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Andrew Kesterson
2026-05-28 08:15:51 -04:00
parent 6c0ba3dbe0
commit 9958e9a3b9
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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 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.
... This is not great. On simpler microcontrollers, `delay()` burns 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) {