1st functional beta

firmware/ATTINY85_2026_MorseThrowie/ATTINY85_2026_MorseThrowie.ino

@@ -1,103 +1,35 @@
 /*
  =============================================================================
  FireFly Morse Throwie
- - a light controled (LED as Sensor) morseblinker throwie with ATTiny45/85
+ - a light controlled (LED as Sensor) morse blinker throwie with ATTiny85
  =============================================================================
 
  Project definitions, sources
  -----------------------------------------------------------------------------
- Version: 0.1 - Attiny85 Version
+ Version: 0.3 - ATTiny85, 1 MHz, BOD fuse disabled
- Date   : 25.05.2026
+ gitea  : https://gitea.togo-lab.io/tgohle/0001-FireFly
+ Date   : 2026-06-14
 
- -----------------------------------------------------------------------------
+Key changes Version 0.3:
 
- Inspired by Karl Lunt's FireFly project I wrote some code to make this
+- Removed unnecessary ADC enable/disable from loop()
-   Throwie lasting longer, blinking only at low light levels and morse also
+- Disabled ADC and analog comparator in setup()
-   some text.
+- Added INPUT_PULLUP for unused Arduino pins 0, 1, 2 will save power
+- Added safer watchdog setup with interrupt protection to save run near brownout
+- Added wdt_reset() before sleep for cleaner 8 s timing
+- Added lowercase-to-uppercase handling
+- Unsupported characters are now ignored without adding fake timing gaps
+
+-----------------------------------------------------------------------------
+
+Inspired by Karl Lunt's FireFly project:
    http://www.seanet.com/~karllunt/fireflyLED.html
 
- How it works (only the Morsethrowy part):
+ Morse code reference:
-   LED detects light level, using bleeding out time of LED pn-capacitor.
-   If dark enough blink a text in morsecode (ATTiny45 = 22 Chars, text will 
-   be defined in line 191/192 of this file)
-   To save energy go to powersave mode after blinking or light level is
-   over threshold. Tests this every 8s (maximum time for watchdog timer 
-   possible for ATTiny). Repeat this endless
-   
- 
-     The wiring, it's very simple, see also HW part of the Project.
-     
-                     +---+      +------\/------+
-                         |      | ATTINY45 /85 |
-                     >   |     -+1=PB5    VCC=8+-> to SuperCap / DC-DC 3V/5V
-             xxx Ohm <   |      |              |
-                     >   +------+2=PB3    PB2=7+-
-                     |          |              |
-                   ----- +------+3=PB4    PB1=6+-
-             LED    / \  |      |              |
-                   ----- |   +--+4=GND    PB0=5+-
-                     |   |   |  |              |
-                     +---+   |  +--------------+
-                             |
-                             +---------------------> to battery GND
-            
-  You can use other pins if necessary, theoretical up to 3 LEDs, as example I
-  tried out to connect another one at PB2&PB1. working fine. Basic wiring:
- 
-          + LED_N_Side), wired to a digital pin, NOT Vcc
-          |
-          <
-          > 100 - 460 ohm resistor depending Voltage 
-          <
-          |
-          |
-        -----
-         / \  LED, maybe a 5mm, clear plastic is good
-        -----
-          |
-          |
-          + LED_P_Side), wired to a digital pin, NOT Gnd
-
- -----------------------------------------------------------------------------
- Im just a newbe in ATTiny / Arduino programming, so many thanks to:
- 
- Programming ATTiny with Arduino IDE:
-   http://highlowtech.org/?p=1695 
- 
- LED Lightsensor, Arduino Playground:
-   http://playground.arduino.cc/Learning/LEDSensor
-  
- Powersaving Mode for Attiny45/85:
-   A good description by Martin Nawrath nawrath@khm.de and the folks at
-   http://www.insidegadgets.com/2011/02/05/reduce-attiny-power-consumption-by-sleeping-with-the-watchdog-timer/
-   
-   With this description I got ~5uA during sleep mode.
-   in Morse-Mode with LED OFF: 1.7mA 
-                      LED ON:  6.9mA
-   --> I hope to run this throwies ~40days with one CR2032.
-
- Morsecode
-   To translate a text into morsecode, there are several ways. You can use
-   this fine online translator:
-   http://morsecode.scphillips.com/jtranslator.html
- 
-   There is also a great morse coder / encoder from Matthias Esterl aka madc.
-   Works fine for Arduino, but not for ATTiny because of RAM limitations. But
-   maybe this is helpful if your project works with an Arduino.
-   https://gist.github.com/madc/4474559
-
-   For this project I use a simple case structur. Looks arkward, but the
-   ATTiny45 has only 256byte RAM but 4kFlash. A data structure is better programming
-   but needs a lot of RAM we not have. Therefore this ugly case structure.
-   This will waste the flash memory but we have enough and saving RAM for
-   our payload - the ASCII-string with the morsetext.
- 
- BTW - Morsecode itself:
-   
      'A', ".-"      'B', "-..."    'C', "-.-."
      'D', "-.."     'E', "."       'F', "..-."
      'G', "--."     'H', "...."    'I', ".."
-     'J', ".---"    'K', ".-.-"    'L', ".-.."
+     'J', ".---"    'K', "-.-"     'L', ".-.."
      'M', "--"      'N', "-."      'O', "---"
      'P', ".--."    'Q', "--.-"    'R', ".-."
      'S', "..."     'T', "-"       'U', "..-"
@@ -114,25 +46,20 @@
      '(', "-.--."   ')', "-.--.-"  '"', ".-..-."
      '@', ".--.-."  '&', ".-..."
 
