Diff: WS2812.cpp

Revision:

15:331e139672b5

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WS2812.cpp	Thu Dec 05 15:12:47 2013 +0000
@@ -0,0 +1,82 @@
+// 800 KHz WS2812 driver, kinda.
+//
+// Parameterized and modified to use soft SPI.
+// Jas Strong <jasmine@electronpusher.org>
+// Modified to use hard SPI by Ned Konz <ned@bike-nomad.com>
+/*****************************************************************************/
+
+#include "LedStrip.h"
+#include "WS2812.h"
+
+WS2812::WS2812(int n, PinName mosi, PinName sclk) :
+    LedStrip(n),
+    spi(mosi, NC, sclk)
+{
+#ifdef TARGET_KL25Z
+    spi.format(8, 3);
+#else
+    spi.format(16, 3);
+#endif
+    spi.frequency(800e3 * 16);  // 12.8 MHz => 800KHz bit rate
+}
+
+/*
+ *  These chips use a one-wire protocol based on a sort of NRZ signalling- jas.
+ */
+
+inline void WS2812::writebit(bool bit)
+{
+    if (bit) {
+#ifdef TARGET_KL25Z
+        spi.write(0xff);    // 8 high
+        spi.write(0x00);    // 8 low
+#else
+        spi.write(0xff00);
+#endif
+    } else {
+#ifdef TARGET_KL25Z
+        spi.write(0xe0);    // 3 high, 5 low
+        spi.write(0x00);    // +8 low
+#else
+        spi.write(0xe000);
+#endif
+    }
+}
+
+void WS2812::write(uint8_t byte)
+{
+    writebit(byte & 0x80);
+    writebit(byte & 0x40);
+    writebit(byte & 0x20);
+    writebit(byte & 0x10);
+    writebit(byte & 0x08);
+    writebit(byte & 0x04);
+    writebit(byte & 0x02);
+    writebit(byte & 0x01);
+}
+
+void WS2812::begin(void)
+{
+    blank();
+    show();
+}
+
+void WS2812::blank(void)
+{
+    memset(pixels, 0x00, numPixelBytes());
+}
+
+void WS2812::show(void)
+{
+    uint16_t i, nl3 = numPixelBytes(); // 3 bytes per LED
+    while (guardtime.read_us() < 50)
+        /* spin */;
+    __disable_irq();
+    for (i=0; i<nl3; i++ ) {
+        write(pixels[i]);
+    }
+    __enable_irq();
+    guardtime.reset();
+}
+
+