try to use timer interrupt

.gitignore

@@ -257,3 +257,5 @@ cython_debug/
 .pypirc
 
 pyupdi-env/
+
+sbom.spdx.json

CMakeLists.txt

@@ -1,37 +1,79 @@
 cmake_minimum_required(VERSION 3.13)
-
-# Project
 project(lezyne-rear-light-firmware C)
 
 # MCU and clock
 set(MCU attiny202)
-set(F_CPU 5000000UL) # 5 MHz
+set(F_CPU 5000000UL)
 
-# Toolchain executables
+# Toolchain
 set(CMAKE_SYSTEM_NAME Generic)
 set(CMAKE_C_COMPILER avr-gcc)
 set(OBJCOPY avr-objcopy)
 
-# Compiler flags: optimize, warnings, treat warnings as errors
-set(CMAKE_C_FLAGS "-mmcu=${MCU} -DF_CPU=${F_CPU} -Os -Wall -Werror")
-
 # Sources
 add_executable(main.elf main.c)
 
-# HEX file
-add_custom_command(
-    OUTPUT main.hex
+# Compiler and linker flags
+target_compile_options(main.elf PRIVATE -mmcu=${MCU} -DF_CPU=${F_CPU} -Os -Wall -Werror)
+set_target_properties(main.elf PROPERTIES LINK_FLAGS "-mmcu=${MCU}")
+
+# Create HEX and BIN after build
+add_custom_command(TARGET main.elf POST_BUILD
     COMMAND ${OBJCOPY} -O ihex -R .eeprom main.elf main.hex
-    DEPENDS main.elf
-)
-
-# BIN file
-add_custom_command(
-    OUTPUT main.bin
     COMMAND ${OBJCOPY} -O binary -R .eeprom main.elf main.bin
-    DEPENDS main.elf
 )
 
-# Targets
-add_custom_target(hex ALL DEPENDS main.hex)
-add_custom_target(bin ALL DEPENDS main.bin)
+# Optional: show size
+find_program(SIZE_TOOL avr-size)
+if(SIZE_TOOL)
+    add_custom_command(TARGET main.elf POST_BUILD
+        COMMAND ${SIZE_TOOL} --mcu=${MCU} --format=avr main.elf
+    )
+endif()
+
+# Flash target using pymcuprog
+find_program(PYMCUPROG pymcuprog)
+set(UPDI_PORT "/dev/ttyUSB0" CACHE STRING "Serial port for UPDI programming")
+
+if(PYMCUPROG)
+    add_custom_target(flash
+        COMMAND ${PYMCUPROG} -t uart -u ${UPDI_PORT} -d ${MCU} write -f main.hex
+        DEPENDS main.hex
+        COMMENT "Flashing ${MCU} with pymcuprog..."
+    )
+else()
+    message(WARNING "pymcuprog not found in PATH. 'make flash' will not be available.")
+endif()
+
+# --- SBOM Generation (SPDX JSON) ---
+find_package(Git REQUIRED)
+
+# Generate current timestamp in ISO 8601 format (UTC)
+string(TIMESTAMP CMAKE_TIMESTAMP "%Y-%m-%dT%H:%M:%SZ" UTC)
+
+# Get current git hash
+execute_process(
+    COMMAND ${GIT_EXECUTABLE} rev-parse HEAD
+    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+    OUTPUT_VARIABLE GIT_HASH
+    OUTPUT_STRIP_TRAILING_WHITESPACE
+)
+
+# Get avr-gcc version
+execute_process(
+    COMMAND ${CMAKE_C_COMPILER} --version
+    OUTPUT_VARIABLE AVR_GCC_VERSION
+    OUTPUT_STRIP_TRAILING_WHITESPACE
+)
+
+# Where to write SBOM
+set(SBOM_FILE ${CMAKE_SOURCE_DIR}/sbom.spdx.json)
+
+# Generate from template
+configure_file(${CMAKE_SOURCE_DIR}/sbom.template.json ${SBOM_FILE} @ONLY)
+
+# Always regenerate on build
+add_custom_target(sbom ALL
+    DEPENDS ${SBOM_FILE}
+    COMMENT "Generating SPDX SBOM..."
+)

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2025 localhorst
+Copyright (c) 2025 Hendrik Schutter
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and 
 associated documentation files (the "Software"), to deal in the Software without restriction, including 

README.md

@@ -2,6 +2,8 @@
 
 **🚧 Work in progress. No complete firmware yet 🚧**
 
+🚀 For pre-build binaries go to [Releases](https://git.mosad.xyz/localhorst/lezyne-rear-light-firmware/releases).
+
 Open firmware for Lezyne bike rear lights based on ATTINY202
 
