Version 3 sleeping behavior bugs, morsehandling bugs and timing bugs especially near BOD

firmware/ATTINY85_2026_MorseThrowie/ATTINY85_2026_MorseThrowie.ino

@@ -0,0 +1,391 @@
+/*
+ =============================================================================
+ FireFly Morse Throwie
+ - a light controlled (LED as Sensor) morse blinker throwie with ATTiny85
+ =============================================================================
+
+ Project definitions, sources
+ -----------------------------------------------------------------------------
+ Version: 0.3 - ATTiny85, 1 MHz, BOD fuse disabled
+ gitea  : https://gitea.togo-lab.io/tgohle/0001-FireFly
+ Date   : 2026-06-14
+
+Key changes Version 0.3:
+
+- Removed unnecessary ADC enable/disable from loop()
+- Disabled ADC and analog comparator in setup()
+- 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
+
+ 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>
+#include <avr/interrupt.h>
+#include <string.h>
+
+#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 ms if readability is poor.
+#define unitLength 100
+
+// ---------------------------------------------------------------------------
+// Sleep interval.
+// Watchdog setup uses 8 s. For final use, change sleepCycles from 1 to 4
+// for about 32 s between sensing/blinking activations.
+const uint8_t sleepCycles = 4;
+
+// ---------------------------------------------------------------------------
+// LED pin definitions (N-side = cathode, P-side = anode for sensing/driving).
+#define LED1_N_SIDE 3
+#define LED1_P_SIDE 4
+
+// ---------------------------------------------------------------------------
+// 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
+#define UNUSED_PIN_1 1
+#define UNUSED_PIN_2 2
+
+// ---------------------------------------------------------------------------
+// ATTiny85 has 512 bytes SRAM; this keeps the Morse text in flash.
+// Only uppercase letters, digits, spaces, and the special chars in the switch
+// below are emitted. Lowercase letters are converted to uppercase.
+// 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 = "TOGO LAB";
+// 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;
+
+// ---------------------------------------------------------------------------
+// Watchdog interrupt flag — volatile because it is written in an ISR.
+volatile bool f_wdt = true;
+
+// ---------------------------------------------------------------------------
+// Forward declarations.
+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
+// ===========================================================================
+void setup()
+{
+  // 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 loop
+// ===========================================================================
+void loop()
+{
+  if (f_wdt) {
+    f_wdt = false;
+
+    if (sensDarkness(LED1_N_SIDE, LED1_P_SIDE) > darknessThreshold) {
+      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);
+  }
+
+  // Test setup: 1 x 8 s sleep.
+  // Final setup: set sleepCycles = 4 for about 32 s.
+  for (uint8_t i = 0; i < sleepCycles; i++) {
+    system_sleep();
+  }
+}
+
+// ===========================================================================
+// Pin helpers
+// ===========================================================================
+void configureUnusedPins()
+{
+  pinMode(UNUSED_PIN_0, INPUT_PULLUP);
+  pinMode(UNUSED_PIN_1, INPUT_PULLUP);
+  pinMode(UNUSED_PIN_2, INPUT_PULLUP);
+}
+
+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();
+
+  // WDT interrupt wakes the CPU here.
+  sleep_disable();
+}
+
+// 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(uint8_t ii)
+{
+  if (ii > 9) ii = 9;
+
+  uint8_t bb = ii & 7;
+  if (ii > 7) bb |= (1 << WDP3);
+
+  uint8_t oldSREG = SREG;
+  cli();
+
+  wdt_reset();
+  MCUSR &= ~(1 << WDRF);
+
+  // Timed sequence: enable configuration change, then set interrupt-only WDT.
+  WDTCR |= (1 << WDCE) | (1 << WDE);
+  WDTCR = bb | (1 << WDIE);
+
+  SREG = oldSREG;
+}
+
+ISR(WDT_vect)
+{
+  f_wdt = true;
+}
+
+// ===========================================================================
+// 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 LED junction capacitance.
+  pinMode(LED_N, OUTPUT);
+  pinMode(LED_P, OUTPUT);
+  digitalWrite(LED_N, HIGH);
+  digitalWrite(LED_P, LOW);
+
+  // Let the N-side float and measure bleed-down time.
+  pinMode(LED_N, INPUT);
+  digitalWrite(LED_N, LOW);   // disable internal pullup
+
+  for (i = 0; i < 30000; i++) {
+    if (digitalRead(LED_N) == LOW) break;
+  }
+
+  // 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;
+}
+
+// ===========================================================================
+// 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);
+  digitalWrite(LED_P, LOW);
+
+  const size_t len = strlen_P(morseText);
+
+  for (size_t i = 0; i < len; i++) {
+    char c = (char)pgm_read_byte(&morseText[i]);
+
+    // Allow lowercase source text without silently breaking timing.
+    if (c >= 'a' && c <= 'z') {
+      c = c - 'a' + 'A';
+    }
+
+    bool symbolSent = false;
+
+    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/ATTINY45_2014_MorseThrowie/ATTINY45_2014_MorseThrowie.ino

