Configure GPIO 16 as power button on Pi and update ATtiny firmware to toggle PA2 on RIGHT+ENTER

Arduino/LIN_to_IR/LIN_to_IR.cpp

@@ -4,6 +4,7 @@
 
 #define IR_ARDUINO_PIN PIN_PA0 // Digital pin 10
 #define LED_PIN        PIN_PA7 // Digital pin 3
+#define RPI_POWER_PIN  PIN_PA2 // GPIO 16 of the RPi is connected to PA2 of the ATtiny
 
 #define RX_PIN         PIN_PB2 // Digital pin 2
 #define TX_PIN         PIN_PB0 // Digital pin 0 (Unused dummy pin or LIN TX)
@@ -17,34 +18,31 @@
 
 SoftwareSerial LINBusSerial(RX_PIN, TX_PIN);
 
-#if defined(TIM1_COMPA_vect) && !defined(TIMER1_COMPA_vect)
-  #define TIMER1_COMPA_vect TIM1_COMPA_vect
-#endif
+void rti_write_byte(uint8_t data) {
+  // Disable interrupts to ensure precise bit-banging timing
+  uint8_t oldSREG = SREG;
+  cli();
 
-volatile uint16_t rti_tx_buffer = 0xFFFF;
-volatile uint8_t rti_tx_bit_count = 0;
+  // Start bit (LOW)
+  digitalWrite(RTI_TX_PIN, LOW);
+  delayMicroseconds(417); // 1 / 2400 baud ≈ 416.67 us
 
-ISR(TIMER1_COMPA_vect) {
-  if (rti_tx_bit_count > 0) {
-    uint8_t bit = rti_tx_buffer & 1;
-    if (bit) {
+  // 8 Data bits (LSB first)
+  for (uint8_t i = 0; i < 8; i++) {
+    if (data & (1 << i)) {
       digitalWrite(RTI_TX_PIN, HIGH);
     } else {
       digitalWrite(RTI_TX_PIN, LOW);
     }
-    rti_tx_buffer >>= 1;
-    rti_tx_bit_count--;
+    delayMicroseconds(417);
   }
-}
 
-void rti_write_byte(uint8_t data) {
-  while (rti_tx_bit_count > 0) {
-    // Wait for the previous byte to finish transmitting
-  }
-  noInterrupts();
-  rti_tx_buffer = 0x200 | (data << 1);
-  rti_tx_bit_count = 10;
-  interrupts();
+  // Stop bit (HIGH)
+  digitalWrite(RTI_TX_PIN, HIGH);
+  delayMicroseconds(417);
+
+  // Restore interrupts
+  SREG = oldSREG;
 }
 
 // RC-6 timing constants
@@ -153,6 +151,26 @@ uint8_t pending_button = 0;
 unsigned long pending_button_time = 0;
 bool button_triggered = false;
 
+// RPi Power control variables and functions
+bool power_button_active = false;
+unsigned long power_button_start_time = 0;
+
+void trigger_power_button() {
+  if (!power_button_active) {
+    pinMode(RPI_POWER_PIN, OUTPUT);
+    digitalWrite(RPI_POWER_PIN, LOW);
+    power_button_active = true;
+    power_button_start_time = millis();
+  }
+}
+
+void update_power_button() {
+  if (power_button_active && (millis() - power_button_start_time >= 150)) {
+    pinMode(RPI_POWER_PIN, INPUT);
+    power_button_active = false;
+  }
+}
+
 void process_button_state(uint8_t active_button) {
   unsigned long now = millis();
   
@@ -168,15 +186,7 @@ void process_button_state(uint8_t active_button) {
           screen_open = !screen_open;
           rti_byte_index = 0; // Reset byte index to send new sequence immediately
         } else if (current_button == 9) {
-          toggle_bit ^= 1;
-          send_ir_for_button(9, toggle_bit);
-          last_ir_send_time = now;
-        }
-      } else if (current_button == 9) {
-        // Repeat sleep command if held
-        if (now - last_ir_send_time >= 250) {
-          send_ir_for_button(9, toggle_bit);
-          last_ir_send_time = now;
+          trigger_power_button();
         }
       }
     } else {
@@ -264,6 +274,9 @@ void setup() {
   pinMode(LED_PIN, OUTPUT);
   digitalWrite(LED_PIN, LOW); // LED OFF
 
+  // Configure RPi power pin (High-Z input initially)
+  pinMode(RPI_POWER_PIN, INPUT);
+
   // Configure RTI TX pin
   pinMode(RTI_TX_PIN, OUTPUT);
   digitalWrite(RTI_TX_PIN, HIGH); // Serial idle is HIGH
@@ -277,14 +290,7 @@ void setup() {
 
   LINBusSerial.begin(9600);
 
-  // Initialize Timer 1 for 2400 Hz CTC interrupts
-  TCCR1A = 0;
-  TCCR1B = 0;
-  TCNT1 = 0;
-  OCR1A = 3332;            // 8,000,000 / (1 * 2400) - 1
-  TCCR1B |= (1 << WGM12);  // CTC mode
-  TCCR1B |= (1 << CS10);   // Prescaler 1
-  TIMSK1 |= (1 << OCIE1A); // Enable interrupt
+  // No timer initialization needed for bit-banging
 
   frame = LinFrame();
   last_frame_time = millis();
@@ -293,6 +299,8 @@ void setup() {
 }
 
 void loop() {
+  update_power_button();
+
   if (LINBusSerial.available()) {
     last_lin_activity_time = millis();
     if (!is_car_on) {
@@ -336,21 +344,19 @@ void loop() {
   if (now - last_rti_send_time >= 100) {
     last_rti_send_time = now;
     
-    uint8_t byte_to_send = 0;
     if (screen_open) {
+      uint8_t byte_to_send = 0;
       // ON sequence: 0x4C (NTSC), 0x2F (max brightness), 0x83 (execute)
       if (rti_byte_index == 0) byte_to_send = 0x4C;
       else if (rti_byte_index == 1) byte_to_send = 0x2F;
       else byte_to_send = 0x83;
+      
+      rti_write_byte(byte_to_send);
+      rti_byte_index = (rti_byte_index + 1) % 3;
     } else {
-      // OFF sequence: 0x46 (OFF), 0x00 (min brightness), 0x83 (execute)
-      if (rti_byte_index == 0) byte_to_send = 0x46;
-      else if (rti_byte_index == 1) byte_to_send = 0x00;
-      else byte_to_send = 0x83;
+      // Stay completely silent on serial when screen is closed to let it retract/close
+      rti_byte_index = 0;
     }
-    
-    rti_write_byte(byte_to_send);
-    rti_byte_index = (rti_byte_index + 1) % 3;
   }
 }
 

Raspberry/config.txt

@@ -83,7 +83,7 @@ dtparam=i2c_arm=on
 dtoverlay=gpio-ir,gpio_pin=24
 
 # Keys
-#dtoverlay=gpio-key,gpio=21,keycode=116,label="POWER"
+dtoverlay=gpio-key,gpio=16,keycode=116,label="POWER"
 #dtoverlay=gpio-key,gpio=26,keycode=115,label="VOLUME_UP"
 #dtoverlay=gpio-key,gpio=20,keycode=114,label="VOLUME_DOWN"