STM32F1-workarea : how to drive a WS2812 RGB LED using PWM and DMA

how to drive a WS2812 RGB LED using PWM and DMA

#include <stm32f10x.h>

void Delay(__IO uint32_t nCount)
{ 
  while(nCount--)
  { 
  }
}

#define TIM3_CCR1_Address 0x40000434  // physical memory address of Timer 3 CCR1 register

#define d2r (3.14159265/180)

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
DMA_InitTypeDef DMA_InitStructure;

/* Buffer that holds one complete DMA transmission
 * Ensure that this buffer is big enough to hold
 * all data bytes that need to be sent
 * 
 * The buffer size can be calculated as follows: number of LEDs * 24 bytes + 42 bytes
 * 
 * This leaves us with a maximum string length of (2^16 bytes per DMA stream - 42 bytes) / 24 bytes per LED = 2728 LEDs
 */
uint16_t LED_BYTE_Buffer[ 100 ];

/* this array holds the RGB values to represent a color wheel using 256 steps on each emitter 256^3 = 16777216 colors
 */
uint8_t eightbit[ 766 ][ 3 ] =
{
{ 255, 0, 0 },
{ 254, 1, 0 },
{ 253, 2, 0 },
{ 252, 3, 0 },
{ 251, 4, 0 },
{ 250, 5, 0 },
{ 249, 6, 0 },
{ 248, 7, 0 },
{ 247, 8, 0 },
{ 246, 9, 0 },
{ 245, 10, 0 },
{ 244, 11, 0 },
{ 243, 12, 0 },
{ 242, 13, 0 },
{ 241, 14, 0 },
{ 240, 15, 0 },
{ 239, 16, 0 },
{ 238, 17, 0 },
{ 237, 18, 0 },
{ 236, 19, 0 },
{ 235, 20, 0 },
{ 234, 21, 0 },
{ 233, 22, 0 },
{ 232, 23, 0 },
{ 231, 24, 0 },
{ 230, 25, 0 },
{ 229, 26, 0 },
{ 228, 27, 0 },
{ 227, 28, 0 },
{ 226, 29, 0 },
{ 225, 30, 0 },
{ 224, 31, 0 },
{ 223, 32, 0 },
{ 222, 33, 0 },
{ 221, 34, 0 },
{ 220, 35, 0 },
{ 219, 36, 0 },
{ 218, 37, 0 },
{ 217, 38, 0 },
{ 216, 39, 0 },
{ 215, 40, 0 },
{ 214, 41, 0 },
{ 213, 42, 0 },
{ 212, 43, 0 },
{ 211, 44, 0 },
{ 210, 45, 0 },
{ 209, 46, 0 },
{ 208, 47, 0 },
{ 207, 48, 0 },
{ 206, 49, 0 },
{ 205, 50, 0 },
{ 204, 51, 0 },
{ 203, 52, 0 },
{ 202, 53, 0 },
{ 201, 54, 0 },
{ 200, 55, 0 },
{ 199, 56, 0 },
{ 198, 57, 0 },
{ 197, 58, 0 },
{ 196, 59, 0 },
{ 195, 60, 0 },
{ 194, 61, 0 },
{ 193, 62, 0 },
{ 192, 63, 0 },
{ 191, 64, 0 },
{ 190, 65, 0 },
{ 189, 66, 0 },
{ 188, 67, 0 },
{ 187, 68, 0 },
{ 186, 69, 0 },
{ 185, 70, 0 },
{ 184, 71, 0 },
{ 183, 72, 0 },
{ 182, 73, 0 },
{ 181, 74, 0 },
{ 180, 75, 0 },
{ 179, 76, 0 },
{ 178, 77, 0 },
{ 177, 78, 0 },
{ 176, 79, 0 },
{ 175, 80, 0 },
{ 174, 81, 0 },
{ 173, 82, 0 },
{ 172, 83, 0 },
{ 171, 84, 0 },
{ 170, 85, 0 },
{ 169, 86, 0 },
{ 168, 87, 0 },
{ 167, 88, 0 },
{ 166, 89, 0 },
{ 165, 90, 0 },
{ 164, 91, 0 },
{ 163, 92, 0 },
