fix message

README.md

@@ -2,7 +2,7 @@
 
 A simple voice recorder for Arduino using an SD card and an electret microphone amplifier circuit.
 
-Independent of any 3rd party libraries (unless delayed recording is used).
+Independent of any third-party libraries.
 
 ## Wiring (also documented in spybug/spybug.ino)
 ### SD Card Wiring
@@ -29,3 +29,9 @@ GND      |  GND
 Out      |  A0
 
 Out defaults to A0 (AdcChannel0), but can be set manually in `ADC_CHANNEL`.
+
+## Power Consumption (Arduino Nano)
+Mode      | Unmodified | No voltage regulator | No TTL module or voltage regulator
+----------|------------|----------------------|-----------------------------------
+Waiting   | ~10mA      | ~5.8mA               | ~6μA
+Recording | ~30mA      | ~25.1mA              | ~25mA

reset_sketch/reset_sketch.ino

@@ -0,0 +1,14 @@
+// Copyright 2022 Darwin Schuppan <darwin@nobrain.org>
+// SPDX license identifier: MIT
+
+#include "settings.hh"
+
+void setup() {
+	Serial.begin(9600);
+	Serial.print("Resetting EEPROM...");
+	EEPROM_Settings_Class settings;
+	settings.save();
+	Serial.println("done.");
+}
+
+void loop() {}

reset_sketch/settings.hh

@@ -0,0 +1 @@
+../spybug/settings.hh

spybug/aaa_config.hh

@@ -0,0 +1,31 @@
+// Copyright 2022 Darwin Schuppan <darwin@nobrain.org>
+// SPDX license identifier: MIT
+
+#pragma once
+
+/************************
+ BEGIN USER CONFIGURATION
+ ************************/
+//#define DEBUG_RECORDING
+
+#define PIN_COMPONENT_SWITCH 2 /* Use a digital signal to switch on/off the microphone and SD card for less power draw. */
+#define COMPONENT_SWITCH_ON HIGH
+
+#define SAMPLE_MODE_U8
+//#define SAMPLE_MODE_S16
+
+//#define ADC_PRESCALE_16 /* Up to ~60kHz. */
+//#define ADC_PRESCALE_32 /* Up to ~27kHz. */
+#define ADC_PRESCALE_64 /* Up to ~18kHz. */
+
+//#define U8_AMPLIFY_X2 /* (U8 sampling mode only) amplify audio by factor 2. */
+
+#define ADC_CHANNEL AdcChannel0
+#define TIMER_COMPARE 1000 /* 16MHz / 1000 = 16kHz. */
+#define FLUSH_SAMPLES 64000 /* Flush WAV file every n samples. */
+#define PIN_SS 10
+
+#define REC_FILE_FMT "REC_%03u.WAV" /* Must be all caps; must use %u in some form exactly once. */
+/**********************
+ END USER CONFIGURATION
+ **********************/

