add optional support for WS2812 RGB LED, fixes #106

specific indexes in the LED color time sequence are used for:

- dark separator indicates "start of sequence"
  (also used for LED init and re-init)

- color according to indications (3bits encoded via RGB color)
  (can be extended to show up to 32 indication bits)
  (dark if there is nothing to indicate)

- white separator indicates "start of radiation display"
  (also works as LED test, white = R on + G on + B on)

- color according to radiation (repeated, displayed most of the time)
  dark (unusually low / 0)
  green (normal)
  yellow (more than normal)
  red (much more than normal)

multigeiger/multigeiger.ino

@@ -83,6 +83,8 @@
 #include <Adafruit_Sensor.h>
 #include <Adafruit_BME280.h>
 
+// for RGB LED
+#include "status_led.h"
 
 // Check if a CPU (board) with LoRa is selected. If not, deactivate SEND2LORA.
 #if !((CPU==LORA) || (CPU==STICK))
@@ -553,6 +555,9 @@ void loop() {
 
     Dose_Rate = Count_Rate * GMC_factor_uSvph;                          // ... and dose rate
 
+    // indicate status on RGB LED (if any)
+    indicate(Dose_Rate, I_TEST);
+
     // calculate the radiation over the complete time from start
     accumulated_Count_Rate = 0.0;
     if (accumulated_time != 0) {

multigeiger/status_led.cpp

@@ -0,0 +1,107 @@
+// show status indication via WS2812 RGB LED
+
+#include "userdefines.h"
+
+#if STATUS_LED==1 // we have a WS2812 RGB LED!
+
+#include <NeoPixelBus.h>
+
+#include "status_led.h"
+
+#define PIXEL_COUNT 1
+#define PIXEL_PIN 25
+
+RgbColor red(255, 0, 0);
+RgbColor green(0, 255, 0);
+RgbColor blue(0, 0, 255);
+RgbColor yellow(255, 255, 0);
+RgbColor white(255, 255, 255);
+RgbColor black(0, 0, 0);
+
+static NeoPixelBus<NeoRgbFeature, Neo800KbpsMethod> LEDs(PIXEL_COUNT, PIXEL_PIN);
+
+static RgbColor last_col = black;
+
+static void set_LED(RgbColor col) {
+  if (col == last_col)
+    return;  // nothing to change
+
+  LEDs.SetPixelColor(0, col);  // only 1 LED at index 0
+  LEDs.Show();
+  last_col = col;
+}
+
+static void init_LED(void) {
+  LEDs.Begin();  // all LEDs off
+  LEDs.Show();
+  last_col = black;  // consistency sw state == hw state
+}
+
+static void compute_color(unsigned int indication,
+                          unsigned int mask_r, unsigned int mask_g, unsigned int mask_b,
+                          RgbColor *color) {
+  // assign to *color depending on whether the r/g/b masked bits are set in the indication value
+  *color = RgbColor((indication & mask_r) ? 255 : 0,
+                    (indication & mask_g) ? 255 : 0,
+                    (indication & mask_b) ? 255 : 0)
+}
+
+#define IDX_W 2
+#define CSL 30
+
+void indicate(float radiation, unsigned int indication) {
+  // radiation [uSv/h] given to set the primary color R that is shown most of the time
+  // indication: 32 bit flags to indicate additional stuff, see status_led.h.
+  //
+  // this code will generate a time sequence of LED colors:
+  // index     color
+  // ------------------------------------------------------ 
+  // 0         dark (LED init)
+  // 1         indication color 1
+  // ...       reserved for more indications
+  // IDX_W     white (LED test)
+  // ...+1     radiation color
+  // ...       radiation color
+  // CSL-1     radiation color
+
+  RgbColor col;
+  static int index = 0;  // index counting modulo COLOR_SEQUENCE_LENGTH
+
+  switch (index) {
+  case 0:  // show a fixed dark separator after LED init
+    init_LED();  // (re-)init the LED
+    col = black;
+    break;
+  case 1:
+    // indication color 1:    R             G       B
+    compute_color(indication, I_CONN_ERROR, I_TEST, I_HV_ERROR, &col);
+    break;
+  case IDX_W:  // show a fixed white separator and LED test
+    col = white;
+    break;
+  default:  // show radiation color
+    if (radiation > 1.0) {
+      col = red;
+    } else if (radiation > 0.2) {
+      col = yellow;
+    } else if (radiation > 0.01) {
+      col = green;
+    } else {
+      col = black;
+    }
+  }
+
+  set_LED(col);
+
+  if (++index == CSL)
+    index = 0;
+}
+
+#else // no STATUS_LED
+
+void indicate(float radiation, unsigned int indication) {
+  // do nothing
+}
+
+#endif // STATUS_LED
+

multigeiger/status_led.h

@@ -0,0 +1,15 @@
+// show status indication via WS2812 RGB LED
+
+// indication value used to reset indications to "all off"
+#define I_RESET 0
+// indication value used to mask no bit, e.g. in compute_color
+#define I_NONE 0
+
+// indications, values are 32bit bit masks, valid values are 2^N
+#define I_TEST 1  // reserved to test the indication code
+#define I_HV_ERROR 2  // there is a problem with high voltage generation
+#define I_CONN_ERROR 4  // there is a problem with the network connection
+
+// indicate radiation and special indications via a color time sequence.
+// you should call this in regular time intervals [e.g. 1s].
+void indicate(float radiation, unsigned int indication);

multigeiger/userdefines-example.h

@@ -61,6 +61,9 @@
 // Note: The TTN configuration needs to be done in lorawan.cpp (starting at line 65).
 #define SEND2LORA 0
 
+// 0: no RGB status LED, 1: WS2812B status LED
+#define STATUS_LED 1
+
 // *********************************************************************************
 // END of user changeable parameters.  Do not edit beyond this point!
 // *********************************************************************************

platformio-example.ini

@@ -44,4 +44,5 @@ lib_deps=
   Adafruit BME280 Library
   Adafruit Unified Sensor
   IotWebConf
+  NeoPixelBus