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cdtv.cpp
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cdtv.cpp
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/*
Uses:
Timer1 (OCR1A) to generate CDTV serial protocol.
The CDTV IR protocol uses a 40kHz carrier when transmitting.
It sends a 9ms start pulse followed by a 4.5ms pause.
Then it sends 12 bits, each consisting of a 400us pulse, then
a 400us (for a 0 bit) or 1200us (for a 1 bit) pause. It then sends
the same 12 bits inversed. Finally a 400us pulse is sent.
Total = 9000 + 4500 + 24 * 1200 + 400 = 42700 us
Rest = 60000 - 42700 = 17300 us
If a button is held. It sends 'repeat' code every 60ms which is a 9ms
pulse, followed by a 2.1ms pause and lastly a 400us pulse.
Total = 9000 + 2100 + 400 = 11500 us
Rest = 60000 - 11500 = 48500 us
This work was built on information gathered from:
http://www.amiga.org/forums/archive/index.php/t-60087.html
https://github.com/hkzlab/AVR-Experiments/tree/master/samples/m128-ir-cdtv
CD-1253 Mouse uses another simple asynchronous serial protocol over the
same (PRDT) line.
This was reverese engineered by myself (matsstaff)
Startbit: pull low 1100us, release 375us
Data (19 bits): low 500us, release 375us (sending a 1)
low 138us, release 735us (sending a 0)
Stop bit: pull low 88us, release
The data (19 bits) is send MSB first
first bit is unknown (always one), might be reserved for middle button
second bit is right mouse button, 1 = released, 0 = pressed
third bit is left mouse button, 1 = released, 0 = pressed
then 8 bits signed horizontal movement, negative = right, positive = left
last 8 bits signed vertical movement, negative = down , positive = up
Packets are sent every ~32ms when movement occurs, each packet is approx
18ms, so there's a ~14ms gap between packets.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "Arduino.h"
#include "cdtv.h"
#define PRDTPIN 7
#define BUFSIZE 16
static volatile int8_t head=0, tail=0;
static uint16_t irbuf[BUFSIZE];
static inline void weak_pullup(int pin) {
pinMode(pin, INPUT);
digitalWrite(pin, HIGH);
}
static inline void pull_down(int pin){
digitalWrite(pin, LOW);
pinMode(pin, OUTPUT);
}
void cdtv_init(){
// init datapin
weak_pullup(PRDTPIN);
// init joystick
weak_pullup(A0); // right
weak_pullup(A1); // left
weak_pullup(A2); // down
weak_pullup(A3); // up
weak_pullup(A4); // b
weak_pullup(A5); // a
PCMSK1 |= (1 << PCINT13) | (1 << PCINT12) | (1 << PCINT11) | (1 << PCINT10) | (1 << PCINT9) | (1 << PCINT8);
PCICR |= (1 << PCIE1); // Enable pinchange interrupt
// Setup timer1 to generate timer interrupts (CTC mode)
TCCR1A = 0;
TCCR1B = 0;
TCNT1 = 0;
OCR1A = 0x20; // compare match register 16MHz/8
TCCR1B |= (1 << WGM12); // CTC mode
// TCCR1B |= (1 << CS11); // 8 prescaler (but start disabled)
TIMSK1 |= (1 << OCIE1A); // enable timer compare interrupt
}
// Joystick interrupt
ISR(PCINT1_vect) {
TCCR1B |= (1 << CS11); // Make sure timer is enabled
}
uint16_t joystick_get_state(){
uint8_t joy_s = (~PINC & 0x3F);
return joy_s ? (0x800UL | (joy_s<<2)) : 0;
}
static volatile int16_t mouse_x=0, mouse_y=0;