@@ -183,8 +183,8 @@
 // theoretical you can use up to 3 LED. For example you can use it for a
 // landmark beacon. So if you point this LEDs to different directions you can 
 // detect the position in dependence of your location to the bacon. 
-#define LED1_N_SIDE 4
+#define LED1_N_SIDE 3 
-#define LED1_P_SIDE 3
+#define LED1_P_SIDE 4
 
 // ===========================================================================
 // Variables

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);
+    }
+  }
+}

hardware/0001_FireFly-Solar/0001_FireFly-Solar.kicad_dru

@@ -0,0 +1,5 @@
+(version 1)
+(rule Minimum_text_height_and_thickness_1
+	(constraint text_height (min 0.6mm))
+	(constraint text_thickness (min 0.1mm))
+)

hardware/0001_FireFly-Solar/0001_FireFly-Solar.kicad_prl

@@ -1,6 +1,6 @@
 {
   "board": {
-    "active_layer": 25,
+    "active_layer": 5,
     "active_layer_preset": "",
     "auto_track_width": true,
     "hidden_netclasses": [],

hardware/0001_FireFly-Solar/0001_FireFly-Solar.kicad_pro

@@ -1,6 +1,349 @@
 {
   "board": {
     "3dviewports": [],
+    "design_settings": {
+      "defaults": {
+        "apply_defaults_to_fp_barcodes": false,
+        "apply_defaults_to_fp_dimensions": false,
+        "apply_defaults_to_fp_fields": false,
+        "apply_defaults_to_fp_shapes": false,
+        "apply_defaults_to_fp_text": false,
+        "board_outline_line_width": 0.05,
+        "copper_line_width": 0.2,
+        "copper_text_italic": false,
+        "copper_text_size_h": 1.5,
+        "copper_text_size_v": 1.5,
+        "copper_text_thickness": 0.3,
+        "copper_text_upright": false,
+        "courtyard_line_width": 0.05,
+        "dimension_precision": 4,
+        "dimension_units": 3,
+        "dimensions": {
+          "arrow_length": 1270000,
+          "extension_offset": 500000,
+          "keep_text_aligned": true,
+          "suppress_zeroes": true,
+          "text_position": 0,
+          "units_format": 0
+        },
+        "fab_line_width": 0.1,
+        "fab_text_italic": false,
+        "fab_text_size_h": 1.0,
+        "fab_text_size_v": 1.0,
+        "fab_text_thickness": 0.15,
+        "fab_text_upright": false,
+        "other_line_width": 0.1,
+        "other_text_italic": false,
+        "other_text_size_h": 1.0,
+        "other_text_size_v": 1.0,
+        "other_text_thickness": 0.15,
+        "other_text_upright": false,
+        "pads": {
+          "drill": 0.7,
+          "height": 1.4,
+          "width": 1.4
+        },
+        "silk_line_width": 0.1,
+        "silk_text_italic": false,
+        "silk_text_size_h": 1.0,
+        "silk_text_size_v": 1.0,
+        "silk_text_thickness": 0.1,
+        "silk_text_upright": false,
+        "zones": {
+          "border_display_style": 2,
+          "border_hatch_pitch": 0.5,
+          "corner_radius": 0.0,
+          "corner_smoothing": 0,
+          "fill_mode": 0,
+          "hatch_gap": 1.5,
+          "hatch_orientation": 0.0,
+          "hatch_smoothing_level": 0,
+          "hatch_smoothing_value": 0.1,
+          "hatch_thickness": 1.0,
+          "min_clearance": 0.5,
+          "min_island_area": 10.0,
+          "min_thickness": 0.25,
+          "pad_connection": 1,
+          "remove_islands": 0,
+          "thermal_relief_gap": 0.5,
+          "thermal_relief_spoke_width": 0.5
+        }
+      },
+      "diff_pair_dimensions": [
+        {
+          "gap": 0.0,
+          "via_gap": 0.0,
+          "width": 0.0
+        }
+      ],
+      "drc_exclusions": [
+        [
+          "copper_edge_clearance|131952996|49276030|d5a8d279-1277-4128-8111-479753d97832|74ba0eb0-a42b-49db-8990-e7e337244d89",
+          ""
+        ],
+        [
+          "copper_edge_clearance|135254996|49276021|d5a8d279-1277-4128-8111-479753d97832|6760cf2b-9d51-44e9-8541-9b08cc6bed3a",
+          ""
+        ],
+        [
+          "copper_edge_clearance|138556996|49276011|d5a8d279-1277-4128-8111-479753d97832|5b16be99-1a09-4cc0-a4d6-0e5fae921e96",
+          ""
+        ],
+        [
