commit 21992cfc5410263750b481044ea77c431adff8d0
parent d129c76966fc961672831a3058c79e76c93d7019
Author: Vineet K <git@vineetk.net>
Date: Sun, 21 Apr 2024 17:22:43 -0400
read and play notes from serial
Diffstat:
| M | notes.c | | | 46 | ++++++++++++++++++++++++++++++++-------------- |
1 file changed, 32 insertions(+), 14 deletions(-)
diff --git 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;
