Converted SilenceTimer on MS/TP datalink to be a function so that it can be atomic on 8-bit microcontrollers.

bacnet-stack/ports/atmega168/main.c

@@ -75,7 +75,7 @@ void init(void)
     RS485_Set_Baud_Rate(38400);
 
     /* Configure Timer0 for millisecond timer */
-    timer_initialize();
+    Timer_Initialize();
 
     /* Enable global interrupts */
     sei();
@@ -86,9 +86,6 @@ void task_milliseconds(void)
     while (Timer_Milliseconds) {
         Timer_Milliseconds--;
         /* add other millisecond timer tasks here */
-#if defined(BACDL_MSTP)
-        dlmstp_millisecond_timer();
-#endif
     }
 }
 

bacnet-stack/ports/atmega168/rs485.c

@@ -128,7 +128,7 @@ void RS485_Send_Frame(
         if (!turnaround_time) {
             turnaround_time = 1;
         }
-        while (mstp_port->SilenceTimer < turnaround_time) {
+        while (mstp_port->SilenceTimer() < turnaround_time) {
             /* do nothing - wait for timer to increment */
         };
     }
@@ -146,7 +146,7 @@ void RS485_Send_Frame(
     }
     /* per MSTP spec */
     if (mstp_port) {
-        mstp_port->SilenceTimer = 0;
+        mstp_port->SilenceTimerReset();
     }
 
     return;

bacnet-stack/ports/atmega168/timer.c

@@ -37,9 +37,11 @@
 #define TIMER_COUNT (0xFF-TIMER_TICKS)
 /* Global variable millisecond timer - used by main.c for timers task */
 volatile uint8_t Timer_Milliseconds = 0;
+/* MS/TP Silence Timer */
+static volatile uint16_t SilenceTime;
 
 /* Configure the Timer */
-void timer_initialize(void)
+void Timer_Initialize(void)
 {
     /* Normal Operation */
     TCCR1A = 0;
@@ -76,4 +78,31 @@ ISR(TIMER0_OVF_vect)
     /* Update the global timer */
     if (Timer_Milliseconds < 0xFF)
        Timer_Milliseconds++;
+    if (SilenceTime < 0xFFFF)
+        SilenceTime++;
+}
+
+/* Public access to the Silence Timer */
+uint16_t Timer_Silence(void)
+{
+    uint16_t timer;
+    uint8_t sreg;
+
+    sreg = SREG;
+    cli();
+    timer = SilenceTime;
+    SREG = sreg;
+
+    return timer;
+}
+
+/* Public reset of the Silence Timer */
+void Timer_Silence_Reset(void)
+{
+    uint8_t sreg;
+
+    sreg = SREG;
+    cli();
+    SilenceTime = 0;
+    SREG = sreg;
 }

bacnet-stack/ports/atmega168/timer.h

@@ -27,6 +27,16 @@
 
 extern volatile uint8_t Timer_Milliseconds;
 
-void timer_initialize(void);
+#ifdef __cplusplus
+extern "C" {
+#endif                          /* __cplusplus */
+
+void Timer_Initialize(void);
+uint16_t Timer_Silence(void);
+void Timer_Silence_Reset(void);
+
+#ifdef __cplusplus
+}
+#endif                          /* __cplusplus */
 
 #endif