diff --git a/mini-beieli-node.ino b/mini-beieli-node.ino index b8d90f9..0773207 100644 --- a/mini-beieli-node.ino +++ b/mini-beieli-node.ino @@ -536,13 +536,52 @@ void DoDeepSleep(uint32_t sleep_time) } } +//Following functions are based on "https://github.com/dndubins/QuickStats", by David Dubins + +long median(long samples[], int m) //calculate the median +{ + //First bubble sort the values: https://en.wikipedia.org/wiki/Bubble_sort + long sorted[m]; // Define and initialize sorted array. + long temp = 0; // Temporary float for swapping elements + + for (int i = 0; i < m; i++) { + sorted[i] = samples[i]; + } + bubbleSort(sorted, m); // Sort the values + + if (bitRead(m, 0) == 1) { //If the last bit of a number is 1, it's odd. This is equivalent to "TRUE". Also use if m%2!=0. + return sorted[m / 2]; //If the number of data points is odd, return middle number. + } else { + return (sorted[(m / 2) - 1] + sorted[m / 2]) / 2; //If the number of data points is even, return avg of the middle two numbers. + } +} + +void bubbleSort(long A[], int len) { + unsigned long newn; + unsigned long n = len; + long temp = 0; + do { + newn = 1; + for (int p = 1; p < len; p++) { + if (A[p - 1] > A[p]) { + temp = A[p]; //swap places in array + A[p] = A[p - 1]; + A[p - 1] = temp; + newn = p; + } //end if + } //end for + n = newn; + } while (n > 1); +} + long my_read_average(byte gain, byte times) { - // highest and lowest value will be ignored - long sum = 0; - long v = 0; - long L = 2147483647; - long H = -2147483648; long res; + int const num_scale_readings = 100; //number of instantaneous scale readings to calculate the median + + // we use the median, not the average, see https://community.particle.io/t/boron-gpio-provides-less-current-than-electrons-gpio/46647/13 + long readings[num_scale_readings]; // create arry to hold readings + + // highest and lowest value will be ignored if (config_data.debug_level > 0) { gCatena.SafePrintf("%010d - my_read_average, measurements: ", millis()); } @@ -551,22 +590,14 @@ long my_read_average(byte gain, byte times) { // we wait 400ms (settling time according HX711 datasheet @ 10 SPS delay(400); - for (byte i = 0; i < times; i++) { - // we wait 400ms (settling time according HX711 datasheet @ 10 SPS) - v = LoadCell.read(); - - if (L > v) L = v; // find lowest value - if (H < v) H = v; // find highest value - sum += v; - if (config_data.debug_level > 0) { - gCatena.SafePrintf("%d ", v); - } - gCatena.poll(); - delay(WAITTIMELOADSAMPLES); + for (int i = 0; i < num_scale_readings; i++) { + readings[i] = LoadCell.read(); // fill the array with instantaneous readings from the scale } - res = (sum - L - H) / (times - 2); + + res = median(readings, num_scale_readings); //calculate median + if (config_data.debug_level > 0) { - gCatena.SafePrintf("; average (without highest [%d] and lowest [%d] value): %d\n", H, L, res); + gCatena.SafePrintf("; median of %d samples: %d\n", num_scale_readings, res); } return res; diff --git a/mini_beieli_node.h b/mini_beieli_node.h index f12866a..1b09912 100644 --- a/mini_beieli_node.h +++ b/mini_beieli_node.h @@ -55,10 +55,7 @@ enum { | \****************************************************************************/ -static const int32_t fwVersion = 20200109; - -// wait between samples in milliseconds -const int WAITTIMELOADSAMPLES = 100; +static const int32_t fwVersion = 20200113; static const byte INIT_PACKAGE_INTERVAL = 100; // send an init package every 100 packages; static const byte MAX_VALUES_TO_SEND = 8;