From 85883da90c00eafdbb13d2aa76c8af19ec283468 Mon Sep 17 00:00:00 2001
From: Scott Lahteine <sourcetree@thinkyhead.com>
Date: Wed, 6 Apr 2016 17:31:18 -0700
Subject: [PATCH] Implement basic HOST_KEEPALIVE_INTERVAL

---
 Marlin/Marlin.h        | 4 ++++
 Marlin/Marlin_main.cpp | 3 ++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/Marlin/Marlin.h b/Marlin/Marlin.h
index 8fb742e0d..3c13fa216 100644
--- a/Marlin/Marlin.h
+++ b/Marlin/Marlin.h
@@ -325,6 +325,10 @@ extern bool axis_homed[3]; // axis[n].is_homed
   extern float zprobe_zoffset;
 #endif
 
+#if ENABLED(HOST_KEEPALIVE_FEATURE)
+  extern uint8_t host_keepalive_interval;
+#endif
+
 #if ENABLED(PREVENT_DANGEROUS_EXTRUDE)
   extern float extrude_min_temp;
 #endif
diff --git a/Marlin/Marlin_main.cpp b/Marlin/Marlin_main.cpp
index 8a3610d58..9a1e3ae6c 100644
--- a/Marlin/Marlin_main.cpp
+++ b/Marlin/Marlin_main.cpp
@@ -448,6 +448,7 @@ static bool send_ok[BUFSIZE];
 
   static MarlinBusyState busy_state = NOT_BUSY;
   static millis_t next_busy_signal_ms = -1;
+  uint8_t host_keepalive_interval = DEFAULT_KEEPALIVE_INTERVAL;
   #define KEEPALIVE_STATE(n) do{ busy_state = n; }while(0)
 #else
   #define host_keepalive() ;
@@ -2276,7 +2277,7 @@ void unknown_command_error() {
           break;
       }
     }
-    next_busy_signal_ms = ms + 10000UL; // "busy: ..." message every 10s
+    next_busy_signal_ms = host_keepalive_interval ? ms + 1000UL * host_keepalive_interval : -1;
   }
 
 #endif //HOST_KEEPALIVE_FEATURE