Initial commit

ws2812/ws2812_m0_16m.go

@@ -0,0 +1,40 @@
+// +build nrf51
+
+package ws2812
+
+import (
+	"device/arm"
+)
+
+// Send a single byte using the WS2812 protocol.
+func (p WS2812) WriteByte(c byte) {
+	// For the Cortex-M0 at 16MHz
+	portSet, maskSet := p.Pin.PortMaskSet()
+	portClear, maskClear := p.Pin.PortMaskClear()
+
+	value := uint32(c) << 24
+	arm.AsmFull(`
+	send_bit:
+		str   {maskSet}, {portSet}
+		lsls  {value}, #1
+		bcs.n skip_store
+		str   {maskClear}, {portClear}
+	skip_store:
+		nop
+		nop
+		nop
+		nop
+		nop
+		nop
+		str   {maskClear}, {portClear}
+		subs  {i}, #1
+		bne.n send_bit
+	`, map[string]interface{}{
+		"value":     value,
+		"i":         8,
+		"maskSet":   maskSet,
+		"portSet":   portSet,
+		"maskClear": maskClear,
+		"portClear": portClear,
+	})
+}