spybug/cmd.cpp

@@ -0,0 +1,191 @@
+// Copyright 2022 Darwin Schuppan <darwin@nobrain.org>
+// SPDX license identifier: MIT
+
+#include "cmd.hh"
+
+#include <Arduino.h>
+#include <SD.h>
+
+#include "aaa_config.hh"
+#include "fstr.hh"
+#include "io.hh"
+#include "settings.hh"
+#include "sys.hh"
+
+static bool sd_initialized = false;
+
+static void try_init_sd() {
+	if (sd_initialized)
+		return;
+	printf(F("Initializing SD card..."));
+	#ifdef PIN_COMPONENT_SWITCH
+		digitalWrite(PIN_COMPONENT_SWITCH, COMPONENT_SWITCH_ON);
+		delay(500); /* Wait for components to initialize. */
+	#endif
+	if (SD.begin(PIN_SS)) {
+		printf(F("Done.\n"));
+		sd_initialized = true;
+	} else
+		printf(F("\nError initializing SD card.\n"));
+}
+
+static void sd_error() {
+	printf(F("Error reading from SD card.\n"));
+	sd_initialized = false;
+}
+
+static void command_loop() {
+	// Process Commands
+	if (Serial.available()) {
+		char args[6][20];
+		size_t len = 0;
+		size_t n_args = 0;
+		int c = getchar();
+		while (c != '\n' && n_args < 4) {
+			if (c == ' ')
+				c = getchar();
+			else {
+				do {
+					args[n_args][len++] = c;
+					c = getchar();
+				} while (c != ' ' && c != '\n' && len < 20-1);
+				args[n_args][len] = 0;
+				len = 0;
+				n_args++;
+			}
+		}
+		if (n_args >= 1) {
+			if (fstreq(args[0], F("set"))) {
+				if ((n_args == 3 || n_args == 4) && fstreq(args[1], F("wait"))) {
+					float n = atof(args[2]);
+					unsigned long mins;
+					if (n_args == 4 && (fstreq(args[3], F("hours")) || fstreq(args[3], F("hour"))))
+						mins = 60.f * n;
+					else
+						mins = n;
+					settings.recording_delay = mins;
+					settings.save();
+					printf(F("Set waiting time to %lu minutes or "), settings.recording_delay);
+					print_special((float)settings.recording_delay / 60.f);
+					printf(F(" hours.\n"));
+				} else if (n_args == 3 && fstreq(args[1], F("serial"))) {
+					if (fstreq(args[2], F("on"))) {
+						settings.serial_log = true;
+						settings.save();
+						printf(F("Serial log enabled.\n"));
+					} else if (fstreq(args[2], F("off"))) {
+						settings.serial_log = false;
+						settings.save();
+						printf(F("Serial log disabled.\n"));
+					} else {
+						printf(F("Usage: 'set serial [on|off]'.\n"));
+					}
+				} else {
+					printf(F("Usage: 'set wait <number> [minutes|hours]' or 'set serial [on|off]'.\n"));
+				}
+			} else if (fstreq(args[0], F("get"))) {
+				if (n_args == 2 && fstreq(args[1], F("wait"))) {
+					printf(F("Current waiting time: %lu minutes or "), settings.recording_delay);
+					print_special((float)settings.recording_delay / 60.f);
+					printf(F(" hours.\n"));
+				} else {
+					printf(F("Usage: 'get wait'.\n"));
+				}
+			} else if (fstreq(args[0], F("sd"))) {
+				try_init_sd();
+				if (sd_initialized) {
+					if (n_args == 2 && fstreq(args[1], F("list"))) {
+						File root = SD.open("/");
+						if (root) {
+							printf(F("Files:\n"));
+							bool files = false;
+							size_t cols = 0;
+							while (1) {
+								File entry = root.openNextFile();
+								if (!entry)
+									break;
+								files = true;
+								if (cols >= 3) {
+									cols = 0;
+									printf(F("\n"));
+								}
+								printf(F("  %s"), entry.name());
+								cols++;
+								entry.close();
+							}
+							if (!files)
+								printf(F("[NONE]"));
+							printf(F("\n"));
+						} else
+							sd_error();
+						root.close();
+					} else if (n_args == 3 && fstreq(args[1], F("remove"))) {
+						if (SD.remove(args[2]))
+							printf(F("Deleted '%s'.\n"), args[2]);
+						else
+							printf(F("Error removing '%s'.\n"), args[2]);
+					} else if (n_args == 2 && fstreq(args[1], F("remove_all"))) {
+						File root = SD.open("/");
+						if (root) {
+							printf(F("Deleted:\n"));
+							bool deleted = false;
+							size_t cols = 0;
+							while (1) {
+								File entry = root.openNextFile();
+								if (!entry)
+									break;
+								const char *name = entry.name();
+								unsigned int garbage;
+								if (!entry.isDirectory() && sscanf(name, REC_FILE_FMT, &garbage) == 1) {
+									if (cols >= 3) {
+										cols = 0;
+										printf(F("\n"));
+									}
+									deleted = true;
+									SD.remove(name);
+									printf(F("  %s"), name);
+									cols++;
+								}
+								entry.close();
+							}
+							if (!deleted)
+								printf(F("[NONE]"));
+							printf(F("\n"));
+						} else
+							sd_error();
+						root.close();
+					} else if (n_args != 1) {
+						printf(F("Usage: 'sd list', 'sd remove <filename>' or 'sd remove_all'.\n"));
+					}
+				}
+			} else if (fstreq(args[0], F("help"))) {
+				printf(F("Commands:\n"));
+				printf(F("  help                               --  Display this page.\n"));
+				printf(F("  exit                               --  Leave command mode.\n"));
+				printf(F("  get wait                           --  Display current delay setting.\n"));
+				printf(F("  set wait <number> [minutes|hours]  --  Change current delay setting.\n"));
+				printf(F("  set serial [on|off]                --  Write log to serial output.\n"));
+				printf(F("  sd                                 --  Initialize the SD card.\n"));
+				printf(F("  sd list                            --  List file on SD card.\n"));
+				printf(F("  sd remove <filename>               --  Delete a file from SD card.\n"));
+				printf(F("  sd remove_all                      --  Delete all recordings from SD card.\n"));
+			} else if (fstreq(args[0], F("exit"))) {
+				printf(F("Bye!\n"));
+				Serial.flush();
+				full_reset();
+			} else
+				printf(F("Invalid command: '%s'. Type 'help' for a list of commands.\n"), args[0]);
+		} else {
+			printf(F("Please specify a command. Type 'help' for a list of commands.\n"));
+		}
+	}
+}
+
+void cmd() {
+	printf(F("You are now in command mode. Type 'help' for a list of commands.\n"));
+	while (Serial.available()) Serial.read();
+	while (1) {
+		command_loop();
+		delay(50);
+	}
+}