- -----------------------------------------------------------------------------
+-----------------------------------------------------------------------------
+
  Legal stuff / Copyright:
-   Creative Commons Attribution ShareAlike 3.0.:
+   License_-_CC_BY-NC_4.0
-   http://creativecommons.org/licenses/by-sa/3.0/legalcode
+   https://creativecommons.org/licenses/by-nc/4.0/
- -----------------------------------------------------------------------------
+-----------------------------------------------------------------------------
 */
 
-
-// ===========================================================================
-// Ok folks, let's start
-// ===========================================================================
-// for sleep Mode / Powersave we need some additional stuff. Its alredy there,
-// if you installed the Attiny extension for Arduino IDE, no additional
-// installing needed.
 #include <avr/sleep.h>
 #include <avr/wdt.h>
+#include <avr/pgmspace.h>
+#include <avr/interrupt.h>
+#include <string.h>
 
-// ===========================================================================
-// Some definitions for powersave depending of ATTiny type.
 #ifndef cbi
 #define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
 #endif
@@ -140,405 +67,325 @@
 #define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
 #endif
 
-// ===========================================================================
+// ---------------------------------------------------------------------------
-// for ATTiny85
+// Timing: unit length in ms.
-// Unit length < 150 will hard to be read for optical morse code
+// At 1 MHz, delay() is accurate when F_CPU=1000000L is set in boards.txt.
-//             > 300 are too slow in my feeling for longer text
+// 100 ms gives readable optical Morse; raise to 150 ms if readability is poor.
-//
-// for ATTiny85 at 8MHz (for 1MHz see ATTiny45)
-// Unit length < 5   will hard to be read for optical morse code
-//             > 10  are too slow in my feeling for longer text
-//
-// 
-
 #define unitLength 100
 
 // ---------------------------------------------------------------------------
-// LED Pin definitions, 
+// Sleep interval.
-// theoretical you can use up to 3 LED. For example you can use it for a
+// Watchdog setup uses 8 s. For final use, change sleepCycles from 4 to 6
-// landmark beacon. So if you point this LEDs to different directions you can 
+// for about 32s - 48s between sensing/blinking activations. Goal ~ 1 blink/min
-// detect the position in dependence of your location to the bacon. 
+const uint8_t sleepCycles = 6;
+
+// ---------------------------------------------------------------------------
+// LED pin definitions (N-side = cathode, P-side = anode for sensing/driving).
 #define LED1_N_SIDE 3
 #define LED1_P_SIDE 4
 
-// ===========================================================================
+// ---------------------------------------------------------------------------
-// Variables
+// ATTiny85 Arduino pins 0, 1, 2 are unused in actual design and physically open.
-// ===========================================================================
+// Keep them in INPUT_PULLUP so they do not float and waste current.
-// ###########################################################################
+#define UNUSED_PIN_0 0
-// # and now the text, but be aware, only 256Byte RAM for Attiny45           #
+#define UNUSED_PIN_1 1
-// # so there are only 22 Chars left for your message.                       #
+#define UNUSED_PIN_2 2
-// # BTW with an Attiny85 you will have additional 256byte                   #
-// # => more than for twitter :-)                                            #
-// # => for FireFly with SuperCap: less ist better, charge last longer       #
 
-String morseText =
+// ---------------------------------------------------------------------------
-     "TOGO LAB";
+// ATTiny85 has 512 bytes SRAM; this keeps the Morse text in flash.
-// # "....5....1....5....2.."; just a ruler, remember 22 Chars for ATTiny #
+// Only uppercase letters, digits, spaces, and the special chars in the switch
-//    IT IS USELESS
+// below are emitted. Lowercase letters are converted to uppercase.
-//    HAIL GLOW CLOUD
+// Test setup: 20 x "0" because 0 = "-----" gives maximum LED ON time for test.
-// ###########################################################################
+// shorter text will better, more text will cost more power.
+const char morseText[] PROGMEM = "TGO 26";
+// Ruler:                         0....0....1...1....2
+// Ruler:                         0....5....0...5....0
+// ---------------------------------------------------------------------------
+// Darkness threshold.
+// Higher value = triggers in brighter conditions.
+// Best calibrated at actual dusk/dawn with the chosen LED type.
+const unsigned int darknessThreshold = 17000;
 
-// Define light trigger threshold. best way to set it on dusk / dawn level
+// ---------------------------------------------------------------------------
-// diffuse red ones are less sensitive than clear green ones...
+// Watchdog interrupt flag — volatile because it is written in an ISR.
-int darknessThreshold = 17000;
+volatile bool f_wdt = true;
 
-// Interrupt Flag, should be volatile, means: read from RAM, not register
+// ---------------------------------------------------------------------------
-// because registers are used for interrupt handling, it have to be volatile.
+// Forward declarations.
-volatile boolean f_wdt = 1;
+void setup_watchdog(uint8_t ii);
+void system_sleep();
+void configureUnusedPins();
+void releaseLedPins(int LED_N, int LED_P);
+unsigned int sensDarkness(int LED_N, int LED_P);
+void morse(int LED_N, int LED_P);
+void dit(int LED_P);
+void dah(int LED_P);
 
 // ===========================================================================
-// Setup watchdog
+// Setup
-// 0=16ms, 1=32ms,2=64ms,3=128ms,4=250ms,5=500ms
-// 6=1 sec,7=2 sec, 8=4 sec, 9= 8sec
 // ===========================================================================
 void setup()
 {
-  setup_watchdog(9);
+  // Disable unused peripherals immediately to save power.
+  // PRTIM1, PRUSI: unused, safe to gate off.
+  // PRADC: ADC is not used; LED sensing is done with digitalRead().
+  // PRTIM0: must stay ON while awake because delay() depends on Timer0.
+  PRR = (1 << PRTIM1) | (1 << PRUSI) | (1 << PRADC);
+
+  // ADC off. It is not needed for digitalRead()-based LED sensing.
+  cbi(ADCSRA, ADEN);
+
+  // Analog comparator off. Saves a little sleep current.
+  ACSR |= (1 << ACD);
+
+  configureUnusedPins();
+  releaseLedPins(LED1_N_SIDE, LED1_P_SIDE);
+
+  setup_watchdog(9);      // 8-second watchdog interval.
 }
 