 This repository contains a minimal firmware as a **C project** for the ATtiny202 microcontroller using **GCC**, **CMake**, and **VS Code**. It also includes instructions for programming the chip using an **FT232 USB-UART adapter** via the UPDI interface with `pymcuprog`.  
@@ -105,11 +107,11 @@ Hardware: FT232 USB-UART adapter connected to UPDI with a 4.7 kΩ resistor.
 
 | Signal | PCB Usage         | LOW                      | HIGH                      |
 |--------|-------------------|--------------------------|---------------------------|
-| PA6    | Green LED         | LED **ON**               | LED OFF                   |
-| PA7    | Red LED           | LED **ON**               | LED OFF                   |
-| PA1    | LED 1–2           | LED(s) **ON**            | LED(s) OFF                |
-| PA2    | LED 3–6           | LED(s) **ON**            | LED(s) OFF                |
-| PA3    | LED 7–8           | LED(s) **ON**            | LED(s) OFF                |
+| PA6    | Green LED         | LED **ON**               | LED **OFF**               |
+| PA7    | Red LED           | LED **ON**               | LED **OFF**               |
+| PA1    | LED 1–2           | LED(s) **OFF**           | LED(s) **ON**             |
+| PA2    | LED 3–6           | LED(s) **OFF**           | LED(s) **ON**             |
+| PA3    | LED 7–8           | LED(s) **OFF**           | LED(s) **ON**             |
 | PA0    | Activation Button | Button **pressed** (GND) | Button released (pull-up) |
 
 ## License

main.c

@@ -1,70 +1,82 @@
 /**
  * @file main.c
- * @brief Bike rear light implementation for ATTINY202.
- *
+ * @brief Bike rear light implementation for ATTINY202 with low-power standby.
  */
 
 #include <stdint.h>
 #include <stdbool.h>
 #include <avr/io.h>
 #include <util/delay.h>
+#include <avr/sleep.h>
+#include <avr/interrupt.h>
 
-/** @defgroup LED_Masks LED bitmasks for PORTA
- *  @{
- */
 #define BUTTON_PIN_MASK 0x01 // PA0
-#define PA1_SET_MASK 0x02    ///< LED 1–2
-#define PA2_SET_MASK 0x04    ///< LED 3–6
-#define PA3_SET_MASK 0x08    ///< LED 7–8
-#define PA6_SET_MASK 0x40    ///< Green LED pin
-#define PA7_SET_MASK 0x80    ///< Red LED
-/** @} */
+#define PA1_SET_MASK 0x02    // LED 1–2
+#define PA2_SET_MASK 0x04    // LED 3–6
+#define PA3_SET_MASK 0x08    // LED 7–8
+#define PA6_SET_MASK 0x40    // Green LED
+#define PA7_SET_MASK 0x80    // Red LED
 
-#define MAIN_LOOP_SLEEP 10U                 // Main loop delay in ms (system tick)
-#define BUTTON_LONG_PRESS_DURATION_MS 1000U // Long press detection threshold
-#define BUTTON_IGNORE_DURATION_MS 1000U     // Time that the button is ignored after a long press
+#define MAIN_LOOP_SLEEP 50U                 // Loop period in ms
+#define BUTTON_LONG_PRESS_DURATION_MS 1000U // Long press threshold
+#define BUTTON_IGNORE_DURATION_MS 1000U     // Ignore after long press
 
-/** @brief Convert milliseconds to system ticks (integer division). */
 #define MS_TO_TICKS(ms) ((ms) / MAIN_LOOP_SLEEP)
 
-/** @brief Global flags */
-volatile bool bLedEnabled = true;
+volatile bool bLedEnabled = false;
 volatile bool bBtnPressed = false;
 
-// Function forward declarations
-void blinkLed(bool resetCounters);
 static inline void leds_off(void);
 static inline void leds_on(void);
+static void battery_level_indicator(void);
 static void handleSwitch(void);
+void blinkLed(bool resetCounters);
 