spybug/cmd.hh

@@ -0,0 +1,6 @@
+// Copyright 2022 Darwin Schuppan <darwin@nobrain.org>
+// SPDX license identifier: MIT
+
+#pragma once
+
+void cmd();

spybug/fstr.cpp

@@ -0,0 +1,37 @@
+// Copyright 2022 Darwin Schuppan <darwin@nobrain.org>
+// SPDX license identifier: MIT
+
+#include "fstr.hh"
+
+size_t fstrlen(const __FlashStringHelper *s) {
+	PGM_P sp = (PGM_P)s;
+	size_t len = 0;
+	while (pgm_read_byte(sp++))
+		len++;
+	return len;
+}
+
+bool fstreq(const char *a, const __FlashStringHelper *b_fsh) {
+	PGM_P b = (PGM_P)b_fsh;
+	while (1) {
+		if (*a != pgm_read_byte(b))
+			return false;
+		if (*a == 0)
+			return true;
+		a++; b++;
+	}
+}
+
+int printf(const __FlashStringHelper *fmt, ...) {
+	size_t len = fstrlen(fmt);
+	char buf[len + 1];
+	buf[len] = 0;
+	memcpy_P(buf, fmt, len + 1);
+
+	va_list args;
+	va_start(args, fmt);
+	int ret = vprintf(buf, args);
+	va_end(args);
+	return ret;
+}
+

spybug/fstr.hh

@@ -0,0 +1,12 @@
+// Copyright 2022 Darwin Schuppan <darwin@nobrain.org>
+// SPDX license identifier: MIT
+
+#pragma once
+
+#include <Arduino.h>
+
+size_t fstrlen(const __FlashStringHelper *s);
+
+bool fstreq(const char *a, const __FlashStringHelper *b_fsh);
+
+int printf(const __FlashStringHelper *fmt, ...);