 // ===========================================================================
-// Main
+// Main loop
 // ===========================================================================
+void loop()
+{
+  if (f_wdt) {
+    f_wdt = false;
 
-void loop(){
+    if (sensDarkness(LED1_N_SIDE, LED1_P_SIDE) > darknessThreshold) {
-
-  if (f_wdt==1) {  // wait for timed out watchdog 
-                   // flag is set when a watchdog timeout occurs
-    f_wdt=0;       // reset flag  
-  
-    // if it's dark enough [>darknesThreshold] morse
-    if (sensDarkness(LED1_N_SIDE, LED1_P_SIDE) > darknessThreshold){
-      // looks like it's dark, so do your job
       morse(LED1_N_SIDE, LED1_P_SIDE);
     }
+
+    // Return LED pins to high-Z before sleeping.
+    // Internal pullups stay disabled for the LED pins.
+    releaseLedPins(LED1_N_SIDE, LED1_P_SIDE);
   }
-  // set all used port to intput to save power
+
-  pinMode(LED1_N_SIDE,INPUT);
+  // Test setup: 1 x 8 s sleep.
-  pinMode(LED1_P_SIDE,INPUT);
+  // Final setup: set sleepCycles = 4 for about 32 s.
-  system_sleep();
+  for (uint8_t i = 0; i < sleepCycles; i++) {
-  f_wdt=0;          // 2nd time sleep
     system_sleep();
+  }
 }
 
 // ===========================================================================
-// Subroutines for Sleeping
+// Pin helpers
 // ===========================================================================
-// set system into the sleep state 
+void configureUnusedPins()
-// system wakes up when wtchdog is timed out
+{
-void system_sleep() {
+  pinMode(UNUSED_PIN_0, INPUT_PULLUP);
-  cbi(ADCSRA,ADEN);                    // switch Analog to 
+  pinMode(UNUSED_PIN_1, INPUT_PULLUP);
-                                       // Digitalconverter OFF
+  pinMode(UNUSED_PIN_2, INPUT_PULLUP);
+}
 
-  set_sleep_mode(SLEEP_MODE_PWR_DOWN); // sleep mode is set here
+void releaseLedPins(int LED_N, int LED_P)
+{
+  // digitalWrite LOW before INPUT disables the internal pullup on Arduino cores.
+  digitalWrite(LED_N, LOW);
+  digitalWrite(LED_P, LOW);
+  pinMode(LED_N, INPUT);
+  pinMode(LED_P, INPUT);
+}
+
+// ===========================================================================
+// Sleep helpers
+// ===========================================================================
+void system_sleep()
+{
+  // Reset watchdog counter so each sleep cycle starts with a fresh interval.
+  wdt_reset();
+
+  set_sleep_mode(SLEEP_MODE_PWR_DOWN);
+
+  // Atomic sleep entry pattern.
+  // After sei(), AVR executes the next instruction before servicing interrupts,
+  // so sleep_cpu() is not skipped by a just-pending interrupt.
+  cli();
   sleep_enable();
+  sei();
+  sleep_cpu();
 
-  sleep_mode();                        // System sleeps here
+  // WDT interrupt wakes the CPU here.
-
+  sleep_disable();
-  sleep_disable();                     // System continues execution here when
-                                       // watchdog timed out 
-  sbi(ADCSRA,ADEN);                    // switch Analog to Digitalconverter ON
 }
 
-// ----------------------------------------------------------------------------
+// Watchdog setup - ii selects timeout:
-// Setup for watchdog. Parameter ii for sleeping time:
+//   0=16ms  1=32ms  2=64ms  3=128ms  4=250ms  5=500ms
-//      0 =  16ms, 1 =  32ms, 2 =  64ms, 
+//   6=1s    7=2s    8=4s    9=8s
-//      3 = 128ms, 4 = 250ms, 5 = 500ms
+void setup_watchdog(uint8_t ii)
-//      6 = 1 sec, 7 = 2 sec, 8 = 4 sec,
+{
-//      9 = 8 sec
+  if (ii > 9) ii = 9;
-void setup_watchdog(int ii) {
 
-  byte bb;
+  uint8_t bb = ii & 7;
-  int ww;
+  if (ii > 7) bb |= (1 << WDP3);
-  if (ii > 9 ) ii=9;
-  bb=ii & 7;
-  if (ii > 7) bb|= (1<<5);
-  bb|= (1<<WDCE);
-  ww=bb;
 
-  MCUSR &= ~(1<<WDRF);
+  uint8_t oldSREG = SREG;
+  cli();
 
-  WDTCR |= (1<<WDCE) | (1<<WDE);       // start timed sequence
+  wdt_reset();
+  MCUSR &= ~(1 << WDRF);
 
-  WDTCR = bb;                          // set new watchdog timeout value
+  // Timed sequence: enable configuration change, then set interrupt-only WDT.
-  WDTCR |= _BV(WDIE);
+  WDTCR |= (1 << WDCE) | (1 << WDE);
-}
+  WDTCR = bb | (1 << WDIE);
-// -----------------------------------------------------------------------------
+
-// Watchdog Interrupt Service / is executed when watchdog timed out
+  SREG = oldSREG;
-ISR(WDT_vect) {
-  f_wdt=1;                             // set global flag
 }
 
