+extern const u16_t config_this_tattler_identity;
+
+/* Which GPIO pin is the button connected to?
+ * The button should span this pin and ground, connecting this pin to ground
+ * when pressed.
+ * https://projects.raspberrypi.org/en/projects/introduction-to-the-pico/10
+ * recommends pins 18, 22, or 28. */
+extern const uint config_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 const u32_t config_minimum_seconds_between_button_presses;
+
+/* Send each report multiple times. Re-sends are sent with exponential delay:
+ * #1 sent immediately
+ * #2 after 1 seconds
+ * #3 after 2 seconds
+ * #4 after 4 seconds
+ * #5 after 8 seconds
+ * ...
+ * #11 after 8 minutes
+ * #12 after 17 minutes
+ * #13 after 34 minutes
+ * #14 after 68 minutes
+ * #15 after 2 hours
+ * #16 after 4 hours
+ * #17 after 9 hours
+ * etc.
+ * This provides some robustness against network outages, automatically
+ * replaying the log periodically to be collected after connectivity
+ * is restored. */
+extern const uint config_resend_count;
+
+/* These control the size of the per-send-count press queues.
+When the button is pressed more than config_maximum_queue_size times
+within the resend interval, some presses will be reported fewer
+than config_resend_count times. This is usually fine because it's
+the old, longest-delyed, most-redundant reports that get dropped;
+fresh, timely reports of new button presses will not get anywhere near
+config_resend_count in a resend interval because the early resend interals
+are so short. */
+extern const uint config_maximum_queue_size;
+
+/* This is paranoia about unanticipated delays. Setting this to zero
+would pobably be fine, but imposing a minimum queue size is an easy
+safety measure. */
+extern const uint config_minimum_queue_size;