+          "text_height|141224000|109999000|18cc7c24-1e1e-47b4-bd81-2abaec8c3831|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|129032000|119126000|be078bc2-b3be-4c33-abfe-930461332b78|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|129032000|122936000|57275588-b94d-44a7-b263-ab2e942abbb9|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|129032000|126746000|ac73bb6c-6b4c-4683-bc6b-c539afa6834f|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|129032000|130556000|dfc1c2d5-221c-45bf-8f4f-92d8a3ddf04a|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|129032000|134366000|e9026731-8c2e-491a-9b73-4cda2fa80a02|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|129032000|138176000|cf4eeb69-e06f-463f-be45-22626ac2c2b4|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|129032000|141986000|c29774df-bdb9-44e2-a17d-cfa3cd693d71|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|129184400|150241000|88401ad0-1dea-4344-ab33-329fd06bd493|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|135148000|106152000|7c4ccd6a-1b52-4734-bd95-092ada163852|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|135382000|84709000|88b0a397-e4a2-4145-86f6-0fa60b4a4bd9|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|141224000|109999000|18cc7c24-1e1e-47b4-bd81-2abaec8c3831|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|141325600|150144800|5da7a07f-f063-43b3-a149-e672965b459b|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|141478000|119126000|40b0fefb-8b86-43f7-b24d-e20c4677b223|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|141478000|122936000|77ee43fb-9700-42ab-8702-560042b5edd3|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|141478000|126746000|833d2a60-9010-4cb2-8045-b8050c8ee771|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|141478000|130556000|5a756363-e24d-4c12-82cf-59fc84a986ae|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|141478000|134366000|685c5797-de13-4bd0-a3b9-5fb75b4b9dad|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|141478000|138176000|15931c23-e5f6-4be3-ba3e-7a720c730e9b|00000000-0000-0000-0000-000000000000",
+          ""
+        ],
+        [
+          "text_thickness|141478000|141986000|e240b788-8dbb-43c9-8c9f-717e069201be|00000000-0000-0000-0000-000000000000",
+          ""
+        ]
+      ],
+      "meta": {
+        "version": 2
+      },
+      "rule_severities": {
+        "annular_width": "error",
+        "clearance": "error",
+        "connection_width": "warning",
+        "copper_edge_clearance": "error",
+        "copper_sliver": "warning",
+        "courtyards_overlap": "error",
+        "creepage": "error",
+        "diff_pair_gap_out_of_range": "error",
+        "diff_pair_uncoupled_length_too_long": "error",
+        "drill_out_of_range": "error",
+        "duplicate_footprints": "warning",
+        "extra_footprint": "warning",
+        "footprint": "error",
+        "footprint_filters_mismatch": "ignore",
+        "footprint_symbol_field_mismatch": "warning",
+        "footprint_symbol_mismatch": "warning",
+        "footprint_type_mismatch": "ignore",
+        "hole_clearance": "error",
+        "hole_to_hole": "warning",
+        "holes_co_located": "warning",
+        "invalid_outline": "error",
+        "isolated_copper": "warning",
+        "item_on_disabled_layer": "error",
+        "items_not_allowed": "error",
+        "length_out_of_range": "error",
+        "lib_footprint_issues": "warning",
+        "lib_footprint_mismatch": "warning",
+        "malformed_courtyard": "error",
+        "microvia_drill_out_of_range": "error",
+        "mirrored_text_on_front_layer": "warning",
+        "missing_courtyard": "ignore",
+        "missing_footprint": "warning",
+        "missing_tuning_profile": "warning",
+        "net_conflict": "warning",
+        "nonmirrored_text_on_back_layer": "warning",
+        "npth_inside_courtyard": "error",
+        "padstack": "warning",
+        "pth_inside_courtyard": "error",
+        "shorting_items": "error",
+        "silk_edge_clearance": "ignore",
+        "silk_over_copper": "warning",
+        "silk_overlap": "ignore",
+        "skew_out_of_range": "error",
+        "solder_mask_bridge": "error",
+        "starved_thermal": "ignore",
+        "text_height": "warning",
+        "text_on_edge_cuts": "error",
+        "text_thickness": "warning",
+        "through_hole_pad_without_hole": "error",