-// =============================================================================
+ISR(WDT_vect)
-// Subroutines for light sensor
+{
-// =============================================================================
+  f_wdt = true;
-// Function sensDarkness
+}
-// Usage: sensDarkness(Pin-No. N-Side of LED, Pin-No. P-Side of LED):
-// will result "darkness-level" - the higher the darker:
-//      30000 = pitch black
-//      0     = sunshine
-int sensDarkness(int LED_N, int LED_P){
 
-  unsigned int i;                        //Parameter bleed-out LED capacitor
+// ===========================================================================
+// Light sensor
+// ===========================================================================
+// Returns a "darkness level": higher = darker.
+// Charges the LED junction capacitance, then times how long it takes to bleed
+// back through the reverse-biased LED until the input reads LOW.
+//   ~30000 = pitch black,  ~0 = bright light
+unsigned int sensDarkness(int LED_N, int LED_P)
+{
+  unsigned int i;
 
-  // charge the capacitor of LED  
+  // Charge the LED junction capacitance.
-  pinMode(LED_N,OUTPUT);
+  pinMode(LED_N, OUTPUT);
-  pinMode(LED_P,OUTPUT);
+  pinMode(LED_P, OUTPUT);
-  digitalWrite(LED_N,HIGH);
+  digitalWrite(LED_N, HIGH);
-  digitalWrite(LED_P,LOW);
+  digitalWrite(LED_P, LOW);
 
-  // Isolate the N end of the diode and turn off internal pull-up resistor
+  // Let the N-side float and measure bleed-down time.
-  pinMode(LED_N,INPUT);
+  pinMode(LED_N, INPUT);
-  digitalWrite(LED_N,LOW);
+  digitalWrite(LED_N, LOW);   // disable internal pullup
 
-  // Count how long it takes the diode to bleed back down to a logic zero
+  for (i = 0; i < 30000; i++) {
-  for ( i = 0; i < 30000; i++) {
+    if (digitalRead(LED_N) == LOW) break;
-    if ( digitalRead(LED_N)==0) break;
   }
-  // thats it, return result
+
+  // Clean up after sensing: both LED pins low, then caller releases them.
+  pinMode(LED_N, OUTPUT);
+  digitalWrite(LED_N, LOW);
+  pinMode(LED_P, OUTPUT);
+  digitalWrite(LED_P, LOW);
+
   return i;
 }
 
-// =============================================================================
+// ===========================================================================
-// Subroutines for morse text
+// Morse helpers
-// =============================================================================
+// ===========================================================================
-// -----------------------------------------------------------------------------
+void dit(int LED_P)
-// Function dit = ".", a dit is as long as a unitLength, used in morse()
+{
-//
+  digitalWrite(LED_P, HIGH);
-void dit(int LED_P){
+  delay(unitLength);
-  digitalWrite( LED_P, HIGH ); delay( unitLength );
+  digitalWrite(LED_P, LOW);
-  digitalWrite( LED_P, LOW );  delay( unitLength );
+  delay(unitLength);
 }
 
-// -----------------------------------------------------------------------------
+void dah(int LED_P)
-// Function dah = "-", a dah is as long as a 3*unitLength
+{
-//
+  digitalWrite(LED_P, HIGH);
-void dah(int LED_P){
+  delay(unitLength * 3);
-  digitalWrite( LED_P, HIGH ); delay( unitLength*3 );
+  digitalWrite(LED_P, LOW);
-  digitalWrite( LED_P, LOW );  delay( unitLength );
+  delay(unitLength);
 }
 
-// -----------------------------------------------------------------------------
+// ===========================================================================
-// Function morse:
+// Morse sender
-//   hand over text and LED Pins
+// ===========================================================================
-//   because you want to use more than one LED hand over also LED Pins
+void morse(int LED_N, int LED_P)
+{
+  pinMode(LED_N, OUTPUT);
+  pinMode(LED_P, OUTPUT);
+  digitalWrite(LED_N, LOW);
+  digitalWrite(LED_P, LOW);
 
-void morse(int LED_N, int LED_P){
+  const size_t len = strlen_P(morseText);
 
-  // Because I have more Flash than RAM I decided to use a case structure.
+  for (size_t i = 0; i < len; i++) {
-  // Its not so pretty, but I can use the RAM to hold my morseText.
+    char c = (char)pgm_read_byte(&morseText[i]);
-  //
-  // set N-Side of LED Low, so you can set P-side high to let them flash
 
