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Add NPN buzzer projects

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This commit is contained in:
Andrew Kesterson
2026-05-28 08:13:57 -04:00
parent 61913ae3cc
commit 6c0ba3dbe0
3 changed files with 47 additions and 1 deletions
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31
activebuzzer_npn_lowside_switching/activebuzzer_npn_lowside_switching.ino Normal file
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@@ -0,0 +1,31 @@
#define PIN_BUZZER_SWITCH 14
#define PIN_BUTTON 21
#define PWM_CHANNEL 0
void setup() {
pinMode(PIN_BUZZER_SWITCH, OUTPUT);
pinMode(PIN_BUTTON, INPUT);
// Tutorial had a bug here. Needs to be freq=1000, not freq=1.
ledcAttachChannel(PIN_BUZZER_SWITCH, 1000, 10, PWM_CHANNEL);
ledcWriteTone(PIN_BUZZER_SWITCH, 2000);
delay(300);
}
void alarm() {
float sine;
int tone;
for ( int i = 0; i < 360 ; i += 10 ) {
sine = sin(i * (PI / 180));
tone = 2000 + sine * 500;
ledcWriteTone(PIN_BUZZER_SWITCH, tone);
delay(50);
}
}
void loop() {
if ( digitalRead(PIN_BUTTON) == LOW ) {
alarm();
} else {
ledcWriteTone(PIN_BUZZER_SWITCH, 0);
}
}

15
buzzer-npn-lowside-switching/buzzer-npn-lowside-switching/buzzer-npn-lowside-switching.ino Normal file
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@@ -0,0 +1,15 @@
#define PIN_BUZZER_SWITCH 14
#define PIN_BUTTON 21
void setup() {
pinMode(PIN_BUZZER_SWITCH, OUTPUT);
pinMode(PIN_BUTTON, INPUT);
}
void loop() {
if ( digitalRead(PIN_BUTTON) == LOW ) {
digitalWrite(PIN_BUZZER_SWITCH, HIGH);
} else {
digitalWrite(PIN_BUZZER_SWITCH, LOW);
}
}

2
flowing_light_with_button/README.md
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@@ -31,7 +31,7 @@ if (digitalRead(PIN_BUTTON) == LOW) {
// do something with the pin
```
... This is really wasteful. I paid good money for those CPU cycles, and on embedded hardware we don't have a lot of them to go around. (The ESP32-S3 has an Xtensa dual-core 32-bit LX7 running up to 240Mhz - stunning when you think about the price and size of the package, but still, not enough to be wasteful.) I improved that by using a timer in a function that yields time back to the CPU while it's waiting to verify that the button is debounced.
... This is not great. First, we are wasting CPU cycles (The ESP32-S3 has an Xtensa dual-core 32-bit LX7 running up to 240Mhz - stunning when you think about the price and size of the package, but still, not enough to be wasteful). But on the ESP32-S3 in particular, the solution package as a whole isn't losing those cycles - it runs Arduino on top of an RTOS, so `delay()` is actually yielding back to the RTOS scheduler so that things like bluetooth and wifi stacks can continue. But *our* program is fully blocked here. If I want to scan additional buttons, or perform some other task, we're locked in here. So I improved that by using a timer in a function that yields time back to the CPU while it's waiting to verify that the button is debounced.
```arduino
void checkButtonPressed(void) {