Retune neopixel timings on SAMD51. They were too slow.

tannewt · tannewt · commit b0dd645e2721 · 2018-08-07T16:58:37.000-07:00
Fixes #1083
diff --git a/ports/atmel-samd/common-hal/neopixel_write/__init__.c b/ports/atmel-samd/common-hal/neopixel_write/__init__.c
@@ -111,14 +111,14 @@ void common_hal_neopixel_write(const digitalio_digitalinout_obj_t* digitalinout,
         #ifdef SAMD51
         delay_cycles(3);
         #endif
-        if(p & bitMask) {
+        if((p & bitMask) != 0) {
             // This is the high delay unique to a one bit.
             // For the SK6812 its 0.3us
             #ifdef SAMD21
             asm("nop; nop; nop; nop; nop; nop; nop;");
             #endif
             #ifdef SAMD51
-            delay_cycles(11);
+            delay_cycles(3);
             #endif
             *clr = pinMask;
         } else {
@@ -140,7 +140,7 @@ void common_hal_neopixel_write(const digitalio_digitalinout_obj_t* digitalinout,
             asm("nop; nop; nop; nop; nop;");
             #endif
             #ifdef SAMD51
-            delay_cycles(20);
+            delay_cycles(4);
             #endif
         } else {
             if(ptr >= end) break;
@@ -151,7 +151,7 @@ void common_hal_neopixel_write(const digitalio_digitalinout_obj_t* digitalinout,
             // above operations take.
             // For the SK6812 its 0.6us +- 0.15us
             #ifdef SAMD51
-            delay_cycles(15);
+            delay_cycles(3);
             #endif
         }
     }