+        "too_many_vias": "error",
+        "track_angle": "error",
+        "track_dangling": "warning",
+        "track_not_centered_on_via": "ignore",
+        "track_on_post_machined_layer": "error",
+        "track_segment_length": "error",
+        "track_width": "error",
+        "tracks_crossing": "error",
+        "tuning_profile_track_geometries": "ignore",
+        "unconnected_items": "error",
+        "unresolved_variable": "error",
+        "via_dangling": "warning",
+        "zones_intersect": "error"
+      },
+      "rules": {
+        "max_error": 0.005,
+        "min_clearance": 0.0,
+        "min_connection": 0.0,
+        "min_copper_edge_clearance": 0.5,
+        "min_groove_width": 0.0,
+        "min_hole_clearance": 0.25,
+        "min_hole_to_hole": 0.25,
+        "min_microvia_diameter": 0.2,
+        "min_microvia_drill": 0.1,
+        "min_resolved_spokes": 2,
+        "min_silk_clearance": 0.0,
+        "min_text_height": 0.8,
+        "min_text_thickness": 0.08,
+        "min_through_hole_diameter": 0.3,
+        "min_track_width": 0.2,
+        "min_via_annular_width": 0.1,
+        "min_via_diameter": 0.5,
+        "solder_mask_to_copper_clearance": 0.0,
+        "use_height_for_length_calcs": true
+      },
+      "teardrop_options": [
+        {
+          "td_onpthpad": true,
+          "td_onroundshapesonly": false,
+          "td_onsmdpad": true,
+          "td_ontrackend": false,
+          "td_onvia": true
+        }
+      ],
+      "teardrop_parameters": [
+        {
+          "td_allow_use_two_tracks": true,
+          "td_curve_segcount": 0,
+          "td_height_ratio": 1.0,
+          "td_length_ratio": 0.5,
+          "td_maxheight": 2.0,
+          "td_maxlen": 1.0,
+          "td_on_pad_in_zone": false,
+          "td_target_name": "td_round_shape",
+          "td_width_to_size_filter_ratio": 0.9
+        },
+        {
+          "td_allow_use_two_tracks": true,
+          "td_curve_segcount": 0,
+          "td_height_ratio": 1.0,
+          "td_length_ratio": 0.5,
+          "td_maxheight": 2.0,
+          "td_maxlen": 1.0,
+          "td_on_pad_in_zone": false,
+          "td_target_name": "td_rect_shape",
+          "td_width_to_size_filter_ratio": 0.9
+        },
+        {
+          "td_allow_use_two_tracks": true,
+          "td_curve_segcount": 0,
+          "td_height_ratio": 1.0,
+          "td_length_ratio": 0.5,
+          "td_maxheight": 2.0,
+          "td_maxlen": 1.0,
+          "td_on_pad_in_zone": false,
+          "td_target_name": "td_track_end",
+          "td_width_to_size_filter_ratio": 0.9
+        }
+      ],
+      "track_widths": [
+        0.0,
+        0.127,
+        0.254,
+        0.508,
+        0.635,
+        1.27
+      ],
+      "tuning_pattern_settings": {
+        "diff_pair_defaults": {
+          "corner_radius_percentage": 80,
+          "corner_style": 1,
+          "max_amplitude": 1.0,
+          "min_amplitude": 0.2,
+          "single_sided": false,
+          "spacing": 1.0
+        },
+        "diff_pair_skew_defaults": {
+          "corner_radius_percentage": 80,
+          "corner_style": 1,
+          "max_amplitude": 1.0,
+          "min_amplitude": 0.2,
+          "single_sided": false,
+          "spacing": 0.6
+        },
+        "single_track_defaults": {
+          "corner_radius_percentage": 80,
+          "corner_style": 1,
+          "max_amplitude": 1.0,
+          "min_amplitude": 0.2,
+          "single_sided": false,
+          "spacing": 0.6
+        }
+      },
+      "via_dimensions": [
+        {
+          "diameter": 0.0,
+          "drill": 0.0
+        }
+      ],
+      "zones_allow_external_fillets": false
+    },
     "ipc2581": {
       "bom_rev": "",
       "dist": "",
@@ -8,7 +351,7 @@
       "internal_id": "",
       "mfg": "",
       "mpn": "",
-      "sch_revision": "0"
+      "sch_revision": "1"
     },
     "layer_pairs": [],
     "layer_presets": [],
@@ -416,7 +759,7 @@
         "uuid": "d6486f66-f0ec-4484-bce4-0ec6b0e57e1d"
       }
     ],
-    "used_designators": "#FLG1-2,R2-3,J4,#PWR3-6,D5-6,C2-6,L1,U1-2",
+    "used_designators": "J1-2",
     "variants": []
   },
   "sheets": [