{ 162, 93, 0 },
{ 161, 94, 0 },
{ 160, 95, 0 },
{ 159, 96, 0 },
{ 158, 97, 0 },
{ 157, 98, 0 },
{ 156, 99, 0 },
{ 155, 100, 0 },
{ 154, 101, 0 },
{ 153, 102, 0 },
{ 152, 103, 0 },
{ 151, 104, 0 },
{ 150, 105, 0 },
{ 149, 106, 0 },
{ 148, 107, 0 },
{ 147, 108, 0 },
{ 146, 109, 0 },
{ 145, 110, 0 },
{ 144, 111, 0 },
{ 143, 112, 0 },
{ 142, 113, 0 },
{ 141, 114, 0 },
{ 140, 115, 0 },
{ 139, 116, 0 },
{ 138, 117, 0 },
{ 137, 118, 0 },
{ 136, 119, 0 },
{ 135, 120, 0 },
{ 134, 121, 0 },
{ 133, 122, 0 },
{ 132, 123, 0 },
{ 131, 124, 0 },
{ 130, 125, 0 },
{ 129, 126, 0 },
{ 128, 127, 0 },
{ 127, 128, 0 },
{ 126, 129, 0 },
{ 125, 130, 0 },
{ 124, 131, 0 },
{ 123, 132, 0 },
{ 122, 133, 0 },
{ 121, 134, 0 },
{ 120, 135, 0 },
{ 119, 136, 0 },
{ 118, 137, 0 },
{ 117, 138, 0 },
{ 116, 139, 0 },
{ 115, 140, 0 },
{ 114, 141, 0 },
{ 113, 142, 0 },
{ 112, 143, 0 },
{ 111, 144, 0 },
{ 110, 145, 0 },
{ 109, 146, 0 },
{ 108, 147, 0 },
{ 107, 148, 0 },
{ 106, 149, 0 },
{ 105, 150, 0 },
{ 104, 151, 0 },
{ 103, 152, 0 },
{ 102, 153, 0 },
{ 101, 154, 0 },
{ 100, 155, 0 },
{ 99, 156, 0 },
{ 98, 157, 0 },
{ 97, 158, 0 },
{ 96, 159, 0 },
{ 95, 160, 0 },
{ 94, 161, 0 },
{ 93, 162, 0 },
{ 92, 163, 0 },
{ 91, 164, 0 },
{ 90, 165, 0 },
{ 89, 166, 0 },
{ 88, 167, 0 },
{ 87, 168, 0 },
{ 86, 169, 0 },
{ 85, 170, 0 },
{ 84, 171, 0 },
{ 83, 172, 0 },
{ 82, 173, 0 },
{ 81, 174, 0 },
{ 80, 175, 0 },
{ 79, 176, 0 },
{ 78, 177, 0 },
{ 77, 178, 0 },
{ 76, 179, 0 },
{ 75, 180, 0 },
{ 74, 181, 0 },
{ 73, 182, 0 },
{ 72, 183, 0 },
{ 71, 184, 0 },
{ 70, 185, 0 },
{ 69, 186, 0 },
{ 68, 187, 0 },
{ 67, 188, 0 },
{ 66, 189, 0 },
{ 65, 190, 0 },
{ 64, 191, 0 },
{ 63, 192, 0 },
{ 62, 193, 0 },
{ 61, 194, 0 },
{ 60, 195, 0 },
{ 59, 196, 0 },
{ 58, 197, 0 },
{ 57, 198, 0 },
{ 56, 199, 0 },
{ 55, 200, 0 },
{ 54, 201, 0 },
{ 53, 202, 0 },
{ 52, 203, 0 },
{ 51, 204, 0 },
{ 50, 205, 0 },
{ 49, 206, 0 },
{ 48, 207, 0 },
{ 47, 208, 0 },
{ 46, 209, 0 },
{ 45, 210, 0 },
{ 44, 211, 0 },
{ 43, 212, 0 },
{ 42, 213, 0 },
{ 41, 214, 0 },
{ 40, 215, 0 },
{ 39, 216, 0 },
{ 38, 217, 0 },
{ 37, 218, 0 },
{ 36, 219, 0 },
{ 35, 220, 0 },
{ 34, 221, 0 },
{ 33, 222, 0 },
{ 32, 223, 0 },
{ 31, 224, 0 },
{ 30, 225, 0 },
{ 29, 226, 0 },
{ 28, 227, 0 },
{ 27, 228, 0 },
{ 26, 229, 0 },
{ 25, 230, 0 },
{ 24, 231, 0 },
{ 23, 232, 0 },
{ 22, 233, 0 },
{ 21, 234, 0 },
{ 20, 235, 0 },
{ 19, 236, 0 },
{ 18, 237, 0 },
{ 17, 238, 0 },
{ 16, 239, 0 },
{ 15, 240, 0 },
{ 14, 241, 0 },
