Debounce digital inputs

r1387 | dcl | 2007-01-09 11:15:02 +1100 (Tue, 09 Jan 2007) | 2 lines

site_ansto/hardsup/Digital/device.c

@@ -43,6 +43,7 @@ void device_write(DEVICE *device, int n, const char* tp)
   unsigned long value;
 
   value = strtol(tp, NULL, 16);
+  device->out_value = value;
   hware_write(device->private_data, value);
   return;
 }
@@ -54,6 +55,13 @@ void device_print(DEVICE* device, FILE* fd)
       device->value);
   fflush(fd);
 }
+/*
+ * Finalise the current sample and move on to the next
+ */
+void device_sample(DEVICE* device)
+{
+  device->sample_timer = device->current_time;
+}
 
 void device_report(DEVICE* device)
 {
@@ -93,16 +101,18 @@ int device_init(DEVICE** cpp, char* name)
   *cpp = device;
   memset(device, 0, sizeof(DEVICE));
   strncpy(device->name, name, sizeof(device->name));
-  device->params.poll_period = 1000;        /* milliseconds between polls */
+  device->params.poll_period = 100;        /* milliseconds between polls */
-  device->params.sample_period = 10;       /* polls between sample calcs */
+  device->params.sample_period = 5;       /* polls between sample calcs */
-  device->params.report_period = 3;      /* samples between reports */
+  device->params.report_period = 10;      /* samples between reports */
   device->state = device_stopped;
   struct timeval now;
   gettimeofday(&now, NULL);
   device->current_time = now;
   device->previous_time = now;
+  device->sample_timer = now;
   device->report_timer = now;
   HWARE_TEST(hware_ctor(name, &device->private_data));
+  device_sample(device);
   return 0;
 Error:
   hware_errmsg(errBuff, sizeof(errBuff));
@@ -152,20 +162,35 @@ int device_poll(DEVICE* device)
   dbg_printf(0, "device_poll = 0x%06X @ %s\n",
       current_local_value,
       make_timestamp(&device->current_time));
-  if (current_local_value != device->value)
+
+  if ((current_local_value != device->value)
+      || (current_local_value != device->new_value))
+  {
+    if (current_local_value != device->new_value)
+    {
+      device->new_value = current_local_value;
+      device->new_count = device->params.sample_period;
+    }
+    else if (--device->new_count <= 0)
     {
       char str[100];
       snprintf(str, sizeof(str), "changed 0x%06X 0x%06X",
           current_local_value,
           device->value);
       device_event(device, str);
-  }
       device->value = current_local_value;
+    }
+  }
+  /* check if it is time to roll the sample */
+  if (device_time_to_next_sample(device) <= 0)
+  {
     /* check if it is time to roll the report */
     if (device_time_to_next_report(device) <= 0)
     {
       device_report(device);
     }
+    device_sample(device);
+  }
 
   return error;
 Error:
@@ -213,3 +238,21 @@ double device_time_to_next_report(DEVICE* device)
   timeout = timeout - timeofday % timeout;
   return 0.001 * timeout;
 }
+
+double device_time_to_next_sample(DEVICE* device)
+{
+  uint64 last_sample;
+  uint64 timeofday;
+  int timeout;
+  struct timeval now;
+  now = device->current_time;
+  last_sample = 1000 * (uint64) device->sample_timer.tv_sec;
+  last_sample += (uint64) device->sample_timer.tv_usec / 1000;
+  timeofday = 1000 * (uint64) now.tv_sec;
+  timeofday += (uint64) now.tv_usec / 1000;
+  timeout = device->params.poll_period * device->params.sample_period;
+  if ((last_sample / timeout) != (timeofday / timeout))
+    return 0.0;
+  timeout = timeout - timeofday % timeout;
+  return 0.001 * timeout;
+}

site_ansto/hardsup/Digital/device.h

@@ -28,12 +28,20 @@ typedef struct device_t
   struct timeval    current_time;
   /** time of last read */
   struct timeval    previous_time;
+  /** time of next sample closure */
+  struct timeval    sample_timer;
   /** time of next report generation */
   struct timeval    report_timer;
   /** number of polls */
   int               poll_counter;
+  /** output value */
+  unsigned int      out_value;
   /** physical device value */
   unsigned int      value;
+  /** tentative new value */
+  unsigned int      new_value;
+  /** debounce counter */
+  int               new_count;
   /** Control parameters */
   PARAMETERS        params;
   struct device_private_t* private_data;