Heroic Robotics / SD600A

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Fork of SD600A by Heroic Robotics

LPD8806.cpp@0:12e734116fea, 2011-12-16 (annotated)

Committer:
ehbmbed2
Date:
Fri Dec 16 03:16:50 2011 +0000
Revision:
0:12e734116fea
Child:
1:6ebd3ac910b6
first revision, works, needs to be tested on long strands

Who changed what in which revision?

UserRevisionLine numberNew contents of line
ehbmbed2 0:12e734116fea 1 // Mbed library to control LPD8806-based RGB LED Strips
ehbmbed2 0:12e734116fea 2 // (c) 2011 Jelmer Tiete
ehbmbed2 0:12e734116fea 3 // This library is ported from the Arduino implementation of Adafruit Industries
ehbmbed2 0:12e734116fea 4 // found at: http://github.com/adafruit/LPD8806
ehbmbed2 0:12e734116fea 5 // and their strips: http://www.adafruit.com/products/306
ehbmbed2 0:12e734116fea 6 // Released under the MIT License: http://mbed.org/license/mit
ehbmbed2 0:12e734116fea 7
ehbmbed2 0:12e734116fea 8 /*****************************************************************************/
ehbmbed2 0:12e734116fea 9
ehbmbed2 0:12e734116fea 10 #include "LPD8806.h"
ehbmbed2 0:12e734116fea 11
ehbmbed2 0:12e734116fea 12 //Define SPI pins
ehbmbed2 0:12e734116fea 13 SPI spi(p5, p6, p7); // mosi, miso, sclk
ehbmbed2 0:12e734116fea 14 //SPI spi(p11, p12, p13); // mosi, miso, sclk
ehbmbed2 0:12e734116fea 15
ehbmbed2 0:12e734116fea 16 LPD8806::LPD8806(uint16_t n) {
ehbmbed2 0:12e734116fea 17 // Allocate 3 bytes per pixel:
ehbmbed2 0:12e734116fea 18 if (NULL != (pixels = (uint8_t *)malloc(numLEDs * 3))) {
ehbmbed2 0:12e734116fea 19 memset(pixels, 0x80, numLEDs * 3); // Init to RGB 'off' state
ehbmbed2 0:12e734116fea 20 numLEDs = n;
ehbmbed2 0:12e734116fea 21 }
ehbmbed2 0:12e734116fea 22 }
ehbmbed2 0:12e734116fea 23
ehbmbed2 0:12e734116fea 24 void LPD8806::begin(void) {
ehbmbed2 0:12e734116fea 25
ehbmbed2 0:12e734116fea 26 // Setup the spi for 8 bit data, low steady state clock,
ehbmbed2 0:12e734116fea 27 // first edge capture, with a 2MHz clock rate
ehbmbed2 0:12e734116fea 28 spi.format(8,0);
ehbmbed2 0:12e734116fea 29 spi.frequency(2000000);
ehbmbed2 0:12e734116fea 30
ehbmbed2 0:12e734116fea 31 // Issue initial latch to 'wake up' strip (latch length varies w/numLEDs)
ehbmbed2 0:12e734116fea 32 writezeros(3 * ((numLEDs + 63) / 64));
ehbmbed2 0:12e734116fea 33 }
ehbmbed2 0:12e734116fea 34
ehbmbed2 0:12e734116fea 35 uint16_t LPD8806::numPixels(void) {
ehbmbed2 0:12e734116fea 36 return numLEDs;
ehbmbed2 0:12e734116fea 37 }
ehbmbed2 0:12e734116fea 38
ehbmbed2 0:12e734116fea 39 void LPD8806::writezeros(uint16_t n) {
ehbmbed2 0:12e734116fea 40 while (n--) spi.write(0x00);
ehbmbed2 0:12e734116fea 41 }
ehbmbed2 0:12e734116fea 42
ehbmbed2 0:12e734116fea 43 // This is how data is pushed to the strip. Unfortunately, the company
ehbmbed2 0:12e734116fea 44 // that makes the chip didnt release the protocol document or you need
ehbmbed2 0:12e734116fea 45 // to sign an NDA or something stupid like that, but we reverse engineered
ehbmbed2 0:12e734116fea 46 // this from a strip controller and it seems to work very nicely!
ehbmbed2 0:12e734116fea 47 void LPD8806::show(void) {
ehbmbed2 0:12e734116fea 48 uint16_t i, nl3 = numLEDs * 3; // 3 bytes per LED
ehbmbed2 0:12e734116fea 49
ehbmbed2 0:12e734116fea 50 for (i=0; i<nl3; i++ ) {
ehbmbed2 0:12e734116fea 51 spi.write(pixels[i]);
ehbmbed2 0:12e734116fea 52 }
ehbmbed2 0:12e734116fea 53
ehbmbed2 0:12e734116fea 54 // Write latch at end of data; latch length varies with number of LEDs
ehbmbed2 0:12e734116fea 55 writezeros(3 * ((numLEDs + 63) / 64));
ehbmbed2 0:12e734116fea 56
ehbmbed2 0:12e734116fea 57 // We need to have a delay here, a few ms seems to do the job
ehbmbed2 0:12e734116fea 58 // shorter may be OK as well - need to experiment :(
ehbmbed2 0:12e734116fea 59 // wait_ms(3);
ehbmbed2 0:12e734116fea 60 }
ehbmbed2 0:12e734116fea 61
ehbmbed2 0:12e734116fea 62 // Convert R,G,B to combined 32-bit color
ehbmbed2 0:12e734116fea 63 uint32_t LPD8806::Color(uint8_t r, uint8_t g, uint8_t b) {
ehbmbed2 0:12e734116fea 64 // Take the lowest 7 bits of each value and append them end to end
ehbmbed2 0:12e734116fea 65 // We have the top bit set high (its a 'parity-like' bit in the protocol
ehbmbed2 0:12e734116fea 66 // and must be set!)
ehbmbed2 0:12e734116fea 67 return 0x808080 | ((uint32_t)g << 16) | ((uint32_t)r << 8) | (uint32_t)b;
ehbmbed2 0:12e734116fea 68 }
ehbmbed2 0:12e734116fea 69
ehbmbed2 0:12e734116fea 70 // store the rgb component in our array
ehbmbed2 0:12e734116fea 71 void LPD8806::setPixelColor(uint16_t n, uint8_t r, uint8_t g, uint8_t b) {
ehbmbed2 0:12e734116fea 72 if (n >= numLEDs) return; // '>=' because arrays are 0-indexed
ehbmbed2 0:12e734116fea 73
ehbmbed2 0:12e734116fea 74 pixels[n*3 ] = g | 0x80;
ehbmbed2 0:12e734116fea 75 pixels[n*3+1] = r | 0x80;
ehbmbed2 0:12e734116fea 76 pixels[n*3+2] = b | 0x80;
ehbmbed2 0:12e734116fea 77 }
ehbmbed2 0:12e734116fea 78
ehbmbed2 0:12e734116fea 79 void LPD8806::setPixelColor(uint16_t n, uint32_t c) {
ehbmbed2 0:12e734116fea 80 if (n >= numLEDs) return; // '>=' because arrays are 0-indexed
ehbmbed2 0:12e734116fea 81
ehbmbed2 0:12e734116fea 82 pixels[n*3 ] = (c >> 16) | 0x80;
ehbmbed2 0:12e734116fea 83 pixels[n*3+1] = (c >> 8) | 0x80;
ehbmbed2 0:12e734116fea 84 pixels[n*3+2] = c | 0x80;
ehbmbed2 0:12e734116fea 85 }