{ 13, 242, 0 },
{ 12, 243, 0 },
{ 11, 244, 0 },
{ 10, 245, 0 },
{ 9, 246, 0 },
{ 8, 247, 0 },
{ 7, 248, 0 },
{ 6, 249, 0 },
{ 5, 250, 0 },
{ 4, 251, 0 },
{ 3, 252, 0 },
{ 2, 253, 0 },
{ 1, 254, 0 },
{ 0, 255, 0 },
{ 0, 254, 1 },
{ 0, 253, 2 },
{ 0, 252, 3 },
{ 0, 251, 4 },
{ 0, 250, 5 },
{ 0, 249, 6 },
{ 0, 248, 7 },
{ 0, 247, 8 },
{ 0, 246, 9 },
{ 0, 245, 10 },
{ 0, 244, 11 },
{ 0, 243, 12 },
{ 0, 242, 13 },
{ 0, 241, 14 },
{ 0, 240, 15 },
{ 0, 239, 16 },
{ 0, 238, 17 },
{ 0, 237, 18 },
{ 0, 236, 19 },
{ 0, 235, 20 },
{ 0, 234, 21 },
{ 0, 233, 22 },
{ 0, 232, 23 },
{ 0, 231, 24 },
{ 0, 230, 25 },
{ 0, 229, 26 },
{ 0, 228, 27 },
{ 0, 227, 28 },
{ 0, 226, 29 },
{ 0, 225, 30 },
{ 0, 224, 31 },
{ 0, 223, 32 },
{ 0, 222, 33 },
{ 0, 221, 34 },
{ 0, 220, 35 },
{ 0, 219, 36 },
{ 0, 218, 37 },
{ 0, 217, 38 },
{ 0, 216, 39 },
{ 0, 215, 40 },
{ 0, 214, 41 },
{ 0, 213, 42 },
{ 0, 212, 43 },
{ 0, 211, 44 },
{ 0, 210, 45 },
{ 0, 209, 46 },
{ 0, 208, 47 },
{ 0, 207, 48 },
{ 0, 206, 49 },
{ 0, 205, 50 },
{ 0, 204, 51 },
{ 0, 203, 52 },
{ 0, 202, 53 },
{ 0, 201, 54 },
{ 0, 200, 55 },
{ 0, 199, 56 },
{ 0, 198, 57 },
{ 0, 197, 58 },
{ 0, 196, 59 },
{ 0, 195, 60 },
{ 0, 194, 61 },
{ 0, 193, 62 },
{ 0, 192, 63 },
{ 0, 191, 64 },
{ 0, 190, 65 },
{ 0, 189, 66 },
{ 0, 188, 67 },
{ 0, 187, 68 },
{ 0, 186, 69 },
{ 0, 185, 70 },
{ 0, 184, 71 },
{ 0, 183, 72 },
{ 0, 182, 73 },
{ 0, 181, 74 },
{ 0, 180, 75 },
{ 0, 179, 76 },
{ 0, 178, 77 },
{ 0, 177, 78 },
{ 0, 176, 79 },
{ 0, 175, 80 },
{ 0, 174, 81 },
{ 0, 173, 82 },
{ 0, 172, 83 },
{ 0, 171, 84 },
{ 0, 170, 85 },
{ 0, 169, 86 },
{ 0, 168, 87 },
{ 0, 167, 88 },
{ 0, 166, 89 },
{ 0, 165, 90 },
{ 0, 164, 91 },
{ 0, 163, 92 },
{ 0, 162, 93 },
{ 0, 161, 94 },
{ 0, 160, 95 },
{ 0, 159, 96 },
{ 0, 158, 97 },
{ 0, 157, 98 },
{ 0, 156, 99 },
{ 0, 155, 100 },
{ 0, 154, 101 },
{ 0, 153, 102 },
{ 0, 152, 103 },
{ 0, 151, 104 },
{ 0, 150, 105 },
{ 0, 149, 106 },
{ 0, 148, 107 },
{ 0, 147, 108 },
{ 0, 146, 109 },
{ 0, 145, 110 },
{ 0, 144, 111 },
{ 0, 143, 112 },
{ 0, 142, 113 },
{ 0, 141, 114 },
{ 0, 140, 115 },
{ 0, 139, 116 },
{ 0, 138, 117 },
{ 0, 137, 118 },
{ 0, 136, 119 },
{ 0, 135, 120 },
{ 0, 134, 121 },
{ 0, 133, 122 },
{ 0, 132, 123 },
{ 0, 131, 124 },
{ 0, 130, 125 },
{ 0, 129, 126 },
{ 0, 128, 127 },
{ 0, 127, 128 },
{ 0, 126, 129 },
{ 0, 125, 130 },
{ 0, 124, 131 },
{ 0, 123, 132 },
{ 0, 122, 133 },
{ 0, 121, 134 },
{ 0, 120, 135 },
{ 0, 119, 136 },
{ 0, 118, 137 },
{ 0, 117, 138 },