spybug/io.cpp

@@ -0,0 +1,22 @@
+// Copyright 2022 Darwin Schuppan <darwin@nobrain.org>
+// SPDX license identifier: MIT
+
+#include "io.hh"
+
+static int serial_putch(char c, FILE *f) {
+	(void)f;
+	return Serial.write(c) == 1 ? 0 : 1;
+}
+
+static int serial_getch(FILE *f) {
+	(void)f;
+	while(Serial.available() == 0);
+	return Serial.read();
+}
+
+static FILE serial_in_out;
+
+void io_setup() {
+	fdev_setup_stream(&serial_in_out, serial_putch, serial_getch, _FDEV_SETUP_RW);
+	stdout = stdin = stderr = &serial_in_out;
+}

spybug/io.hh

@@ -0,0 +1,14 @@
+// Copyright 2022 Darwin Schuppan <darwin@nobrain.org>
+// SPDX license identifier: MIT
+
+#pragma once
+
+#include <Arduino.h>
+
+void io_setup();
+
+#define print_special(x) { Serial.print(x); }
+#define die(fmt, ...) { disable_recording_interrupts(); if (settings.serial_log) { printf(F("Fatal: ")); printf(fmt, ##__VA_ARGS__); Serial.flush(); } while(1); }
+#define dbg(fmt, ...) { printf(F("Debug: ")); printf(fmt, ##__VA_ARGS__); }
+#define info(fmt, ...) { if (settings.serial_log) printf(fmt, ##__VA_ARGS__); }
+#define info_special(x) { if (settings.serial_log) Serial.print(x); }

spybug/settings.cpp

@@ -0,0 +1,6 @@
+// Copyright 2022 Darwin Schuppan <darwin@nobrain.org>
+// SPDX license identifier: MIT
+
+#include "settings.hh"
+
+EEPROM_Settings_Class settings;

spybug/settings.hh

@@ -0,0 +1,17 @@
+// Copyright 2022 Darwin Schuppan <darwin@nobrain.org>
+// SPDX license identifier: MIT
+
+#pragma once
+
+#include <EEPROM.h>
+
+#define EEADDR_SETTINGS 0x00
+struct EEPROM_Settings_Class {
+	unsigned long recording_delay = 0l;
+	bool          serial_log      = true;
+
+	inline void load() { EEPROM.get(EEADDR_SETTINGS, *this); }
+	inline void save() { EEPROM.put(EEADDR_SETTINGS, *this); }
+};
+
+extern EEPROM_Settings_Class settings;

spybug/spybug.ino

@@ -30,110 +30,18 @@
 
 #include <SD.h>
 #include <SPI.h>
-#include <avr/interrupt.h>
-#include <avr/io.h>
-#include <avr/wdt.h>
 
-/************************
- BEGIN USER CONFIGURATION
- ************************/
-//#define DEBUG_RECORDING
-//#define SERIAL_OUTPUT
+#include "aaa_config.hh"
+#include "cmd.hh"
+#include "fstr.hh"
+#include "io.hh"
+#include "settings.hh"
+#include "sys.hh"
 