static volatile uint8_t mouse_buttons=0;
uint8_t mouse_set_state(uint8_t buttons, int8_t x, int8_t y) {
noInterrupts();
mouse_x = mouse_x - (mouse_x >> 1) + x; // Leaky integration
mouse_y = mouse_y - (mouse_y >> 1) + y;
mouse_buttons |= buttons;
interrupts();
TCCR1B |= (1 << CS11); // Make sure timer is enabled
}
/* Called from timer interrupt */
uint8_t mouse_get_state(uint32_t *ms) {
uint8_t mx = -mouse_x; //invert
uint8_t my = -mouse_y;
uint8_t rv = mouse_buttons || mx || my;
*ms = (((uint32_t)(mouse_buttons ^ 0x7)) << 16) | ((uint16_t)mx) << 8 | my;
// Reset mouse state
mouse_x=0;
mouse_y=0;
mouse_buttons=0;
return rv;
}
enum transmitstates {
tx_idle=0,
ir_start,
ir_transmit, // 2
ir_end_pulse=ir_transmit+48, // 50
ir_stop,
ir_repeat,
ir_repeat_end_pulse,
ir_repeat_stop,
ir_repeat_stop2,
m_start, // 56
m_transmit, // 57
m_stop=m_transmit+38,
m_stop2
};
ISR(TIMER1_COMPA_vect) {
static uint16_t joy_state=0;
static uint8_t tx_state=0;
static uint32_t mouse=0;
if(tx_state == tx_idle){
uint16_t new_joy_state = joystick_get_state();
if(new_joy_state || joy_state){
tx_state = (new_joy_state == joy_state) ? ir_repeat : ir_start;
joy_state = new_joy_state;
pull_down(PRDTPIN);
OCR1A=18000; // 9ms start pulse
TCNT1 = 0;
} else if(mouse_get_state(&mouse)) {
tx_state = m_start;
pull_down(PRDTPIN);
OCR1A=2200; // 1.1ms start pulse
TCNT1 = 0;
} else {
TCCR1B &= ~(1 << CS11); // disable timer
}
} else if(tx_state < m_start) { // PAD
if(tx_state == ir_start){
weak_pullup(PRDTPIN);
OCR1A = 9000; // 4.5ms pause
tx_state++;
}
else if(tx_state<ir_end_pulse){
uint8_t ss = tx_state - ir_transmit;
if((ss & 0x1) == 0){ // Pulse
pull_down(PRDTPIN);
OCR1A = 800;
} else { // Pause
weak_pullup(PRDTPIN);
ss = ss >> 1;
if(ss >= 12){
ss -= 12;
}
ss = 11 - ss;
if(tx_state > ir_transmit + 24){
OCR1A = (joy_state>>ss & 0x1) ? 800 : 2400;
} else {
OCR1A = (joy_state>>ss & 0x1) ? 2400 : 800;
}
}
tx_state++;
}
else if(tx_state==ir_end_pulse){
pull_down(PRDTPIN);
OCR1A = 800;
tx_state++;
}
else if(tx_state==ir_stop){
weak_pullup(PRDTPIN);
OCR1A = 34600; // Allow some space
tx_state = tx_idle;
}
else if(tx_state==ir_repeat){
weak_pullup(PRDTPIN);
OCR1A = 4200; // pause
tx_state++;
}
else if(tx_state==ir_repeat_end_pulse){
pull_down(PRDTPIN);
OCR1A = 800;
tx_state++;
}
else if(tx_state==ir_repeat_stop){
weak_pullup(PRDTPIN);
OCR1A = 48500; // Allow some space
tx_state++;
}
else if(tx_state==ir_repeat_stop2){
OCR1A = 48500; // Allow some space
tx_state = tx_idle;
}
} else { // MOUSE
if(tx_state == m_start){
weak_pullup(PRDTPIN);
OCR1A = 750; // 375us pause
tx_state++;
} else if(tx_state < m_stop) {
uint8_t ss = tx_state - m_transmit; // ss goes from 0 to 37
uint8_t bitv = (mouse >> (18 - (ss >> 1))) & 0x1;
if((ss & 0x1) == 0){ // Pulse
pull_down(PRDTPIN);
OCR1A = bitv ? 1000 : 276;
} else { // pause
weak_pullup(PRDTPIN);
OCR1A = bitv ? 750 : 1470;
}
tx_state++;
} else if(tx_state == m_stop){
pull_down(PRDTPIN);
OCR1A = 176; // 88us stop pulse
tx_state++;
} else { // m_stop2
weak_pullup(PRDTPIN);
OCR1A = 28000; // 14ms pause
tx_state = tx_idle;
}
}
}