Interrupts for rotary encoder and buttons, timer0 based sound generat…

…or, timer1 based tap tempo, basic metronome

README.md

@@ -1 +1,5 @@
-# metronome
+# metronome
+
+```
+make flash
+```

interrupts.h

@@ -0,0 +1,97 @@
+#ifndef __interrupts_h__
+#define __interrupts_h__
+
+ISR(PCINT2_vect) {
+    clearBit(SPEAKER_DIR, SPEAKER);
+    bool btnPushed = bit_is_clear(ROTARY_PIN, ROTARY_BTN);
+    if (bit_is_clear(ROTARY_PIN, ROTARY_A))
+    {
+        if (bit_is_clear(ROTARY_PIN, ROTARY_B))
+        {
+            if (btnPushed)
+            {
+                if (cursor)
+                {
+                    --cursor;
+                }
+                else
+                {
+                    cursor = 3u;
+                }
+            }
+            else
+            {
+                updateActiveParam(-1);
+            }
+        }
+        else
+        {
+            if (btnPushed)
+            {
+                ++cursor;
+                cursor %= 4u;
+            }
+            else
+            {
+                updateActiveParam(1);
+            }
+        }
+
+        t_beep = 6000u / bpm;
+        t_sleep = 54000u / bpm;
+
+        update_display();
+        // force a little down time before continuing
+        _delay_ms(2);
+        // wait until R1 comes back high
+        while (bit_is_clear(ROTARY_PIN, ROTARY_A))
+            ;
+    }
+
+    if (bit_is_clear(TAP_PIN, TAP_BTN))
+    {
+        sound_locked = false;
+        play_note(120u, t_beep);
+        sound_locked = true;
+        // tap tempo handler
+        if (tap_started)
+        {
+            if (tap_interval_counter < 2001u && tap_interval_counter > 130u)
+            {
+                t_beep = tap_interval_counter >> 4;
+                t_sleep = tap_interval_counter - t_beep;
+                bpm = 60000u / tap_interval_counter;
+                update_display();
+            }
+        }
+        else
+        {
+            tap_started = true;
+            sound_locked = true;
+        }
+        // start counting
+        tap_interval_counter = 0u;
+        //TCCR2A = 0;
+        TCCR2B = 0x4;
+        TCNT2 = TAP_TIMER_INITIAL_OFFSET; // 131 ticks until overflow
+    }
+}
+
+// tap tempo timer (1ms) overflow
+ISR(TIMER2_OVF_vect)
+{
+    if (tap_interval_counter < 2001u)
+    {
+        ++tap_interval_counter;
+        TCNT2 = TAP_TIMER_INITIAL_OFFSET;
+    }
+    else
+    {
+        // dismiss tap tempo in case of timeout (over 2000ms)
+        tap_started = false;
+        TCCR2B &= ~(TCCR2B & 0x7);
+        sound_locked = false;
+    }
+}
+
+#endif //__interrupts_h__

lcd.c

@@ -55,15 +55,15 @@ void lcd_init(void) {
     _delay_ms(2);
 }
 
-void lcd_string(char *str) {
+void lcd_string(char * str) {
     int i;
     for (i = 0; str[i] != 0; i++) /* Send each char of string till the NULL */
     {
         lcd_char(str[i]);
     }
 }
 
-void lcd_string_xy(char row, char pos, char *str) {
+void lcd_string_xy(char row, char pos, char * str) {
     if (row == 0 && pos < 16)
         lcd_command((pos & 0x0F) | LCD_FIRST_LINE); /* Command of first row and required position<16 */
     else if (row == 1 && pos < 16)

lcd.h

@@ -1,7 +1,8 @@
 #ifndef __lcd_h__
 #define __lcd_h__
 
-#define LCD_FIRST_LINE 0x80
+#define LCD_SIZE        16u
+#define LCD_FIRST_LINE  0x80
 #define LCD_SECOND_LINE 0xC0
 
 void lcd_init(void);
@@ -12,8 +13,8 @@ void lcd_char(unsigned char data);
 
 void lcd_clear(void);
 
-void lcd_string(char *str);
+void lcd_string(char * str);
 
-void lcd_string_xy(char row, char pos, char *str);
+void lcd_string_xy(char row, char pos, char * str);
 