-//#define PIN_COMPONENT_SWITCH 2 /* Use a digital signal to switch on/off the microphone and SD card for less power draw. */
-//#define COMPONENT_SWITCH_ON HIGH
-
-#define SAMPLE_MODE_U8
-//#define SAMPLE_MODE_S16
-
-//#define ADC_PRESCALE_16 /* Up to ~60kHz. */
-//#define ADC_PRESCALE_32 /* Up to ~27kHz. */
-#define ADC_PRESCALE_64 /* Up to ~18kHz. */
-
-#define U8_EXTRA_PRECISION /* (U8 sampling mode only) use 9th ADC reading bit and chop off 1st bit for more precision (sacrificing half of the bandwidth) */
-
-#define RECORDING_DELAY_IN_MINUTES 0 /* Wait n minutes before starting to record. */
-#define ADC_CHANNEL AdcChannel0
-#define TIMER_COMPARE 1000 /* 16MHz / 1000 = 16kHz. */
-#define FLUSH_SAMPLES 64000 /* Flush WAV file every n samples. */
-#define PIN_SS 10
-/**********************
- END USER CONFIGURATION
- **********************/
-
-#ifdef SERIAL_OUTPUT
-static int serial_putch(char c, FILE *f) {
-	(void)f;
-	return Serial.write(c) == 1 ? 0 : 1;
-}
-
-static int serial_getch(FILE *f) {
-	(void)f;
-	while(Serial.available() == 0);
-	return Serial.read();
-}
-
-static FILE serial_in_out;
-
-static void setup_serial_in_out() {
-	fdev_setup_stream(&serial_in_out, serial_putch, serial_getch, _FDEV_SETUP_RW);
-	stdout = stdin = stderr = &serial_in_out;
-}
-
-static size_t fstrlen(const __FlashStringHelper *s) {
-	PGM_P sp = (PGM_P)s;
-	size_t len = 0;
-	while (pgm_read_byte(sp++))
-		len++;
-	return len;
-}
-
-static int printf(const __FlashStringHelper *fmt, ...) {
-	size_t len = fstrlen(fmt);
-	char buf[len + 1];
-	buf[len] = 0;
-	memcpy_P(buf, fmt, len + 1);
-
-	va_list args;
-	va_start(args, fmt);
-	int ret = vprintf(buf, args);
-	va_end(args);
-	return ret;
-}
-
-#define die(fmt, ...) { disable_recording_interrupts(); printf(F("Fatal: ")); printf(fmt, ##__VA_ARGS__); Serial.flush(); while(1); }
-#define dbg(fmt, ...) { printf(F("Debug: ")); printf(fmt, ##__VA_ARGS__); }
-#define print_special(x) Serial.print(x)
-#else
-#define printf(fmt, ...) {}
-#define die(fmt, ...) { disable_recording_interrupts(); while(1); }
-#define dbg(fmt, ...) {}
-#define print_special(x) {}
+#if !defined(__AVR_ATmega328P__) || F_CPU != 16000000
+#error "This program only works on ATmega328P devices with a clock frequency of 16MHz!"
 #endif
 
-#if defined(RECORDING_DELAY_IN_MINUTES) && RECORDING_DELAY_IN_MINUTES != 0
-#include <LowPower.h> /* https://github.com/rocketscream/Low-Power */
-static void low_power_sleep_minutes(unsigned long t) {
-	for (unsigned long i = 0; 8ul * i < 60ul * t; i++) {
-		/* Power down for 8s. */
-		LowPower.powerDown(SLEEP_8S, ADC_OFF, BOD_OFF);
-	}
-}
-#endif
-
-static void start_watchdog_with_full_reset() {
-	MCUSR &= ~B00001000; /* Clear reset flag. */
-	WDTCSR |= B00011000; /* Prepare prescaler change. */
-	WDTCSR = B00100001; /* Set watchdog timeout to 8s. */
-	// Enable Watchdog Timer
-	WDTCSR |= B01000000;
-	MCUSR = MCUSR & B11110111;
-}
-
-static inline void disable_recording_interrupts() {
-	TIMSK1 &= ~(_BV(OCIE1A) | _BV(OCIE1B));
-}
-
 enum AdcChannel : uint8_t {
 	AdcChannel0    = 0,
 	AdcChannel1    = 1,
@@ -177,9 +85,9 @@ ISR(TIMER1_COMPA_vect) {
 		sei();
 		const size_t bufsz = sizeof(SAMPLE_BUF_TYPE) * samples_in_buffer[!which_buffer];
 		if (file.write((char*)sample_buffer[!which_buffer], bufsz) != bufsz) {
-			printf(F("Lost "));
-			print_special((float)samples_hanging / (float)(F_CPU / TIMER_COMPARE)); /* Printf doesn't handle floats. */
-			printf(F(" seconds of recording.\n"));
+			info(F("Lost "));
+			info_special((float)samples_hanging / (float)(F_CPU / TIMER_COMPARE)); /* Printf doesn't handle floats. */
+			info(F(" seconds of recording.\n"));
 			die(F("Error writing to SD card. You can ignore this if you removed the SD card intentionally.\n"));
 		}
 		samples_hanging += samples_in_buffer[!which_buffer];
@@ -197,7 +105,7 @@ ISR(TIMER1_COMPA_vect) {
 ISR(TIMER1_COMPB_vect) {
 	// Retrieve ADC Value and Write to Buffer
 #if defined(SAMPLE_MODE_U8)
-#ifdef U8_EXTRA_PRECISION
+#ifdef U8_AMPLIFY_X2
 	uint8_t l = ADCL; /* Read ADC registers. (Order matters!) */
 	uint8_t h = ADCH;
 	uint8_t adcval = (h << 7) | (l >> 1);
@@ -270,30 +178,41 @@ static void wav_write_header(uint32_t nsamples) {
 
