tests: driversik; gpio-async: Implement basic debounce

To avoid spurious press/releases, use a simple loop to debounce the keys
each time they change.  This fairly closely models how a keyboard will
really work.

Ideally, this should be able to block on multiple gpios, however, with
the current use of the gpio-token, it is only possible to have a single
call outstanding.

Signed-off-by: David Brown <[email protected]>

Author: d3zd3z

tests/drivers/gpio-async/src/lib.rs

@@ -5,7 +5,9 @@
 
 extern crate alloc;
 
+use embassy_time::{Duration, Ticker};
 use zephyr::{
+    device::gpio::{GpioPin, GpioToken},
     embassy::Executor,
     raw::{GPIO_INPUT, GPIO_OUTPUT_ACTIVE, GPIO_PULL_DOWN},
 };
@@ -45,8 +47,31 @@ async fn main(spawner: Spawner) {
 
     loop {
         unsafe { row0.wait_for_high(&mut gpio_token).await };
+        // Simple debounce, Wait for 20 consecutive high samples.
+        debounce(&mut row0, &mut gpio_token, true).await;
         info!("Pressed");
         unsafe { row0.wait_for_low(&mut gpio_token).await };
+        debounce(&mut row0, &mut gpio_token, false).await;
         info!("Released");
     }
 }
+
+/// Simple debounce.  Scan the gpio periodically, and return when we have 20 consecutive samples of
+/// the intended value.
+async fn debounce(pin: &mut GpioPin, gpio_token: &mut GpioToken, level: bool) {
+    let mut count = 0;
+    let mut ticker = Ticker::every(Duration::from_millis(1));
+    loop {
+        ticker.next().await;
+
+        if unsafe { pin.get(gpio_token) } == level {
+            count += 1;
+
+            if count >= 20 {
+                return;
+            }
+        } else {
+            count = 0;
+        }
+    }
+}