From 9fc40fd8000fa48977d7b01d538d94456d6939e5 Mon Sep 17 00:00:00 2001
From: Pim van Pelt <pim@ipng.nl>
Date: Tue, 28 Nov 2017 15:32:27 +0100
Subject: [PATCH] New implementation of backlight based on persistent keepalive
 timer, rather than oneshot timer

---
 include/backlight.h |  3 +--
 src/backlight.c     | 27 ++++++++++++++++++---------
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/include/backlight.h b/include/backlight.h
index a3d616d..8a7ceb8 100644
--- a/include/backlight.h
+++ b/include/backlight.h
@@ -7,10 +7,9 @@
 #include "mgos_timers.h"
 
 #define BACKLIGHT_PWM_HZ 10000
-#define BACKLIGHT_STEP_USEC 10000 // 10ms per step.
+#define BACKLIGHT_STEP_USEC 20000 // 20ms per step.
 
 void backlight_init(void);
-void backlight_set(float new_duty, int fader_msec);
 void backlight_keepalive();
 bool backlight_active();
 
diff --git a/src/backlight.c b/src/backlight.c
index 1604929..0707558 100644
--- a/src/backlight.c
+++ b/src/backlight.c
@@ -4,8 +4,10 @@ static float backlight_duty;
 static float backlight_target_duty;
 static float backlight_step;
 
+
 static mgos_timer_id backlight_fader_timer_id = 0;
 static mgos_timer_id backlight_keepalive_timer_id = 0;
+static double backlight_last_keepalive;
 
 static void backlight_fader_cb(void *arg) {
   float new_duty = backlight_duty+backlight_step;
@@ -29,7 +31,7 @@ static void backlight_fader_cb(void *arg) {
 }
 
 
-void backlight_set(float new_duty, int fader_msec) {
+static void backlight_set(float new_duty, int fader_msec) {
   if (new_duty<0.0) backlight_target_duty=0.0;
   else if (new_duty>1.0) backlight_target_duty=1.0;
   else backlight_target_duty=new_duty;
@@ -37,6 +39,11 @@ void backlight_set(float new_duty, int fader_msec) {
   if (backlight_target_duty == backlight_duty)
     return;
 
+  if (backlight_fader_timer_id) {
+    LOG(LL_INFO, ("Cancelling current backlight_fader_timer due to new settings"));
+    mgos_clear_timer(backlight_fader_timer_id);
+    backlight_fader_timer_id=0;
+  }
   if (fader_msec == 0) {
     backlight_duty=backlight_target_duty;
     backlight_step=0.0;
@@ -44,24 +51,25 @@ void backlight_set(float new_duty, int fader_msec) {
     mgos_pwm_set(mgos_sys_config_get_app_backlight_pin(), BACKLIGHT_PWM_HZ, backlight_duty);
     return;
   }
-
   backlight_step = (backlight_target_duty - backlight_duty) / ((1000.0*fader_msec)/BACKLIGHT_STEP_USEC);
   LOG(LL_INFO, ("Changing backlight from %.2f to %.2f in %d msecs, steps of %.4f", backlight_duty, backlight_target_duty, fader_msec, backlight_step));
-  if (backlight_fader_timer_id)
-    mgos_clear_timer(backlight_fader_timer_id);
   backlight_fader_timer_id = mgos_set_timer(BACKLIGHT_STEP_USEC/1000, true, backlight_fader_cb, NULL);
 }
 
 static void backlight_keepalive_cb(void *arg) {
-  LOG(LL_INFO, ("Inactivity timeout of %d seconds reached, setting backlight off", mgos_sys_config_get_app_inactivity_timeout()));
-  backlight_set(0.0, 1000);
+  // We trigger a fade if:
+  // - current time is more than 3sec since our last keepalive
+  // - backlight_duty>0: the screen is on
+  // - backlight_fader_timer_id==0: we are not currenty fading
+  if ((mg_time() > backlight_last_keepalive + mgos_sys_config_get_app_inactivity_timeout()) && backlight_duty>0 && backlight_fader_timer_id==0) {
+    LOG(LL_INFO, ("Inactivity timeout of %d seconds reached, setting backlight off", mgos_sys_config_get_app_inactivity_timeout()));
+    backlight_set(0.0, 1500);
+  }
   (void) arg;
 }
 
 void backlight_keepalive() {
-  if (backlight_keepalive_timer_id)
-    mgos_clear_timer(backlight_keepalive_timer_id);
-  backlight_keepalive_timer_id = mgos_set_timer(mgos_sys_config_get_app_inactivity_timeout()*1000, false, backlight_keepalive_cb, NULL);
+  backlight_last_keepalive=mg_time();
   backlight_set(1.0, 0);
 }
 
@@ -72,5 +80,6 @@ bool backlight_active() {
 
 void backlight_init(void) {
   backlight_keepalive();
+  backlight_keepalive_timer_id = mgos_set_timer(1000, true, backlight_keepalive_cb, NULL);
   return;
 }