USB_Laptop_Keyboard_Controller/Example_Touchpads/ADB_Trackball.ino
2021-10-09 11:13:38 -07:00

150 lines
3.5 KiB
C++

// This software implements an Apple ADB interface for a trackball. It uses a
// Teensy 3.2 and is based on the code from this Imgur post https://imgur.com/a/BQjt9le
//
// Revision History
// Initial Release Aug 3, 2021
//
#define ADB_DATA_PIN 5 // TB bidirectional data pin
//
// TB Constants
int ADB_TIMEOUT = 10000;
// TB Functions
static void send_0bit() {
digitalWrite(ADB_DATA_PIN, LOW);
delayMicroseconds(65);
digitalWrite(ADB_DATA_PIN, HIGH);
delayMicroseconds(35);
}
static void send_1bit() {
digitalWrite(ADB_DATA_PIN, LOW);
delayMicroseconds(35);
digitalWrite(ADB_DATA_PIN, HIGH);
delayMicroseconds(65);
}
static void attn() {
//delay(1);
digitalWrite(ADB_DATA_PIN, LOW);
delayMicroseconds(800-35);
send_0bit();
}
void send_talk_command() {
//attn
pinMode(ADB_DATA_PIN, OUTPUT);
attn();
//address (3) 0011
//0
send_0bit();
send_0bit();
send_1bit();
send_1bit();
//talk 11
send_1bit();
send_1bit();
//register 00
send_0bit();
send_0bit();
//stop bit
send_0bit();
//start to stop time
delayMicroseconds(140);
}
int receive_data_packet() {
pinMode(ADB_DATA_PIN, INPUT);
int data_time = 0;
bool command_stop = false;
int adb_data = 0;
//begin reading ADB datapin
while(digitalRead(ADB_DATA_PIN)!=LOW && data_time < ADB_TIMEOUT){
//wait for beginning of start bit
data_time+=1;
delayMicroseconds(1);
}
while(digitalRead(ADB_DATA_PIN)!=HIGH && data_time < ADB_TIMEOUT){
//wait for end of start bit
data_time+=1;
delayMicroseconds(1);
}
while(digitalRead(ADB_DATA_PIN)!=LOW && data_time < ADB_TIMEOUT){
//wait for beginning of first data bit
data_time+=1;
delayMicroseconds(1);
}
//data packet
data_time = 0;
while(!command_stop && data_time < ADB_TIMEOUT) {
int low = 0;
int high = 0;
bool bit_stop = false;
while(!bit_stop && data_time < ADB_TIMEOUT) {
int adb_stream = digitalRead(ADB_DATA_PIN);
if(adb_stream == LOW) low+=1;
if(adb_stream == HIGH) high+=1;
if(adb_stream == LOW && high > 0) bit_stop = true;
if(high > 240){
bit_stop = true;
break;
}
data_time+=1;
delayMicroseconds(1);
}
if(high > 240){
command_stop = true;
}
//append the new data bit to adb_data
if(high > low && !command_stop) adb_data = (adb_data << 1) + 1;
if(low > high && !command_stop) adb_data = adb_data << 1;
}
//stop bit
return adb_data;
}
void parse_data(int data) {
if(data !=0) {
int mousex = data & 0b0000000001111111;
int mousey = (data >> 8) & 0b01111111;
//the mouse value is
//7 bit two's complement
if((mousey & 0b1000000) != 0) {
mousey = ((~mousey + 1) & 0b01111111) * -1;
}
if((mousex & 0b1000000) != 0) {
mousex = ((~mousex + 1) & 0b01111111) * -1;
}
Mouse.move(mousex, mousey);
Mouse.move(mousex, mousey);
int mouseClick = data & 0b1000000000000000;
if(mouseClick == 0) {
Mouse.set_buttons(1,0,0);
}
else if(mouseClick != 0) {
Mouse.set_buttons(0,0,0);
}
}
}
//
//----------------------------------Setup-------------------------------------------
void setup() {
}
//
//---------------------------------Main Loop---------------------------------------------
//
void loop() {
send_talk_command();
parse_data(receive_data_packet());
//
delay(20); //
}