-/**
- * @brief Main entry point.
- *
- * Initializes I/O ports and runs the main loop, periodically calling @ref blinkLed().
- *
- * @return never returns
- */
+/* --- Timer init: Use RTC PIT for periodic wake-up --- */
+void init_timer(void)
+{
+    RTC.CLKSEL = RTC_CLKSEL_INT1K_gc; // 1 kHz ULP clock for RTC
+    while (RTC.STATUS > 0)
+    {
+    } // Wait for sync
+
+    RTC.PITINTCTRL = RTC_PI_bm;        // Enable PIT interrupt
+    RTC.PITCTRLA = RTC_PERIOD_CYC64_gc // ≈64 ms wake-up (~50 ms)
+                   | RTC_PITEN_bm;     // Enable PIT
+}
+
+ISR(RTC_PIT_vect)
+{
+    RTC.PITINTFLAGS = RTC_PI_bm; // Clear interrupt flag
+}
+
+/* --- MAIN --- */
 int main(void)
 {
-    // --- configure LED pins as outputs ---
-    VPORTA.DIR = (PA1_SET_MASK | PA2_SET_MASK | PA3_SET_MASK |
-                  /*PA6_SET_MASK |*/ // PA6 now input (switch)
-                  PA7_SET_MASK);
+    // Configure LED pins as outputs
+    VPORTA.DIR = (PA1_SET_MASK | PA2_SET_MASK | PA3_SET_MASK | PA6_SET_MASK | PA7_SET_MASK);
 
     // Configure PA0 as input with pull-up
     VPORTA.DIR &= ~BUTTON_PIN_MASK;    // Input
     PORTA.PIN0CTRL = PORT_PULLUPEN_bm; // Pull-up enabled
 
-    // --- ensure all LEDs off at startup ---
+    // Ensure all LEDs off at startup
     leds_off();
-    VPORTA.OUT &= (uint8_t) ~(PA7_SET_MASK);
+    battery_level_indicator(); // TODO: Implement
 
     bool bLedEnabledOld = bLedEnabled;
 
-    while (true)
-    {
-        handleSwitch(); // check switch state
+    cli();
+    init_timer();
+    sei();
 
+    set_sleep_mode(SLEEP_MODE_STANDBY);
+
+    while (1)
+    {
+        handleSwitch(); // Check switch state
+
+        // Light LEDs while button is pressed
         if (bBtnPressed)
         {
             leds_on();
@@ -74,34 +86,36 @@ int main(void)
             leds_off();
         }
 
+        // Long press detected → show confirmation blink
         if (bLedEnabledOld != bLedEnabled)
         {
-            // A long press detected --> confirm with a blink
             bLedEnabledOld = bLedEnabled;
+
             leds_off();
             _delay_ms(BUTTON_IGNORE_DURATION_MS / 10);
             leds_on();
             _delay_ms(BUTTON_IGNORE_DURATION_MS / 10);
             leds_off();
             _delay_ms(BUTTON_IGNORE_DURATION_MS);
-            blinkLed(true); // reset the persistent counters
+
+            blinkLed(true); // reset blink state machine
         }
         else
         {
-            if ((bLedEnabled) && (!bBtnPressed))
+            if (bLedEnabled && !bBtnPressed)
             {
-                blinkLed(false);
+                blinkLed(false); // run normal blink
             }
         }
 
-        _delay_ms(MAIN_LOOP_SLEEP);
+        sleep_enable();
+        sleep_cpu(); // Sleep until PIT wakes
+        sleep_disable();
     }
 }
 
 /**
- * @brief Switch off all controlled LEDs (PA1, PA2, PA3).
- *
- * @note Declared inline for speed (single instruction sequence).
+ * @brief Turn off all controlled LEDs (PA1, PA2, PA3)
  */
 static inline void leds_off(void)
 {
@@ -109,9 +123,7 @@ static inline void leds_off(void)
 }
 
 /**
- * @brief Switch on all controlled LEDs (PA1, PA2, PA3).
- *
- * @note Declared inline for speed (single instruction sequence).
+ * @brief Turn on all controlled LEDs (PA1, PA2, PA3)
  */
 static inline void leds_on(void)
 {
@@ -119,26 +131,31 @@ static inline void leds_on(void)
 }
 
 /**
- * @brief Handle momentary switch input on PA6. TODO: Switch to PA0
+ * @brief Battery monitoring
+ */
+static void battery_level_indicator(void)
+{
+    // TODO: Implement
+    VPORTA.OUT |= (PA6_SET_MASK | PA7_SET_MASK); // green + red OFF
+}
+
+/**
+ * @brief Handle momentary switch input on PA0
  *
- * A press longer than 2 seconds toggles ::bLedEnabled.
- * Uses simple state and counters for debouncing and long-press detection.
+ * A long press toggles ::bLedEnabled.
  */
 static void handleSwitch(void)
 {
-    static uint16_t pressTicks = 0;  ///< press duration counter
-    static bool prevPressed = false; ///< previous switch state
+    static uint16_t pressTicks = 0;  ///< Press duration counter
+    static bool prevPressed = false; ///< Previous button state
 
