0x00 (\RS) contains the last received byte from the pc
* DATA_AVAILABLE Register at addr 0x01 (RS) contains the number of bytes in the buffer,
* waiting to be read from the Pat80. A READ operation on DATA register removes the
* byte from the buffer and decrements DATA_AVAILABLE.
*/
// EN 2 // Input, Active low
// WR 11 // Input, Active low
// RS 12 // Input, low = DATA register, high = DATA_AVAILABLE register
// DATA BUS (Input/Output, active high): 3, 4, 5, 6, 7, 8, 9, 10;
byte incomingBuffer = 0; // Incoming from computer, to the Pat80
byte outgoingBuffer = 0; // Outgoing to computer, from the Pat80
byte availableBytes = 0; // Available bytes in the incoming buffer (for the DATA_AVAILABLE register)
void setup() {
DDRD = B00000010; // Port D (used arduino pins 2 (EN) and 3 to 7 (DATA)) is input. Avoid changing serial pins.
DDRB = B00000000; // Port B (used arduino pins 8 to 10 (DATA) and 11 (WR)) is input
DDRB = B00000000; // Port B (used arduino pins 8 to 10 (DATA), 11 (WR) and 12 (RS) is input
Serial.begin(2000000);
Serial.println("Pat80 terminal");
@ -25,6 +34,7 @@ void setup() {
void loop() {
if (Serial.available() > 0) {
incomingBuffer = Serial.read();
availableBytes = 1; // TODO: Implement a 256 byte buffer and store the avail bytes number in this var
}
if (outgoingBuffer != 0) {
if ((outgoingBuffer >= 8 && outgoingBuffer <= 13) || (outgoingBuffer >= 32 && outgoingBuffer <= 127)) {
@ -49,10 +59,17 @@ void onClk() {
if ((PINB & B00001000) == B00001000) { // WR is HIGH (Pat80 wants to Read (we send data))
DDRD = DDRD | B11111000; // Port D (arduino pins 3 to 7) is output. In or to preserve serial pins and interrupt pin
DDRB = B00000111; // Port B (0,1,2) = pins 8,9,10 output
// Split byte to two parts
PORTD = incomingBuffer << 3;
PORTB = incomingBuffer >> 5;
incomingBuffer = 0;
if ((PINB & B00010000) == B00010000) { // RS is HIGH: we send number of bytes available in buffer
// Split byte to two parts
PORTD = availableBytes << 3;
PORTB = availableBytes >> 5;
} else {
// Split byte to two parts
PORTD = incomingBuffer << 3;
PORTB = incomingBuffer >> 5;
incomingBuffer = 0;
availableBytes = 0;
}
} else {
// Pat80 wants to Write (we receive data)
outgoingBuffer = (PIND >> 3) | (PINB << 5); // Compose the final byte from the two parts