diff --git a/src/neopixel.c b/src/neopixel.c
index 6a5460c3..b799b516 100644
--- a/src/neopixel.c
+++ b/src/neopixel.c
@@ -28,12 +28,22 @@ command_config_neopixel(uint32_t *args)
 DECL_COMMAND(command_config_neopixel, "config_neopixel oid=%c pin=%u");
 #endif
 
-uint32_t
+static uint32_t
 timer_from_ns(uint32_t ns)
 {
     return timer_from_us(ns * 1000) / 1000000;
 }
 
+// The WS2812 uses a bit-banging protocol where each bit is
+// transmitted as a gpio high pulse of variable length.  The various
+// specs are unclear, but it is believed the timing requirements are:
+// - A zero bit must have a high pulse less than 500ns.
+// - A one bit must have a high pulse longer than 650ns.
+// - The total bit time (gpio high to following gpio high) must not
+//   exceed ~5000ns. The average bit time must be at least 1250ns.
+// - The specs generally indicate a minimum high pulse and low pulse
+//   of 200ns, but the actual requirement might be smaller.
+
 static int
 send_data(struct neopixel_s *n, uint8_t *data, uint_fast8_t data_len)
 {
@@ -51,47 +61,55 @@ send_data(struct neopixel_s *n, uint8_t *data, uint_fast8_t data_len)
         uint_fast8_t bits = 8;
         while (bits--) {
             // Calculate pulse duration
-            uint32_t on, off;
-            if (byte & 0x80) {
-                on = timer_from_ns(700 - 150);
-                off = timer_from_ns(600 - 150);
-            } else {
-                on = timer_from_ns(350 - 150);
-                off = timer_from_ns(800 - 150);
-            }
-            byte <<= 1;
+            uint32_t on;
+            if (byte & 0x80)
+                on = timer_from_ns(650);
+            else
+                on = timer_from_ns(200);
 
             // Set output high
             do {
                 irq_poll();
                 cur = timer_read_time();
             } while (timer_is_before(cur, min_wait_time));
+            uint32_t off_end_time = cur;
             gpio_out_write(pin, 1);
             uint32_t on_start_time = timer_read_time();
-            if (timer_is_before(max_wait_time, on_start_time))
-                goto fail;
             min_wait_time = on_start_time + on;
-            max_wait_time = cur + on + timer_from_ns(300);
 
             // Set output low
             do {
                 irq_poll();
                 cur = timer_read_time();
             } while (timer_is_before(cur, min_wait_time));
+            uint32_t on_end_time = cur;
             gpio_out_write(pin, 0);
-            uint32_t off_start_time = timer_read_time();
-            if (timer_is_before(max_wait_time, off_start_time))
+            uint32_t off_start_time = cur = timer_read_time();
+            min_wait_time = on_start_time + timer_from_ns(1250);
+
+            // Check for faults
+            if (byte & 0x80) {
+                // Make sure off for at least 200ns
+                uint32_t min_off = off_start_time + timer_from_ns(200);
+                if (timer_is_before(min_wait_time, min_off))
+                    min_wait_time = min_off;
+            } else {
+                // Make sure short on duration was no more than 500ns
+                uint32_t max_off = off_end_time + timer_from_ns(500);
+                if (timer_is_before(max_off, off_start_time))
+                    goto fail;
+            }
+            byte <<= 1;
+            if (timer_is_before(max_wait_time, on_start_time))
                 goto fail;
-            min_wait_time = off_start_time + off;
-            max_wait_time = cur + off + timer_from_ns(300);
+            max_wait_time = on_end_time + timer_from_us(4);
         }
     }
-    n->last_req_time = timer_read_time();
+    n->last_req_time = cur;
     return 0;
 fail:
     // A hardware irq messed up the transmission - report a failure
-    gpio_out_write(pin, 0);
-    n->last_req_time = timer_read_time();
+    n->last_req_time = cur;
     return -1;
 }