-  pinMode( LED_N, OUTPUT);
+    // Allow lowercase source text without silently breaking timing.
-  pinMode( LED_P, OUTPUT);
+    if (c >= 'a' && c <= 'z') {
-
+      c = c - 'a' + 'A';
-  digitalWrite( LED_N, LOW);
-
-  // send it to defined LED
-  for(int i=0; i<=morseText.length(); i++)
-  {
-    switch( morseText[i] )
-    {            
- 
-    // Chars A-Z
-    case 'A': // .-
-      dit(LED_P); dah(LED_P);
-      break;
- 
-    case 'B': // -...
-      dah(LED_P); dit(LED_P); dit(LED_P); dit(LED_P);
-      break;
-
-    case 'C': // -.-.
-      dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); 
-      break;
-
-    case 'D': // -..
-      dah(LED_P); dit(LED_P); dit(LED_P); 
-      break; 
-
-    case 'E': // .
-      dit(LED_P);
-      break; 
-
-    case 'F': // ..-.
-      dit(LED_P); dit(LED_P); dah(LED_P); dit(LED_P);
-      break; 
-
-    case 'G': // --.
-      dah(LED_P); dah(LED_P); dit(LED_P); 
-      break; 
-
-    case 'H': // ....
-      dit(LED_P); dit(LED_P); dit(LED_P); dit(LED_P);
-      break; 
-
-    case 'I': // ..
-      dit(LED_P); dit(LED_P);
-      break; 
-
-    case 'J': // .---
-      dit(LED_P); dah(LED_P); dah(LED_P); dah(LED_P);
-      break; 
-
-    case 'K': // .-.-
-      dit(LED_P); dah(LED_P); dit(LED_P); dah(LED_P);
-      break; 
-
-    case 'L': // .-..
-      dit(LED_P); dah(LED_P); dit(LED_P); dit(LED_P);
-      break; 
-
-    case 'M': // --
-       dah(LED_P); dah(LED_P);
-      break; 
-
-    case 'N': // -.
-      dah(LED_P); dit(LED_P);
-      break; 
-
-    case 'O': // ---
-      dah(LED_P); dah(LED_P); dah(LED_P);
-      break; 
-
-    case 'P': // .--.
-      dit(LED_P); dah(LED_P); dah(LED_P); dit(LED_P);
-      break; 
-
-    case 'Q': // --.-
-      dah(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); 
-      break; 
-
-    case 'R': // .-.
-      dit(LED_P); dah(LED_P); dit(LED_P);
-      break; 
-      
-    case 'S': // ...
-      dit(LED_P); dit(LED_P); dit(LED_P);
-      break;       
-
-    case 'T': // -
-      dah(LED_P);
-      break; 
-
-    case 'U': // ..-
-      dit(LED_P); dit(LED_P); dah(LED_P);
-      break; 
-
-    case 'V': // ...-
-      dit(LED_P); dit(LED_P); dit(LED_P); dah(LED_P);
-      break; 
-
-    case 'W': // .--
-      dit(LED_P); dah(LED_P); dah(LED_P);
-      break; 
-
-    case 'X': // -..-
-       dah(LED_P); dit(LED_P); dit(LED_P); dah(LED_P);
-      break; 
-
-    case 'Y': // -.--
-       dah(LED_P); dit(LED_P); dah(LED_P); dah(LED_P);
-      break; 
-
-    case 'Z': // --..
-      dah(LED_P);dah(LED_P); dit(LED_P); dit(LED_P);
-      break; 
-
-    // Numbers
-    case '1': // .----
-      dit(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); dah(LED_P);
-      break; 
-
-    case '2': // ..---
-      dit(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); dah(LED_P);
-      break; 
-
-    case '3': // ...--
-      dit(LED_P); dit(LED_P); dit(LED_P); dah(LED_P); dah(LED_P);
-      break; 
-
-    case '4': // ....-
-      dit(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); dah(LED_P);
-      break; 
-
-    case '5': // .....
-      dit(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); dit(LED_P);
-      break; 
-
-    case '6': // -....
-      dah(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); 
-      break; 
-
-    case '7': // --...
-      dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); 
-      break; 
-
-    case '8': // ---..
-      dah(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); 
-      break; 
-
-    case '9': // ----.
-      dah(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); 
-      break; 
-
-    case '0': // -----
-      dah(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); 
-      break; 
-
-    // Special Signs
-    case ' ': // Gap
-        delay( unitLength*5 );
-      break; 
-
-    case '.': // .-.-.-
-      dit(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); dah(LED_P);
-      break; 
-
-    case ',': // --..--
-      dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); dah(LED_P); dah(LED_P);
-      break; 
-
-    case '?': // ..--..
-      dit(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P);
-      break; 
-
-    case '!': // -.-.--
-      dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); dah(LED_P);
-      break; 
-
-    case ':': // ---...
-      dah(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); dit(LED_P);
-      break; 
-
-    case ';': // -.-.-.
-      dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P);
-      break; 
-
-    case '(': // -.--.
-      dah(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); dit(LED_P);
-      break; 
-
-    case ')': // -.--.-
-      dah(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); dah(LED_P);
-      break; 
-
-    case '"': // .-..-.
-      dit(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); dah(LED_P); dit(LED_P);
-      break; 
-
-    case '@': // .--.-.
-      dit(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P);
-      break; 
-
-    case '&': // .-...
-      dit(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); dit(LED_P);
     }
-    // wait at end of sign 
-    delay( unitLength*3 );
-  }
-}
 
