From 2f7a1e89aa19dac7903e743e60b275a54a0230cf Mon Sep 17 00:00:00 2001
From: Scott Worley <scottworley@scottworley.com>
Date: Sun, 8 Oct 2023 19:15:49 -0700
Subject: [PATCH] client: debounce

---
 client/config.c    |  4 ++++
 client/config.h    |  4 ++++
 client/tattlekey.c | 14 ++++++++++----
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/client/config.c b/client/config.c
index a8e5844..c5a38b4 100644
--- a/client/config.c
+++ b/client/config.c
@@ -17,3 +17,7 @@ u16_t this_tattler_identity = 1;
  * https://projects.raspberrypi.org/en/projects/introduction-to-the-pico/10
  * recommends pins 18, 22, or 28. */
 uint button_pin = 18;
+
+/* Don't bother reporting each separate button press when it is pressed many
+ * times in short succession.  (We also use this to de-bounce. :) */
+u32_t minimum_microseconds_between_button_presses = 1000000;
diff --git a/client/config.h b/client/config.h
index 95c5651..5ce0baf 100644
--- a/client/config.h
+++ b/client/config.h
@@ -21,4 +21,8 @@ extern u16_t this_tattler_identity;
  * recommends pins 18, 22, or 28. */
 extern uint button_pin;
 
+/* Don't bother reporting each separate button press when it is pressed many
+ * times in short succession.  (We also use this to de-bounce. :) */
+extern u32_t minimum_microseconds_between_button_presses;
+
 #endif
diff --git a/client/tattlekey.c b/client/tattlekey.c
index 45059f6..ff61f43 100644
--- a/client/tattlekey.c
+++ b/client/tattlekey.c
@@ -11,10 +11,16 @@ queue_t queue;
 
 static void button_pressed() {
   /* This runs in interrupt context; don't linger.  */
-  char zero = '\0';
-  /* We don't check for failure (full queue) here because there's not much to be
-   * done about it. */
-  queue_try_add(&queue, &zero);
+  static uint64_t last_button_press_time = 0;
+  uint64_t now = time_us_64();
+  uint64_t time_since_last_press = now - last_button_press_time;
+  if (time_since_last_press > minimum_microseconds_between_button_presses) {
+    last_button_press_time = now;
+    char zero = '\0';
+    /* We don't check for failure (full queue) here because there's not much to
+     * be done about it. */
+    queue_try_add(&queue, &zero);
+  }
 }
 
 int main() {
-- 
2.44.1