hardware/3D_Print-Designs/FireFly3DMechanical_v0.1.scad

@@ -1,288 +0,0 @@
-/*
-    FireFly tetrahedron adapter
-    Base STL: tetrahedron40mmC.stl
-
-    Purpose:
-    - Import original 40 mm foldable tetrahedron STL
-    - Scale it to 60 mm base geometry
-    - Add cable holes, vent/drain holes, and optional PCB mounting holes
-
-    Workflow:
-    1. Set PART = "upper"
-    2. Render with F6
-    3. Export STL
-    4. Set PART = "lower"
-    5. Render with F6
-    6. Export STL
-
-    Notes:
-    - Hole coordinates are defined on the original 40 mm STL coordinate system.
-    - The script scales them automatically to 60 mm.
-    - First export should be treated as v0.1 prototype.
-*/
-
-
-/* =========================
-   Main selection
-   ========================= */
-
-PART = "upper";          // "upper", "lower", or "both_preview"
-
-
-/* =========================
-   Input file
-   ========================= */
-
-input_stl = "tetrahedron40mmC.stl";
-
-
-/* =========================
-   Scaling
-   ========================= */
-
-// Original tetrahedron edge length
-original_edge_mm = 40;
-
-// Target mechanical base size
-target_edge_mm = 60;
-
-// XY scale from 40 mm to 60 mm
-scale_xy = target_edge_mm / original_edge_mm;   // 1.5
-
-// Keep original thickness.
-// Set to 1.2 or 1.3 if you want a slightly thicker part.
-scale_z = 1.0;
-
-
-/* =========================
-   General hole settings
-   ========================= */
-
-hole_fn = 40;
-cut_height = 20;
-
-
-/* =========================
-   Feature switches
-   ========================= */
-
-add_upper_cable_holes = true;
-add_upper_hanger_hole = true;
-
-add_lower_vent_holes = true;
-add_lower_cable_holes = true;
-add_lower_pcb_mount_holes = true;
-
-// Keep this false for the first prototype.
-// Standoffs may interfere with folding depending on print orientation.
-add_lower_pcb_standoffs = false;
-
-
-/* =========================
-   Hole sizes
-   ========================= */
-
-cable_hole_d = 3.2;          // for small solar-panel wires
-hanger_hole_d = 3.5;         // for small ring / wire / eyelet
-vent_hole_d = 2.0;           // condensation vent / drain holes
-pcb_screw_hole_d = 2.2;      // M2 clearance-ish
-pcb_standoff_d = 6.0;
-pcb_standoff_h = 3.0;
-
-
-/* =========================
-   Coordinate reference
-   =========================
-
-   The uploaded STL is approximately:
-
-   X: -34.64 to +34.64
-   Y: -20.00 to +60.00
-   Z:  -0.10 to  +2.00
-
-   The original model is a flat foldable tetrahedron net.
-   Coordinates below are before scaling.
-*/
-
-
-/* =========================
-   Upper part hole positions
-   ========================= */
-
-// Cable holes for three solar panels.
-// Adjust after checking where your real panel wires exit.
-upper_cable_points = [
-    [-18, 20],
-    [ 24,  7],
-    [ 24, 33]
-];
-
-// Optional hanger hole close to one upper fold/vertex area.
-// If this weakens the corner too much, disable it and use an external loop instead.
-upper_hanger_points = [
-    [0, 38]
-];
-
-
-/* =========================
-   Lower part hole positions
-   ========================= */
-
-// Cable transfer holes between upper solar section and lower electronics bay.
-lower_cable_points = [
-    [-10, 20],