-// -----------------------------------------------------------------------------
+    bool symbolSent = false;
-// That's all, folks :-)
+
-// -----------------------------------------------------------------------------
+    switch (c)
+    {
+    // ----- Letters -----
+    case 'A': dit(LED_P); dah(LED_P); symbolSent = true; break;                                      // .-
+    case 'B': dah(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); symbolSent = true; break;              // -...
+    case 'C': dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); symbolSent = true; break;              // -.-.
+    case 'D': dah(LED_P); dit(LED_P); dit(LED_P); symbolSent = true; break;                          // -..
+    case 'E': dit(LED_P); symbolSent = true; break;                                                  // .
+    case 'F': dit(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); symbolSent = true; break;              // ..-.
+    case 'G': dah(LED_P); dah(LED_P); dit(LED_P); symbolSent = true; break;                          // --.
+    case 'H': dit(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); symbolSent = true; break;              // ....
+    case 'I': dit(LED_P); dit(LED_P); symbolSent = true; break;                                      // ..
+    case 'J': dit(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); symbolSent = true; break;              // .---
+    case 'K': dah(LED_P); dit(LED_P); dah(LED_P); symbolSent = true; break;                          // -.-
+    case 'L': dit(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); symbolSent = true; break;              // .-..
+    case 'M': dah(LED_P); dah(LED_P); symbolSent = true; break;                                      // --
+    case 'N': dah(LED_P); dit(LED_P); symbolSent = true; break;                                      // -.
+    case 'O': dah(LED_P); dah(LED_P); dah(LED_P); symbolSent = true; break;                          // ---
+    case 'P': dit(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); symbolSent = true; break;              // .--.
+    case 'Q': dah(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); symbolSent = true; break;              // --.-
+    case 'R': dit(LED_P); dah(LED_P); dit(LED_P); symbolSent = true; break;                          // .-.
+    case 'S': dit(LED_P); dit(LED_P); dit(LED_P); symbolSent = true; break;                          // ...
+    case 'T': dah(LED_P); symbolSent = true; break;                                                  // -
+    case 'U': dit(LED_P); dit(LED_P); dah(LED_P); symbolSent = true; break;                          // ..-
+    case 'V': dit(LED_P); dit(LED_P); dit(LED_P); dah(LED_P); symbolSent = true; break;              // ...-
+    case 'W': dit(LED_P); dah(LED_P); dah(LED_P); symbolSent = true; break;                          // .--
+    case 'X': dah(LED_P); dit(LED_P); dit(LED_P); dah(LED_P); symbolSent = true; break;              // -..-
+    case 'Y': dah(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); symbolSent = true; break;              // -.--
+    case 'Z': dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); symbolSent = true; break;              // --..
+
+    // ----- Digits -----
+    case '1': dit(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); symbolSent = true; break;  // .----
+    case '2': dit(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); symbolSent = true; break;  // ..---
+    case '3': dit(LED_P); dit(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); symbolSent = true; break;  // ...--
+    case '4': dit(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); dah(LED_P); symbolSent = true; break;  // ....-
+    case '5': dit(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); symbolSent = true; break;  // .....
+    case '6': dah(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); symbolSent = true; break;  // -....
+    case '7': dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); symbolSent = true; break;  // --...
+    case '8': dah(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); symbolSent = true; break;  // ---..
+    case '9': dah(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); symbolSent = true; break;  // ----.
+    case '0': dah(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); symbolSent = true; break;  // -----
+
+    // ----- Punctuation -----
+    case '.': dit(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); symbolSent = true; break;  // .-.-.-
+    case ',': dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); symbolSent = true; break;  // --..--
+    case '?': dit(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); symbolSent = true; break;  // ..--..
+    case '!': dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); symbolSent = true; break;  // -.-.--
+    case ':': dah(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); symbolSent = true; break;  // ---...
+    case ';': dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); symbolSent = true; break;  // -.-.-.
+    case '(': dah(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); symbolSent = true; break;              // -.--.
+    case ')': dah(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); symbolSent = true; break;  // -.--.-
+    case '"': dit(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); symbolSent = true; break;  // .-..-.
+    case '@': dit(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); symbolSent = true; break;  // .--.-.
+    case '&': dit(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); symbolSent = true; break;              // .-...
+
+    // Space handling:
+    // Previous symbol already ended with 1 unit OFF and then received the
+    // normal 2 unit character gap. Add 4 units here -> total word gap 7 units.
+    case ' ':
+      delay(unitLength * 4);
+      break;
+
+    // Unsupported chars are ignored without adding an artificial gap.
+    default:
+      break;
+    }
+
+    // Inter-character gap: 3 units total.
+    // dit()/dah() already trail 1 unit OFF, so add the remaining 2 units.
+    if (symbolSent) {
+      delay(unitLength * 2);
+    }
+  }
+
+  digitalWrite(LED_P, LOW);
+  digitalWrite(LED_N, LOW);
+}

firmware/archive/ATTINY85_2026_MorseThrowie 2.0/ATTINY85_2026_MorseThrowie 2.0.ino

