avr: add a ms timestamp to a pls message for pulse inputs

mote/v1/avr/main.c

@@ -43,6 +43,8 @@ volatile struct state aux[4] = {{false, false, START, 0}, {false, false, START,
 volatile struct sensor EEMEM EEPROM_measurements[4] = {{SENSOR0, START}, {SENSOR1, START}, {SENSOR2, START}, {SENSOR3, START}};
 volatile struct sensor measurements[4];
 
+volatile struct time_struct time = {false, 0};
+
 volatile uint8_t muxn = 0;
 volatile uint16_t timer = 0;
 
@@ -50,12 +52,14 @@ volatile uint16_t timer = 0;
 ISR(INT0_vect) {
   measurements[2].value++;
   aux[2].pulse = true;
+  aux[2].time  = time.ms;
 }
 
 // interrupt service routine for INT1
 ISR(INT1_vect) {
   measurements[3].value++;
   aux[3].pulse = true;
+  aux[3].time  = time.ms;
 }
 
 // interrupt service routine for PCI2 (PCINT20)
@@ -67,6 +71,7 @@ ISR(PCINT2_vect) {
   else {
     measurements[4].value++;
     aux[4].pulse = true;
+    aux[4].time  = time.ms;
     aux[4].toggle = false;
   }
 }
@@ -104,6 +109,11 @@ ISR(TIMER2_COMPA_vect) {
   if (!(muxn &= 0x1)) timer++;
   if (timer > SECOND) timer = 0;
 
+  // We have timer interrupts occcuring at a frequency of 1250Hz.
+  // In order to map this to 1000Hz (=ms) we have to skip every fifth interrupt.
+  if (!time.skip) time.ms++;
+  time.skip = (((time.ms & 0x3) == 3) && !time.skip) ? true : false;
+
   ADMUX &= 0xF8;
   ADMUX |= muxn;
   // start a new ADC conversion
@@ -260,13 +270,14 @@ void setup()
 
 void send(uint8_t msg_type, const struct sensor *measurement, const struct state *aux)
 {
-  uint8_t i = 46;
+  uint8_t i;
-  char message[49];
   uint32_t value = 0;
-
+  uint32_t ms = 0;
   int32_t rest;
   uint8_t pulse_count;
 
+  char message[60];
+
   switch (msg_type) {
   case PULSE:
     // blink the green LED
@@ -276,6 +287,7 @@ void send(uint8_t msg_type, const struct sensor *measurement, const struct state
 
     cli();
     value = measurement->value;
+    ms = aux->time;
     sei();
  
     strcpy(message, "pls ");
@@ -302,10 +314,19 @@ void send(uint8_t msg_type, const struct sensor *measurement, const struct state
   strcpy(&message[4], measurement->id);
   strcpy(&message[36], ":0000000000\n");
 
+  i = 46;
   do {                                // generate digits in reverse order
     message[i--] = '0' + value % 10;  // get next digit
   } while ((value /= 10) > 0);        // delete it
 
+  if ((msg_type == PULSE) && ms) {
+    strcpy(&message[47], ":0000000000\n");
+    i = 57;
+    do {                                // generate digits in reverse order
+      message[i--] = '0' + ms % 10;     // get next digit
+    } while ((ms /= 10) > 0);           // delete it
+  }
+
   printString(message);
 }
 

mote/v1/avr/main.h

@@ -88,6 +88,11 @@ asm volatile ( \
 )
 
 // datastructures
+struct time_struct {
+  boolean skip;
+  uint32_t ms; 
+};
+
 struct state {
   boolean  pulse;
   boolean  toggle;
@@ -99,6 +104,8 @@ struct state {
   uint32_t nano_end;
   uint8_t  pulse_count;
   uint8_t  pulse_count_final;
+
+  uint32_t time;
 };
 
 struct sensor {