 #endif //__lcd_h__

main.c

@@ -1,7 +1,153 @@
+#define F_CPU 8000000
+
+#ifndef BAUD
+#define BAUD 9600
+#endif
+
+#include <util/setbaud.h>
+#include <util/delay.h>
+#include <avr/power.h>
+#include <avr/interrupt.h>
+#include <stdio.h>
+
 #include "util.h"
 #include "setup.h"
+#include "lcd.h"
+
+volatile uint8_t    cursor;
+volatile uint16_t   bpm;
+volatile uint8_t    signature; // e.g. 0100 0100 for 4/4 time signature
+volatile uint16_t   t_beep;
+volatile uint16_t   t_sleep;
+volatile uint8_t    volume;
+volatile uint16_t   tap_interval_counter;
+volatile bool       tap_started;
+volatile bool       sound_locked;
+uint8_t             signatures[2] = { 0x44, 0x34 };
+char                firstLineBuffer[LCD_SIZE+1];
+char                secondLineBuffer[LCD_SIZE+1];
+
+static void setup(void);
+
+static void loop(void);
+
+inline static void update_display(void) {
+    snprintf(firstLineBuffer, 17, "%c %3uBPM %c %2u/%1u ",
+             cursorVisible(cursor, 0),
+             bpm,
+             cursorVisible(cursor, 1),
+             signatures[signature] >> 4,
+             signatures[signature] & 0x0f);
+    snprintf(secondLineBuffer, 17, "%c %3u%%  %c  %s",
+             cursorVisible(cursor, 2),
+             volume,
+             cursorVisible(cursor, 3),
+             "SOUND");
+    lcd_string_xy(0, 0, firstLineBuffer);
+    lcd_string_xy(1, 0, secondLineBuffer);
+}
+
+static void updateActiveParam(int delta) {
+    switch (cursor) {
+    case 0u:
+        if (bpm > 80u && bpm < 350u)
+            bpm += delta;
+        break;
+    case 1u:
+        signature += delta;
+        signature %= 2;
+        break;
+    case 2u:
+        if (volume > 0u && volume < 100u)
+            volume += delta;
+        break;
+    case 3u:
+        break;
+    default:
+        break;
+    }
+}
+
+inline static void init_interrupts(void) {
+    // enable pin change interrupts on PORTD
+    PCICR |= (1 << PCIE2);
+
+    // pin change interrupt mask
+    PCMSK2 |= ((1 << ROTARY_A) | (1 << ROTARY_B) | (1 << TAP_BTN));
+
+    // enable interrupts globally
+    sei();
+}
+
+inline static void init_tap_timer(void) {
+    TIMSK2 = (1 << TOIE2);
+}
+
+inline static void init_sound_timer(void) {
+    setBit(TCCR0A, WGM01);
+    setBit(TCCR0A, COM0A0);
+    setBit(TCCR0B, CS00);
+    setBit(TCCR0B, CS01);
+}
+
+inline static void play_note(uint8_t wavelength, uint8_t duration) {
+    OCR0A = wavelength;
+    if (!sound_locked) {
+        setBit(SPEAKER_DIR, SPEAKER);
+        while (duration) {
+            _delay_ms(1u);
+            --duration;
+        }
+        clearBit(SPEAKER_DIR, SPEAKER);
+    }
+}
+
+// IMPORTANT: this must be included right here
+#include "interrupts.h"
 
 int main(void) {
-    while (true);
+    setup();
+    loop();
     return (0);
-}
+}
+
+static void setup(void) {
+    // clk / 1
+    clock_prescale_set(CLK_NO_DIVIDE);
+
+    // TODO Read stored settings from internal EEPROM
+    cursor = 0u;
+    bpm = DEFAULT_BPM;
+    volume = DEFAULT_VOL;
+    signature = DEFAULT_SIGNATURE;
+    t_beep = 6000u / bpm;
+    t_sleep = 54000u / bpm;
+    tap_interval_counter = 0u;
+    tap_started = false;
+    sound_locked = false;
+
+    lcd_init();
+    init_tap_timer();
+    init_sound_timer();
+    init_interrupts();
+
+    setInputPullup(ROTARY_DIR, ROTARY_PORT, ROTARY_A);
+    setInputPullup(ROTARY_DIR, ROTARY_PORT, ROTARY_B);
+    setInputPullup(ROTARY_DIR, ROTARY_PORT, ROTARY_BTN);
+    setInputPullup(TAP_DIR, TAP_PORT, TAP_BTN);
+
+    update_display();
+}
+
+static void loop(void) {
+    uint8_t i = 0u;
+    while (true) {
+        play_note(100u, t_beep);
+        _delay_ms(t_sleep);
+        for (i = 0u; i < (signatures[signature] >> 4) - 1; ++i) {
+            play_note(120u, t_beep);
+            _delay_ms(t_sleep);
+        }
+    }
+}
+

setup.h

@@ -1,12 +1,6 @@
 #ifndef __setup_h__
 #define __setup_h__
 
-#define F_CPU 8000000
-
-#ifndef BAUD
-#define BAUD 9600
-#endif
-
 #define LCD_DIR         DDRC  
 #define LCD_PORT        PORTC 
 #define RS              PC4 
@@ -31,4 +25,8 @@
 
 #define TAP_TIMER_INITIAL_OFFSET 0x83
 
+#define DEFAULT_BPM         140u
+#define DEFAULT_VOL         50u
+#define DEFAULT_SIGNATURE   0
+
 #endif //__setup_h__

util.h

@@ -12,4 +12,8 @@
 
 #define setInputPullup(ddr, port, pin) clearBit((ddr),(pin));setBit((port),(pin))
 
+#define cursorVisible(cursorPos, currentPos) ((cursorPos) == (currentPos)) ? '>' : ' '
+
+#define CLK_NO_DIVIDE 0
+
 #endif //__util_h__