-    bool pressed = !(VPORTA.IN & BUTTON_PIN_MASK); // active-low
+    bool pressed = !(VPORTA.IN & BUTTON_PIN_MASK); // Active-low
 
     if (pressed)
     {
         bBtnPressed = true;
         if (pressTicks < 0xFFFF)
-        {
-            // prevent overflow
-            pressTicks++;
-        }
+            pressTicks++; // Prevent overflow
     }
     else
     {
@@ -148,15 +165,14 @@ static void handleSwitch(void)
 
     if (prevPressed && pressTicks >= MS_TO_TICKS(BUTTON_LONG_PRESS_DURATION_MS))
     {
-        // long press detected → toggle blinking
-        bLedEnabled = !bLedEnabled;
+        bLedEnabled = !bLedEnabled; // Toggle LED blinking
     }
 
     prevPressed = pressed;
 }
 
 /**
- * @brief LED blink state machine (bike rear light style).
+ * @brief LED blink state machine (bike rear light style)
  *
  * Normal cycle:
  *   0: all off, wait 250 ms
@@ -172,15 +188,13 @@ static void handleSwitch(void)
  */
 void blinkLed(bool resetCounters)
 {
-    // --- precomputed constants ---
-    const uint8_t T50 = MS_TO_TICKS(50);   ///< 50 ms in ticks
-    const uint8_t T100 = MS_TO_TICKS(100); ///< 100 ms in ticks
-    const uint8_t T250 = MS_TO_TICKS(250); ///< 250 ms in ticks
+    const uint8_t T50 = MS_TO_TICKS(50);
+    const uint8_t T100 = MS_TO_TICKS(100);
+    const uint8_t T250 = MS_TO_TICKS(250);
 
-    // --- persistent state ---
-    static uint16_t counter = 0; ///< ticks for current state
-    static uint8_t state = 2;    ///< start with first LEDs-on state
-    static uint8_t cycle = 0;    ///< cycle counter
+    static uint16_t counter = 0;
+    static uint8_t state = 2; // start with LEDs-on state
+    static uint8_t cycle = 0;
 
     if (resetCounters)
     {
@@ -287,7 +301,7 @@ void blinkLed(bool resetCounters)
         if (counter >= T250)
         {
             counter = 0;
-            state = 0; // restart normal sequence
+            state = 0;
         }
         break;
     }

sbom.template.json

@@ -0,0 +1,44 @@
+{
+    "spdxVersion": "SPDX-2.3",
+    "dataLicense": "CC0-1.0",
+    "SPDXID": "SPDXRef-DOCUMENT",
+    "name": "lezyne-rear-light-firmware",
+    "documentNamespace": "https://git.mosad.xyz/localhorst/lezyne-rear-light-firmware/@GIT_HASH@",
+    "creationInfo": {
+        "created": "@CMAKE_TIMESTAMP@",
+        "creators": [
+            "Tool: CMake+SPDX"
+        ]
+    },
+    "packages": [
+        {
+            "name": "main.c",
+            "SPDXID": "SPDXRef-mainc",
+            "downloadLocation": "https://git.mosad.xyz/localhorst/lezyne-rear-light-firmware/src/branch/main/main.c",
+            "filesAnalyzed": true,
+            "versionInfo": "@GIT_HASH@",
+            "licenseDeclared": "MIT License",
+            "homepage": "https://git.mosad.xyz/localhorst/lezyne-rear-light-firmware"
+        },
+        {
+            "name": "avr-gcc",
+            "SPDXID": "SPDXRef-avrgcc",
+            "downloadLocation": "NOASSERTION",
+            "filesAnalyzed": false,
+            "versionInfo": "@AVR_GCC_VERSION@",
+            "licenseDeclared": "GPL-3.0-or-later",
+            "supplier": "Organization: The GNU Project",
+            "homepage": "https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git"
+        },
+        {
+            "name": "avr-libc",
+            "SPDXID": "SPDXRef-avrlibc",
+            "downloadLocation": "NOASSERTION",
+            "filesAnalyzed": false,
+            "versionInfo": "2.2.1-1.2",
+            "licenseDeclared": "Modified BSD License",
+            "supplier": "Organization: AVRDUDES Authors",
+            "homepage": "https://github.com/avrdudes/avr-libc/"
+        }
+    ]
+}