using 1.1v Vref on the Arduino analog to digital converter for better precision

serial/essai.sh

@@ -7,17 +7,17 @@ TMPFILE="/tmp/dd2data"
 IMAGE="graphe.png"
 NB_READ=5000
 
-./t -v -n ${NB_READ} -d ${DEVICE} | tee -a ${DATAFILE}
+./t -vv -n ${NB_READ} -d ${DEVICE} | tee -a ${DATAFILE}
 
 gnuplot << __EOC__
-set term png 	size 3200,512
+set term png 	size 3200,640
 set output 	"${IMAGE}"
 set grid
 set title	"Temperature dans le Double Dragon 2"
 set xdata 	time
 set timefmt 	"%s"
 set format x 	"%a, %H:%M:%S"
-set yrange [ 5.0 : 30.0]
+set yrange [ 0.0 : 30.0]
 plot	"${DATAFILE}" using 1:2 title " foo" with lines, \
 	"${DATAFILE}" using 1:3 title " bar" with lines, \
 	"${DATAFILE}" using 1:4 title "quux" with lines, \

serial/funcs.c

@@ -45,12 +45,18 @@ return value;
 /*
  *   this fonction is specific to the LM35 thermo-sensor
  *   connected to a ADC pin of an Arduino Mega
+ *
+ *	WARNING !
+ *   this function _must_ be modofied if you change the
+ *   Vref of the Analog to Digital converter on the
+ *   Arduino !
+ *
  */
 int values2temperature(float array[4])
 {
 int	foo;
 for (foo=0; foo<4; foo++) {
- 	array[foo] *= (5.0 / 1023.0 * 100.0);
+ 	array[foo] *= (1.1 / 1023.0 * 100.0);
 	}
 return 0;
 }

serial/t.c

@@ -29,9 +29,9 @@ float		datas[4];
 for (count=0; count<iters; count++) {
 	foo = getline_to(sfd, ligne, 100, 0);
 	//
-	if (verbosity > 1) {
-		fprintf(stderr, "getline #%d on %d -> %d\n",
-					count, iters, foo);
+	if (verbosity) {
+		/* fprintf(stderr, "getline #%d on %d -> %d\n",
+					count, iters, foo); */
 		fprintf(stderr, "%s\n", ligne);
 		}
 	foo = parse4values(ligne, 'T', datas);

simulator/rdtemp/rdtemp.ino

@@ -4,7 +4,7 @@
 /* -------------------------------------------------- */
 
 #define NBVAL   4
-#define DELAI   10000
+#define DELAI   12000
 
 int   values[NBVAL];
 
@@ -13,7 +13,14 @@ void setup() {
   Serial.begin(9600);
   pinMode(LED_BUILTIN, OUTPUT);
   Serial.print("\n");
-  delay(2000);
+  /* XXX */
+  /*  changing the voltage reference of the ADC
+   *  greatly increase the prcision on the limited
+   *  range of our temperatures.
+   */
+  analogReference(INTERNAL1V1); // Pour Arduino Mega2560
+  
+  delay(1000);
 }
 /* -------------------------------------------------- */
 void updatevalues(void)
@@ -21,7 +28,7 @@ void updatevalues(void)
   int foo;
   for (foo=0; foo<NBVAL; foo++) {
     values[foo] = analogRead(A0);
-    delay(500);
+    delay(200);
    }
 }
 /* -------------------------------------------------- */