Working version!

macie.py

+import serial, time
+import serial.tools.list_ports
+
+
+class macie:
+    def __init__(self, read_timeout=3, baud_rate=115200):
+        self.device = None
+        for port in serial.tools.list_ports.grep("arduino"):
+            device = serial.Serial(port.device, 115200, timeout=3)
+            time.sleep(2)  # Give the device a chance!
+            first_line =  device.readline()
+            if first_line == b'<macie is ready to work>\r\n':
+                self.device = device
+                break
+            else:
+                device.close()
+
+        if self.device is None:
+            raise RuntimeError("Could not connect to a macie!")
+
+        self.device.readlines()  # Make sure to empty read buffer
+    
+    def check_result(self):
+        return_value = self.device.read()
+        if return_value == b'':
+            print('Warning: macie timed out.')
+        elif return_value != b'\0':
+            raise RuntimeError("Command timeout: Unknown problem in macie!")
+
+    def trigger_led(self, led_index):
+        self.device.write(str(led_index).encode() + b'\n')
+        self.check_result()
+
+    def flood_light(self, leds="w"):
+        if leds == "w" or leds == "W":
+            self.device.write(b'f')
+        if leds == "rgbw" or leds == "RGBW":
+            self.device.write(b'F')
+        self.check_result()
+
+    def dark(self):
+        self.device.write(b'b')
+        self.check_result()
+
+mace = macie()
+
+for i in range(15):
+    mace.trigger_led(i)
+
+mace.flood_light()
+mace.flood_light("RGBW")
+mace.dark()

neopx/neopx.ino

+#include <Adafruit_NeoPixel.h>
+
+#define LED_PIN    7
+#define LED_COUNT 15
+
+Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_RBGW + NEO_KHZ800);
+
+uint32_t all_white = Adafruit_NeoPixel::Color(255, 255, 255, 255);
+uint32_t white = Adafruit_NeoPixel::Color(0, 0, 0, 255);
+
+
+void setup() {
+  Serial.begin(115200); // set up Serial library at 9600 bps
+    
+  strip.begin();
+  strip.clear();
+  strip.show();
+  
+  Serial.println("<macie is ready to work>");
+}
+
+void loop() {
+  static const uint8_t buffer_size = 3;
+  static char data_buffer[buffer_size];
+  static uint8_t buffer_idx = 0;
+  static bool reading_data = true;
+  
+  if(Serial.available() > 0 && reading_data) {
+    char next_data = Serial.read();
+
+    // single character commands
+    if (buffer_idx == 0 && next_data == 'b') {
+      strip.clear();
+      strip.show();
+      Serial.write('\0');
+      return;
+    }
+    if (buffer_idx == 0 && next_data == 'B') {
+      strip.clear();
+      strip.show();
+      Serial.write('\0');
+      return;
+    }
+    if (buffer_idx == 0 && next_data == 'F') {
+      strip.fill(all_white);
+      strip.show();
+      return;
+    }
+    if (buffer_idx == 0 && next_data == 'f') {
+      strip.fill(white);
+      strip.show();
+      Serial.write('\0');
+      return;
+    }
+
+    // multi character commands
+    static char eol = '\n';
+    if (next_data != eol) {
+      data_buffer[buffer_idx] = next_data;
+      buffer_idx++;
+      if (buffer_idx >= buffer_size)
+        buffer_idx = buffer_size - 1;  // Just reuse the last char
+    } else {  // End of line---stop reading!
+      data_buffer[buffer_idx] = '\0';
+      buffer_idx = 0;
+      reading_data = false;
+    }
+
+    
+    if (!reading_data) {
+      reading_data = true;
+      
+      if (data_buffer[0] < '0' || data_buffer[0] > '9')  // Non-digit
+        return;
+      int x = data_buffer[0] - '0';
+
+      if (data_buffer[1] != '\0') {  // multi-digit
+        if (data_buffer[1] < '0' || data_buffer[1] > '9')  // Non-digit
+          return;
+        x *= 10;
+        x += data_buffer[1] - '0';
+        
+        if (data_buffer[2] != '\0') {  // multi-digit
+          if (data_buffer[2] < '0' || data_buffer[2] > '9')  // Non-digit
+            return;
+          x *= 10;
+          x += data_buffer[2] - '0';
+        }
+        if (data_buffer[3] != '\0')
+          return;
+      }
+
+      strip.clear();
+      strip.setPixelColor(x, 0, 0, 0, 255);
+      strip.show();
+
+      Serial.write('\0');
+    }
+  }
+}