@@ -0,0 +1,311 @@
+/*
+ =============================================================================
+ FireFly Morse Throwie 
+ - a light controlled (LED as Sensor) morse blinker throwie with ATTiny85
+ ============================================================================= 
+ 
+ Project definitions, sources
+ ----------------------------------------------------------------------------- 
+ Version: 0.2 - ATTiny85, 1 MHz, BOD fuse disabled
+ gitea  : https://gitea.togo-lab.io/tgohle/0001-FireFly
+ Date   : 2026-06-13
+ 
+ -----------------------------------------------------------------------------
+
+ Inspired by Karl Lunt's FireFly project:
+   http://www.seanet.com/~karllunt/fireflyLED.html
+
+ Morse code reference:
+     'A', ".-"      'B', "-..."    'C', "-.-."
+     'D', "-.."     'E', "."       'F', "..-."
+     'G', "--."     'H', "...."    'I', ".."
+     'J', ".---"    'K', "-.-"     'L', ".-.."
+     'M', "--"      'N', "-."      'O', "---"
+     'P', ".--."    'Q', "--.-"    'R', ".-."
+     'S', "..."     'T', "-"       'U', "..-"
+     'V', "...-"    'W', ".--"     'X', "-..-"
+     'Y', "-.--"    'Z', "--.."    
+
+     '1', ".----"   '2', "..---"   '3', "...--"
+     '4', "....-"   '5', "....."   '6', "-...."
+     '7', "--..."   '8', "---.."   '9', "----."
+     '0', "-----"
+
+     '.', ".-.-.-"  ',', "--..--"  '?', "..--.."
+     '!', "-.-.--"  ':', "---..."  ';', "-.-.-."
+     '(', "-.--."   ')', "-.--.-"  '"', ".-..-."
+     '@', ".--.-."  '&', ".-..."
+
+ Legal stuff / Copyright:
+   License_-_CC_BY-NC_4.0
+   https://creativecommons.org/licenses/by-nc/4.0/
+ -----------------------------------------------------------------------------
+*/
+
+#include <avr/sleep.h>
+#include <avr/wdt.h>
+#include <avr/pgmspace.h>    // FIX 3: needed for PROGMEM / pgm_read_byte
+
+#ifndef cbi
+#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
+#endif
+#ifndef sbi
+#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
+#endif
+
+// ---------------------------------------------------------------------------
+// Timing: unit length in ms.
+// At 1 MHz, delay() is accurate when F_CPU=1000000L is set in boards.txt.
+// 100 ms gives readable optical Morse; raise to 150 if readability is poor.
+#define unitLength 100
+
+// ---------------------------------------------------------------------------
+// LED pin definitions (N-side = cathode, P-side = anode for sensing/driving)
+#define LED1_N_SIDE 3
+#define LED1_P_SIDE 4
+
+// ---------------------------------------------------------------------------
+// ATTiny85 has 512 bytes SRAM; this frees all of it for the stack.
+// Only uppercase letters, digits, and the special chars in the switch below.
+// Test only: 20 x "0" due 0 = "-----" most energy draining
+const char morseText[] PROGMEM = "0000000000000000000";
+// Ruler:                         0...0....1...1....2  Attention: more Text 
+// Ruler:                         1...5....0...5....0  will cost more power!
+
+
+// ---------------------------------------------------------------------------
+// Darkness threshold.
+// Higher value = triggers in brighter conditions.
+// Best calibrated at actual dusk/dawn with the chosen LED type.
+unsigned int darknessThreshold = 17000;
+
+// ---------------------------------------------------------------------------
+// Watchdog interrupt flag — volatile because it is written in an ISR
+volatile boolean f_wdt = 1;
+
+// ---------------------------------------------------------------------------
+// Forward declarations
+void setup_watchdog(int ii);
+void system_sleep();
+unsigned int sensDarkness(int LED_N, int LED_P);
+void morse(int LED_N, int LED_P);
+void dit(int LED_P);
+void dah(int LED_P);
+
+// ===========================================================================
+// Setup
+// ===========================================================================
+void setup()
+{
+  // Disable unused peripherals immediately to save some µ/mA.
+  // PRTIM1, PRUSI: genuinely unused, safe to gate off
+  // PRADC: controlled manually around sensDarkness()
+  // PRTIM0: must stay ON — delay() and millis() depend on Timer0
+  PRR = (1 << PRTIM1) | (1 << PRUSI) | (1 << PRADC);
+
+  // ADC is gated via PRR above; also clear ADEN just in case
+  cbi(ADCSRA, ADEN);
+
+  setup_watchdog(9);      // 8-second watchdog interval
+                          // simple repeat if more delay is need, eg 4
+}
+
+// ===========================================================================
+// Main loop
+// ===========================================================================
+void loop()
+{
+  if (f_wdt == 1) {
+    f_wdt = 0;
+
+    // Enable ADC only for the sensing window, then shut it off again.
+    cbi(PRR, PRADC);          // un-gate ADC clock
+    sbi(ADCSRA, ADEN);        // power ADC on
+
+    if (sensDarkness(LED1_N_SIDE, LED1_P_SIDE) > darknessThreshold) {
+      morse(LED1_N_SIDE, LED1_P_SIDE);
+    }
+
+    cbi(ADCSRA, ADEN);        // ADC off
+    sbi(PRR, PRADC);          // re-gate ADC clock
+
+    // Return LED pins to input (high-Z) before sleeping
+    pinMode(LED1_N_SIDE, INPUT);
+    pinMode(LED1_P_SIDE, INPUT);
+  }
+
+  // sleep 4 x 8 s = ~32 s between activations
+  for (uint8_t i = 0; i < 1; i++) {
+    system_sleep();
+  }
+  // f_wdt is set to 1 by the WDT ISR when the 8 s expire; no manual clear needed here.
+}
+
+// ===========================================================================
+// Sleep helpers
+// ===========================================================================
+
+void system_sleep()
+{
+  set_sleep_mode(SLEEP_MODE_PWR_DOWN);
+  sleep_enable();
+  sleep_mode();          // CPU halts here until WDT fires
+  sleep_disable();
+  // ADC stays off - re-enable it in loop() only when sensing
+}
+
+// Watchdog setup - ii selects timeout:
+//   0=16ms  1=32ms  2=64ms  3=128ms  4=250ms  5=500ms
+//   6=1s    7=2s    8=4s    9=8s
+void setup_watchdog(int ii)
+{
+  byte bb;
+  if (ii > 9) ii = 9;
+  bb = ii & 7;
+  if (ii > 7) bb |= (1 << 5);
+  bb |= (1 << WDCE);
+
+  MCUSR &= ~(1 << WDRF);
+  WDTCR |= (1 << WDCE) | (1 << WDE);   // timed sequence - must not be split
+  WDTCR = bb;
+  WDTCR |= _BV(WDIE);
+}
+
+ISR(WDT_vect)
+{
+  f_wdt = 1;
+}
+
+// ===========================================================================
+// Light sensor
+// ===========================================================================
+// Returns a "darkness level": higher = darker.
+// Charges the LED junction capacitor, then times how long it takes to bleed
+// back through the reverse-biased diode to a logic LOW.
+//   ~30000 = pitch black,  ~0 = bright light
+
+// return type is unsigned int (counter can reach 30000, fits in 16 bits)
