From edd35cae3b841281d5f1754cd5eb7cabfa7c8b16 Mon Sep 17 00:00:00 2001
From: Vineet K <git@vineetk.net>
Date: Sat, 20 Apr 2024 00:01:55 -0400
Subject: [PATCH] update UART code to send note and #cycles played

Besides moving the UART into an interrupt, we also need to read from
UART to set the mode of playing from buttons or from serial notes
---
 Makefile |  6 ++++++
 notes.c  | 30 ++++++++++++++++++------------
 2 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/Makefile b/Makefile
index 2c74da6..1731fcc 100644
--- a/Makefile
+++ b/Makefile
@@ -21,3 +21,9 @@ lcd:
 
 flash_lcd: notes
 	avrdude -p atmega328p -c arduino -P ${PORT} -b 115200 -U flash:w:lcd.hex:i
+
+serial_setup:
+	stty -F ${PORT} raw speed 115200 cs8 -cstopb -parenb
+
+serial_open:
+	od -x --endian=big -w4 ${PORT}
diff --git a/notes.c b/notes.c
index 946ecd6..c677c9a 100644
--- a/notes.c
+++ b/notes.c
@@ -19,27 +19,25 @@
 #define P_SPKR		2
 
 unsigned short freqs[] = {
+	// PD3-7
 	FREQ(100),
 	FREQ(200),
 	FREQ(250),
 	FREQ(300),
 	FREQ(350),
+	// PB0-4
 	FREQ(400),
 	FREQ(500),
 	FREQ(600),
 	FREQ(700),
 	FREQ(750),
+	// PC0-4
 	FREQ(1000),
 	FREQ(1250),
 	FREQ(1500),
 	FREQ(1750),
 	FREQ(2000),
-	FREQ(3000),
-	FREQ(4000),
-	FREQ(5000),
-	FREQ(6000),
-	FREQ(7000),
-	FREQ(8000),
+
 	[255] = 0	// used as a 'silent' note
 };
 unsigned char note = 0;
@@ -60,7 +58,7 @@ ISR (PCINT1_vect)
 	// check if any button in the whole port is pressed
 	for (unsigned char i = 0; i <= 5; i++) {
 		if (PINC & (1 << i)) {
-			note = i + 5 + 6;
+			note = i + 10;
 			break;
 		}
 	}
@@ -123,13 +121,24 @@ main(void)
 
 	// Sends Square wave to the Speaker When a Button is Pressed
 	unsigned short cycles = 0;
+	unsigned char last_note = 0;
 	for (unsigned char n = 0;; n = (n + 1) % 2) {
 		// check if any buttons are pressed, otherwise don't play a note
-		if (((PINB & PCMSK0) | (PINC & PCMSK1) | (PIND & PCMSK2)) == 0)
+		if (((PINB & PCMSK0) | (PINC & PCMSK1) | (PIND & PCMSK2)) == 0) {
+			// if a button was released, then send note and cycles played
+			if (cycles > 0) {
+				usart_send(last_note);
+				usart_send(HIGH(cycles));
+				usart_send(LOW(cycles));
+				usart_send('\xff');
+				cycles = 0;
+			}
 			continue;
-		
+		}
+
 		// Prepare Timer/Counter
 		TCNT1 = 1;
+		last_note = note;
 		OCR1A = freqs[note];
 		TCCR1B |= 1 << CS11;
 
@@ -140,8 +149,5 @@ main(void)
 		TIFR1 |= 1 << OCF1A;
 		TCCR1B &= ~(1 << CS11);
 		cycles = (cycles + 1) % 0xffff;
-
-		usart_send(HIGH(cycles));
-		usart_send(LOW(cycles));
 	}
 }