 void setup() {
 	// Serial Setup
-#ifdef SERIAL_OUTPUT
 	Serial.begin(9600); /* Set baud rate. */
-	setup_serial_in_out(); /* Add printf support. */
-#endif
+	io_setup(); /* Add printf support. */
 	// Component Switch Setup
 #ifdef PIN_COMPONENT_SWITCH
 	pinMode(PIN_COMPONENT_SWITCH, OUTPUT);
 #endif
-	// Delay Triggering
-#if defined(RECORDING_DELAY_IN_MINUTES) && RECORDING_DELAY_IN_MINUTES != 0
+	// Load EEPROM Data
+	settings.load();
+	// Handle Commands
+	info(F("Type anything in the next 4s to enter command mode.\n"));
+	for (size_t i = 0; i < 4 * 4; i++) {
+		if (Serial.available())
+			cmd();
+		delay(250);
+	}
+	// Delayed Triggering
+	if (settings.recording_delay) {
 #ifdef PIN_COMPONENT_SWITCH
-	digitalWrite(PIN_COMPONENT_SWITCH, !COMPONENT_SWITCH_ON);
-#endif
-	printf(F("Waiting %u minute%s before starting to record...\n"), RECORDING_DELAY_IN_MINUTES, RECORDING_DELAY_IN_MINUTES == 1 ? "" : "s");
-	Serial.flush();
-	low_power_sleep_minutes(RECORDING_DELAY_IN_MINUTES); /* Draws ~12.5mA instead of ~30mA when using delay(). */
+		digitalWrite(PIN_COMPONENT_SWITCH, !COMPONENT_SWITCH_ON);
 #endif
+		info(F("Sleeping for %lu minute%s before starting to record...\n"), settings.recording_delay, settings.recording_delay == 1 ? "" : "s");
+		Serial.flush();
+		/* Using this function, an Arduino Nano (with its voltage regulator and TTL module removed) draws ~6μA. */
+		low_power_sleep_minutes(settings.recording_delay);
+		/* Reset wait time. */
+		settings.recording_delay = 0;
+		settings.save();
+	}
 	// Activate Components
 #ifdef PIN_COMPONENT_SWITCH
 	digitalWrite(PIN_COMPONENT_SWITCH, COMPONENT_SWITCH_ON);
 	delay(500); /* Wait for components to initialize. */
 #endif
 	// Start Watchdog (wdt_enable() doesn't fully reset)
-	start_watchdog_with_full_reset();
+	wdt_enable_with_full_reset();
 	// SD Card Setup
 	if (!SD.begin(PIN_SS))
 		die(F("Error initializing SD card!\n"));
@@ -302,11 +221,11 @@ void setup() {
 	char filename[32];
 	do {
 		filenum++;
-		snprintf(filename, 32, "rec_%03u.wav", filenum);
+		snprintf(filename, 32, REC_FILE_FMT, filenum);
 	} while (SD.exists(filename));
 	// Open File
 	file = SD.open(filename, O_READ | O_WRITE | O_CREAT); /* Seeking doesn't seem to work with FILE_WRITE?! */
-	printf(F("Recording to file '%s'.\n"), filename);
+	info(F("Recording to file '%s'.\n"), filename);
 	if (!file)
 		die(F("Error opening '%s' for writing!\n"), filename);
 	wav_write_header(0);
@@ -323,7 +242,7 @@ void setup() {
 #endif
 	ADCSRB = _BV(ADTS2) | _BV(ADTS0); /* Auto-trigger source select: "Timer/Counter1 Compare Match B". */
 	ADMUX = _BV(REFS0) /* Use AREF pin (VCC by default) as reference voltage. */
-#if defined(SAMPLE_MODE_U8) && !defined(U8_EXTRA_PRECISION)
+#if defined(SAMPLE_MODE_U8) && !defined(U8_AMPLIFY_X2)
 	      | _BV(ADLAR) /* Left adjust ADC output so we only need to read ADCH. */
 #endif
 		  | (0xF & ADC_CHANNEL); /* Select our ADC input channel. */
@@ -336,8 +255,9 @@ void setup() {
 	       | _BV(OCIE1B); /* Enable "Output Compare B Match Interrupt". */
 }
 
