read and play notes from serial

1 files changed, 32 insertions, 14 deletions

diff --git a/notes.c b/notes.c
index 3f93cc5..7902efe 100644
--- a/notes.c
+++ b/notes.c
@@ -38,12 +38,12 @@ unsigned short freqs[] = {
         FREQ(1750),
         FREQ(2000),
 
-        [255] = 0       // used as a 'silent' note
+        [32] = 0        // used as a 'silent' note
 };
 unsigned char note = 0;
 // 0 = buttons write note+cycles+\xff to UART
 // 1 = buttons don't do anything, speaker reads note+cycles+\xff from UART
-unsigned char mode = 0;
+unsigned char mode = '0';
 
 ISR (PCINT0_vect)
 {
@@ -82,7 +82,7 @@ void
 usart_init(void)
 {
         // 115200 bps, RX/TX enabled
-        UBRR0 = 8;
+        UBRR0 = 103;
         UCSR0B = (1 << RXEN0) | (1 << TXEN0);
         UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);
 }
@@ -94,6 +94,13 @@ usart_send(unsigned char c)
         UDR0 = c;
 }
 
+void
+usart_send_str(const char *c)
+{
+        for (unsigned char i = 0; c[i] != '\0'; i++)
+                usart_send(c[i]);
+}
+
 unsigned char
 usart_read(void)
 {
@@ -125,9 +132,14 @@ main(void)
         // Sends Square wave to the Speaker When a Button is Pressed
         unsigned short cycles = 0;
         unsigned char tmp = 0;
-        for (;;) {
+        for (unsigned char n = 0;; n = (n + 1) % 2) {
+                if (UCSR0A & (1 << RXC0)) {
+                        mode = UDR0;
+                        PORTD &= ~(1 << P_SPKR);
+                        usart_send(mode);
+                }
                 // check if any buttons are pressed, otherwise don't play a note
-                if (((PINB & PCMSK0) | (PINC & PCMSK1) | (PIND & PCMSK2)) == 0) {
+                if (mode != '1' && ((PINB & PCMSK0) | (PINC & PCMSK1) | (PIND & PCMSK2)) == 0) {
                         // if a button was released, then send note and cycles played
                         if (cycles > 0) {
                                 usart_send(tmp);
@@ -135,16 +147,11 @@ main(void)
                                 usart_send(LOW(cycles));
                                 usart_send(0xff);
                                 cycles = 0;
-                        } else {
-                                if (UCSR0A & (1 << RXC0)) {
-                                        mode = UDR0;
-                                        usart_send(mode);
-                                }
                         }
                         continue;
                 }
 
-                if (mode == 0) {
+                if (mode == '0') {
                         // Prepare Timer/Counter
                         TCNT1 = 1;
                         tmp = note;
@@ -159,15 +166,26 @@ main(void)
                         TIFR1 |= 1 << OCF1A;
                         TCCR1B &= ~(1 << CS11);
                         cycles = (cycles + 1) % 0xffff;
-                } else if (mode == 0xb0) {
+                } else if (mode == '1') {
                         note = usart_read();
+                        if (note >= '0') note -= '0';
                         tmp = usart_read();
                         cycles = tmp << 8;
                         tmp = usart_read();
                         cycles |= tmp;
-                        (void)usart_read();
+                        tmp = usart_read();
+
+                        // reset to default mode when an invalid note is read
+                        if (tmp != 'z' || note > '@') {
+                                mode = '0';
+                                continue;
+                        }
+
+                        for (unsigned short i = 0; i < cycles; i++) {
+                                usart_send(HIGH(cycles));
+                                usart_send(LOW(cycles));
+                                usart_send(0);
 
-                        for (unsigned char i = 0; i < cycles; i++) {
                                 TCNT1 = 1;
                                 OCR1A = freqs[note];
                                 TCCR1B |= 1 << CS11;