+unsigned int sensDarkness(int LED_N, int LED_P)
+{
+  unsigned int i;
+
+  // Charge the LED (forward-bias momentarily)
+  pinMode(LED_N, OUTPUT);
+  pinMode(LED_P, OUTPUT);
+  digitalWrite(LED_N, HIGH);
+  digitalWrite(LED_P, LOW);
+
+  // Let the N-end float and measure bleed-down time
+  pinMode(LED_N, INPUT);
+  digitalWrite(LED_N, LOW);   // disable internal pull-up
+
+  for (i = 0; i < 30000; i++) {
+    if (digitalRead(LED_N) == 0) break;
+  }
+
+  // clean up after sensing
+  pinMode(LED_N, OUTPUT);
+  digitalWrite(LED_N, LOW);
+  pinMode(LED_P, OUTPUT);
+  digitalWrite(LED_P, LOW);
+  return i;
+
+}
+
+// ===========================================================================
+// Morse helpers
+// ===========================================================================
+
+void dit(int LED_P)
+{
+  digitalWrite(LED_P, HIGH); delay(unitLength);
+  digitalWrite(LED_P, LOW);  delay(unitLength);
+}
+
+void dah(int LED_P)
+{
+  digitalWrite(LED_P, HIGH); delay(unitLength * 3);
+  digitalWrite(LED_P, LOW);  delay(unitLength);
+}
+
+// ===========================================================================
+// Morse sender
+// ===========================================================================
+void morse(int LED_N, int LED_P)
+{
+  pinMode(LED_N, OUTPUT);
+  pinMode(LED_P, OUTPUT);
+  digitalWrite(LED_N, LOW);
+
+  // read each character from flash with pgm_read_byte()
+  // use < morseText length, not <=  (avoids reading past the null terminator)
+  uint8_t len = strlen_P(morseText);
+  for (uint8_t i = 0; i < len; i++)
+  {
+    char c = (char)pgm_read_byte(&morseText[i]);
+
+    switch (c)
+    {
+    // ----- Letters -----
+    case 'A': dit(LED_P); dah(LED_P); break;                                         // .-
+    case 'B': dah(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); break;                 // -...
+    case 'C': dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); break;                 // -.-.
+    case 'D': dah(LED_P); dit(LED_P); dit(LED_P); break;                             // -..
+    case 'E': dit(LED_P); break;                                                      // .
+    case 'F': dit(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); break;                 // ..-.
+    case 'G': dah(LED_P); dah(LED_P); dit(LED_P); break;                             // --.
+    case 'H': dit(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); break;                 // ....
+    case 'I': dit(LED_P); dit(LED_P); break;                                         // ..
+    case 'J': dit(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); break;                 // .---
+    case 'K': dah(LED_P); dit(LED_P); dah(LED_P); break;                             // -.-
+    case 'L': dit(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); break;                 // .-..
+    case 'M': dah(LED_P); dah(LED_P); break;                                         // --
+    case 'N': dah(LED_P); dit(LED_P); break;                                         // -.
+    case 'O': dah(LED_P); dah(LED_P); dah(LED_P); break;                             // ---
+    case 'P': dit(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); break;                 // .--.
+    case 'Q': dah(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); break;                 // --.-
+    case 'R': dit(LED_P); dah(LED_P); dit(LED_P); break;                             // .-.
+    case 'S': dit(LED_P); dit(LED_P); dit(LED_P); break;                             // ...
+    case 'T': dah(LED_P); break;                                                     // -
+    case 'U': dit(LED_P); dit(LED_P); dah(LED_P); break;                             // ..-
+    case 'V': dit(LED_P); dit(LED_P); dit(LED_P); dah(LED_P); break;                 // ...-
+    case 'W': dit(LED_P); dah(LED_P); dah(LED_P); break;                             // .--
+    case 'X': dah(LED_P); dit(LED_P); dit(LED_P); dah(LED_P); break;                 // -..-
+    case 'Y': dah(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); break;                 // -.--
+    case 'Z': dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); break;                 // --..
+
+    // ----- Digits -----
+    case '1': dit(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); break;     // .----
+    case '2': dit(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); break;     // ..---
+    case '3': dit(LED_P); dit(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); break;     // ...--
+    case '4': dit(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); dah(LED_P); break;     // ....-
+    case '5': dit(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); break;     // .....
+    case '6': dah(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); break;     // -....
+    case '7': dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); break;     // --...
+    case '8': dah(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); break;     // ---.
+    case '9': dah(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); break;     // ----.
+    case '0': dah(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); dah(LED_P); break;     // -----
+
+    // ----- Punctuation -----
+    case ' ': delay(unitLength * 5); break;                                           // word gap (5 + 3 = 8 units total)
+    case '.': dit(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); break;  // .-.-.-
+    case ',': dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); break;  // --..--
+    case '?': dit(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); break;  // ..--..
+    case '!': dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); break;  // -.-.--
+    case ':': dah(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); break;  // ---...
+    case ';': dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); break;  // -.-.-.
+    case '(': dah(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); break;              // -.--.
+    case ')': dah(LED_P); dit(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); break;  // -.--.-
+    case '"': dit(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); break;  // .-..-.
+    case '@': dit(LED_P); dah(LED_P); dah(LED_P); dit(LED_P); dah(LED_P); dit(LED_P); break;  // .--.-.
+    case '&': dit(LED_P); dah(LED_P); dit(LED_P); dit(LED_P); dit(LED_P); break;              // .-...
+    }
+
+    // Inter-character gap: 3 units (the dit/dah functions already trail 1 unit,
+    // so this adds the remaining 2 to reach the standard 3-unit gap).
+    // Space case already handles word gap - no extra delay needed there.
+    if (c != ' ') {
+      delay(unitLength * 2);
+    }
+  }
+}