+
 void loop() {
-	delay(1000);
+	delay(2000);
 	wdt_reset(); /* Reset watchdog timer. */
 #ifdef DEBUG_RECORDING
 	dbg(F("n=%lu\tavg=%lu\tmin=%d\tmax=%d\n"), dbg_total, dbg_sum / (dbg_samples ? dbg_samples : 1), dbg_min, dbg_max);
@@ -346,5 +266,5 @@ void loop() {
 	dbg_min = 32767;
 	dbg_max = -32768;
 #endif
-	printf(F("samples: written=%lu, hanging=%lu, dropped=%lu\n"), samples_written, samples_hanging, samples_dropped);
+	info(F("samples: written=%lu, hanging=%lu, dropped=%lu\n"), samples_written, samples_hanging, samples_dropped);
 }

spybug/sys.cpp

@@ -0,0 +1,37 @@
+// Copyright 2022 Darwin Schuppan <darwin@nobrain.org>
+// SPDX license identifier: MIT
+
+#include "sys.hh"
+
+void (*full_reset)() = nullptr;
+
+static volatile bool wdt_in_sleep_mode = false;
+ISR (WDT_vect) {
+	if (wdt_in_sleep_mode)
+		wdt_disable();
+	else
+		full_reset();
+}
+
+/* Based on https://github.com/rocketscream/Low-Power. */
+void low_power_sleep_minutes(unsigned long t) {
+	wdt_in_sleep_mode = true;
+	ADCSRA &= ~_BV(ADEN); /* Disable ADC. */
+	for (unsigned long i = 0; 8ul * i < 60ul * t; i++) {
+		// Power Down for 8s
+		wdt_enable(WDTO_8S);   /* Start watchdog timer for 8s. */
+		WDTCSR |= (1 << WDIE); /* Enable watchdog interrupt. */
+		do {
+			set_sleep_mode(SLEEP_MODE_PWR_DOWN);
+			cli();
+			sleep_enable();
+			sleep_bod_disable();
+			sei();
+			sleep_cpu();
+			sleep_disable();
+			sei();
+		} while (0);
+	}
+	ADCSRA |= _BV(ADEN); /* Re-enable ADC. */
+	wdt_in_sleep_mode = false;
+}

spybug/sys.hh

@@ -0,0 +1,22 @@
+// Copyright 2022 Darwin Schuppan <darwin@nobrain.org>
+// SPDX license identifier: MIT
+
+#pragma once
+
+#include <avr/interrupt.h>
+#include <avr/io.h>
+#include <avr/wdt.h>
+#include <avr/sleep.h>
+
+extern void (*full_reset)();
+
+void low_power_sleep_minutes(unsigned long t);
+
+static inline void wdt_enable_with_full_reset() {
+	wdt_enable(WDTO_8S);   /* Start watchdog timer for 8s. */
+	WDTCSR |= (1 << WDIE); /* Enable watchdog interrupt. */
+}
+
+static inline void disable_recording_interrupts() {
+	TIMSK1 &= ~(_BV(OCIE1A) | _BV(OCIE1B));
+}