Diff: LPD8806.cpp

Revision:

0:12e734116fea

Child:

1:6ebd3ac910b6

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/LPD8806.cpp	Fri Dec 16 03:16:50 2011 +0000
@@ -0,0 +1,85 @@
+// Mbed library to control LPD8806-based RGB LED Strips
+// (c) 2011 Jelmer Tiete
+// This library is ported from the Arduino implementation of Adafruit Industries
+// found at: http://github.com/adafruit/LPD8806
+// and their strips: http://www.adafruit.com/products/306
+// Released under the MIT License: http://mbed.org/license/mit
+
+/*****************************************************************************/
+
+#include "LPD8806.h"
+
+//Define SPI pins
+SPI spi(p5, p6, p7); // mosi, miso, sclk
+//SPI spi(p11, p12, p13); // mosi, miso, sclk
+
+LPD8806::LPD8806(uint16_t n) {
+    // Allocate 3 bytes per pixel:
+    if (NULL != (pixels = (uint8_t *)malloc(numLEDs * 3))) {
+        memset(pixels, 0x80, numLEDs * 3); // Init to RGB 'off' state
+        numLEDs     = n;
+    }
+}
+
+void LPD8806::begin(void) {
+
+    // Setup the spi for 8 bit data, low steady state clock,
+    // first edge capture, with a 2MHz clock rate
+    spi.format(8,0);
+    spi.frequency(2000000);
+
+    // Issue initial latch to 'wake up' strip (latch length varies w/numLEDs)
+    writezeros(3 * ((numLEDs + 63) / 64));
+}
+
+uint16_t LPD8806::numPixels(void) {
+    return numLEDs;
+}
+
+void LPD8806::writezeros(uint16_t n) {
+    while (n--) spi.write(0x00);
+}
+
+// This is how data is pushed to the strip.  Unfortunately, the company
+// that makes the chip didnt release the  protocol document or you need
+// to sign an NDA or something stupid like that, but we reverse engineered
+// this from a strip controller and it seems to work very nicely!
+void LPD8806::show(void) {
+    uint16_t i, nl3 = numLEDs * 3; // 3 bytes per LED
+
+    for (i=0; i<nl3; i++ ) {
+        spi.write(pixels[i]);
+    }
+
+    // Write latch at end of data; latch length varies with number of LEDs
+    writezeros(3 * ((numLEDs + 63) / 64));
+
+    // We need to have a delay here, a few ms seems to do the job
+    // shorter may be OK as well - need to experiment :(
+// wait_ms(3);
+}
+
+// Convert R,G,B to combined 32-bit color
+uint32_t LPD8806::Color(uint8_t r, uint8_t g, uint8_t b) {
+    // Take the lowest 7 bits of each value and append them end to end
+    // We have the top bit set high (its a 'parity-like' bit in the protocol
+    // and must be set!)
+    return 0x808080 | ((uint32_t)g << 16) | ((uint32_t)r << 8) | (uint32_t)b;
+}
+
+// store the rgb component in our array
+void LPD8806::setPixelColor(uint16_t n, uint8_t r, uint8_t g, uint8_t b) {
+    if (n >= numLEDs) return; // '>=' because arrays are 0-indexed
+
+    pixels[n*3  ] = g | 0x80;
+    pixels[n*3+1] = r | 0x80;
+    pixels[n*3+2] = b | 0x80;
+}
+
+void LPD8806::setPixelColor(uint16_t n, uint32_t c) {
+    if (n >= numLEDs) return; // '>=' because arrays are 0-indexed
+
+    pixels[n*3  ] = (c >> 16) | 0x80;
+    pixels[n*3+1] = (c >>  8) | 0x80;
+    pixels[n*3+2] =  c        | 0x80;
+}