commit 8f258e4e02e1821692d39d87d4073e884bc2798a
parent 9d751dc020b43f32b1cd7e5216f4d8de0208dda0
Author: Vineet K <git@vineetk.net>
Date: Wed, 17 Apr 2024 10:07:39 -0400
use timer1 ctc mode instead of util/delay functions
Diffstat:
| M | Makefile | | | 2 | ++ |
| M | main.c | | | 70 | +++++++++++++++++++++++++++++++++++++++------------------------------- |
2 files changed, 41 insertions(+), 31 deletions(-)
diff --git a/Makefile b/Makefile
@@ -2,6 +2,8 @@ CC = avr-gcc
CFLAGS = -O2 -Wall -Wextra -Werror -mmcu=atmega328p
OBJCOPY = avr-objcopy
+PORT ?= /dev/ttyACM0
+
all:
${CC} ${CFLAGS} main.c
${OBJCOPY} -j .text -j .data -O ihex a.out main.hex
diff --git a/main.c b/main.c
@@ -1,43 +1,42 @@
/*
* EEL4746C - AVR Piano - Speaker Section
* speaker is connected to PD2 and ground
- * buttons are connected to PB0-5, PC0-5, PD3-7
+, PD3-7
* the LCD Arduino UNO is connected to TX/RX (PD0/1)
*/
#include <avr/io.h>
#include <avr/interrupt.h>
-#define F_CPU 16000000UL
-#define __DELAY_BACKWARD_COMPATIBLE__ /* to use variables with _delay_u/ms */
-#include <util/delay.h>
+#define T1_PRESCALAR 8
+#define FREQ(f) (16e6 / f / T1_PRESCALAR / 2)
-#define P_RX 0
-#define P_TX 1
-#define P_SPKR 2
+#define P_RX 0
+#define P_TX 1
+#define P_SPKR 2
unsigned short freqs[] = {
- 1 / 100 * 1e6 / 2,
- 1 / 200 * 1e6 / 2,
- 1 / 250 * 1e6 / 2,
- 1 / 300 * 1e6 / 2,
- 1 / 350 * 1e6 / 2,
- 1 / 400 * 1e6 / 2,
- 1 / 500 * 1e6 / 2,
- 1 / 600 * 1e6 / 2,
- 1 / 700 * 1e6 / 2,
- 1 / 750 * 1e6 / 2,
- 1 / 1000 * 1e6 / 2,
- 1 / 1250 * 1e6 / 2,
- 1 / 1500 * 1e6 / 2,
- 1 / 1750 * 1e6 / 2,
- 1 / 2000 * 1e6 / 2,
- 1 / 3000 * 1e6 / 2,
- 1 / 4000 * 1e6 / 2,
- 1 / 5000 * 1e6 / 2,
- 1 / 6000 * 1e6 / 2,
- 1 / 7000 * 1e6 / 2,
- 1 / 8000 * 1e6 / 2
+ FREQ(100),
+ FREQ(200),
+ FREQ(250),
+ FREQ(300),
+ FREQ(350),
+ FREQ(400),
+ FREQ(500),
+ FREQ(600),
+ FREQ(700),
+ FREQ(750),
+ FREQ(1000),
+ FREQ(1250),
+ FREQ(1500),
+ FREQ(1750),
+ FREQ(2000),
+ FREQ(3000),
+ FREQ(4000),
+ FREQ(5000),
+ FREQ(6000),
+ FREQ(7000),
+ FREQ(8000),
};
unsigned char note = 8;
unsigned char buttonpressed = 1;
@@ -54,15 +53,24 @@ main(void)
PCMSK2 = ~(1 | (1 << 1) | (1 << 2));
PCICR = (1 << PCIE0) | (1 << PCIE1) | (1 << PCIE2);
+ TCCR1A = 0x00; // use timer1 CTC mode
+ TCCR1B = 1 << WGM12; // already prescaled by 8 in table
+
sei();
//for (;;);
for (unsigned char n = 0;; n = (n + 1) % 2) {
if (!buttonpressed && n == 0) continue;
- _delay_us(freqs[note]);
-// _delay_us(714.2857);
-// _delay_us(70);
+
+ TCNT1 = 1;
+ OCR1A = freqs[note];
+ TCCR1B |= 1 << CS11;
+
+ while ((TIFR1 & (1 << OCF1A)) == 0);
+
PORTD ^= 1 << P_SPKR;
+ TIFR1 |= 1 << OCF1A;
+ TCCR1B &= ~(1 << CS11);
}
}