-    [ 12, 13],
-    [ 12, 27]
-];
-
-// Small vent/drain hole clusters near likely lower/edge areas.
-// These are deliberately small.
-lower_vent_centres = [
-    [  0,  3],
-    [  0, 37],
-    [-30, 20],
-    [ 31, 20]
-];
-
-// Approximate triangular PCB mounting pattern.
-// Tune this after measuring your actual red triangle PCB.
-lower_pcb_mount_points = [
-    [  0,  8],
-    [ 25, 20],
-    [  0, 32]
-];
-
-
-/* =========================
-   Basic modules
-   ========================= */
-
-module base_import_scaled()
-{
-    scale([scale_xy, scale_xy, scale_z])
-        import(input_stl, convexity = 10);
-}
-
-
-module vertical_hole(p, d)
-{
-    translate([p[0] * scale_xy, p[1] * scale_xy, 1])
-        cylinder(h = cut_height, d = d, center = true, $fn = hole_fn);
-}
-
-
-module vent_cluster(p)
-{
-    // Small 2 x 3 vent/drain pattern.
-    // Pitch is in final millimetres, not original model coordinates.
-    pitch = 3.0;
-
-    for (ix = [-1, 0, 1])
-        for (iy = [0, 1])
-            translate([
-                p[0] * scale_xy + ix * pitch,
-                p[1] * scale_xy + iy * pitch,
-                1
-            ])
-                cylinder(h = cut_height, d = vent_hole_d, center = true, $fn = hole_fn);
-}
-
-
-module pcb_standoff(p)
-{
-    // Standoff added on top of the flat STL.
-    // Use only if you confirm it does not block folding.
-    translate([p[0] * scale_xy, p[1] * scale_xy, 2.1 * scale_z])
-        cylinder(h = pcb_standoff_h, d = pcb_standoff_d, center = false, $fn = hole_fn);
-}
-
-
-/* =========================
-   Upper tetrahedron
-   ========================= */
-
-module upper_part()
-{
-    difference()
-    {
-        base_import_scaled();
-
-        if (add_upper_cable_holes)
-        {
-            for (p = upper_cable_points)
-                vertical_hole(p, cable_hole_d);
-        }
-
-        if (add_upper_hanger_hole)
-        {
-            for (p = upper_hanger_points)
-                vertical_hole(p, hanger_hole_d);
-        }
-    }
-}
-
-
-/* =========================
-   Lower tetrahedron
-   ========================= */
-
-module lower_part()
-{
-    difference()
-    {
-        union()
-        {
-            base_import_scaled();
-
-            if (add_lower_pcb_standoffs)
-            {
-                for (p = lower_pcb_mount_points)
-                    pcb_standoff(p);
-            }
-        }
-
-        if (add_lower_cable_holes)
-        {
-            for (p = lower_cable_points)
-                vertical_hole(p, cable_hole_d);
-        }
-
-        if (add_lower_vent_holes)
-        {
-            for (p = lower_vent_centres)
-                vent_cluster(p);
-        }
-
-        if (add_lower_pcb_mount_holes)
-        {
-            for (p = lower_pcb_mount_points)
-                vertical_hole(p, pcb_screw_hole_d);
-        }
-    }
-}
-
-
-/* =========================
-   Output
-   ========================= */
-
-if (PART == "upper")
-{
-    upper_part();
-}
-else if (PART == "lower")
-{
-    lower_part();
-}
-else if (PART == "both_preview")
-{
-    translate([-80, 0, 0])
-        upper_part();
-
-    translate([80, 0, 0])
-        lower_part();
-}
-else
-{
-    echo("Invalid PART setting. Use upper, lower, or both_preview.");
-}