{ 0, 116, 139 },
{ 0, 115, 140 },
{ 0, 114, 141 },
{ 0, 113, 142 },
{ 0, 112, 143 },
{ 0, 111, 144 },
{ 0, 110, 145 },
{ 0, 109, 146 },
{ 0, 108, 147 },
{ 0, 107, 148 },
{ 0, 106, 149 },
{ 0, 105, 150 },
{ 0, 104, 151 },
{ 0, 103, 152 },
{ 0, 102, 153 },
{ 0, 101, 154 },
{ 0, 100, 155 },
{ 0, 99, 156 },
{ 0, 98, 157 },
{ 0, 97, 158 },
{ 0, 96, 159 },
{ 0, 95, 160 },
{ 0, 94, 161 },
{ 0, 93, 162 },
{ 0, 92, 163 },
{ 0, 91, 164 },
{ 0, 90, 165 },
{ 0, 89, 166 },
{ 0, 88, 167 },
{ 0, 87, 168 },
{ 0, 86, 169 },
{ 0, 85, 170 },
{ 0, 84, 171 },
{ 0, 83, 172 },
{ 0, 82, 173 },
{ 0, 81, 174 },
{ 0, 80, 175 },
{ 0, 79, 176 },
{ 0, 78, 177 },
{ 0, 77, 178 },
{ 0, 76, 179 },
{ 0, 75, 180 },
{ 0, 74, 181 },
{ 0, 73, 182 },
{ 0, 72, 183 },
{ 0, 71, 184 },
{ 0, 70, 185 },
{ 0, 69, 186 },
{ 0, 68, 187 },
{ 0, 67, 188 },
{ 0, 66, 189 },
{ 0, 65, 190 },
{ 0, 64, 191 },
{ 0, 63, 192 },
{ 0, 62, 193 },
{ 0, 61, 194 },
{ 0, 60, 195 },
{ 0, 59, 196 },
{ 0, 58, 197 },
{ 0, 57, 198 },
{ 0, 56, 199 },
{ 0, 55, 200 },
{ 0, 54, 201 },
{ 0, 53, 202 },
{ 0, 52, 203 },
{ 0, 51, 204 },
{ 0, 50, 205 },
{ 0, 49, 206 },
{ 0, 48, 207 },
{ 0, 47, 208 },
{ 0, 46, 209 },
{ 0, 45, 210 },
{ 0, 44, 211 },
{ 0, 43, 212 },
{ 0, 42, 213 },
{ 0, 41, 214 },
{ 0, 40, 215 },
{ 0, 39, 216 },
{ 0, 38, 217 },
{ 0, 37, 218 },
{ 0, 36, 219 },
{ 0, 35, 220 },
{ 0, 34, 221 },
{ 0, 33, 222 },
{ 0, 32, 223 },
{ 0, 31, 224 },
{ 0, 30, 225 },
{ 0, 29, 226 },
{ 0, 28, 227 },
{ 0, 27, 228 },
{ 0, 26, 229 },
{ 0, 25, 230 },
{ 0, 24, 231 },
{ 0, 23, 232 },
{ 0, 22, 233 },
{ 0, 21, 234 },
{ 0, 20, 235 },
{ 0, 19, 236 },
{ 0, 18, 237 },
{ 0, 17, 238 },
{ 0, 16, 239 },
{ 0, 15, 240 },
{ 0, 14, 241 },
{ 0, 13, 242 },
{ 0, 12, 243 },
{ 0, 11, 244 },
{ 0, 10, 245 },
{ 0, 9, 246 },
{ 0, 8, 247 },
{ 0, 7, 248 },
{ 0, 6, 249 },
{ 0, 5, 250 },
{ 0, 4, 251 },
{ 0, 3, 252 },
{ 0, 2, 253 },
{ 0, 1, 254 },
{ 0, 0, 255 },
{ 1, 0, 254 },
{ 2, 0, 253 },
{ 3, 0, 252 },
{ 4, 0, 251 },
{ 5, 0, 250 },
{ 6, 0, 249 },
{ 7, 0, 248 },
{ 8, 0, 247 },
{ 9, 0, 246 },
{ 10, 0, 245 },
{ 11, 0, 244 },
{ 12, 0, 243 },
{ 13, 0, 242 },
{ 14, 0, 241 },
{ 15, 0, 240 },
{ 16, 0, 239 },
{ 17, 0, 238 },
{ 18, 0, 237 },
{ 19, 0, 236 },
{ 20, 0, 235 },
{ 21, 0, 234 },
{ 22, 0, 233 },
{ 23, 0, 232 },
{ 24, 0, 231 },
{ 25, 0, 230 },
{ 26, 0, 229 },
{ 27, 0, 228 },
{ 28, 0, 227 },
{ 29, 0, 226 },
{ 30, 0, 225 },
{ 31, 0, 224 },
{ 32, 0, 223 },
{ 33, 0, 222 },
{ 34, 0, 221 },
{ 35, 0, 220 },
{ 36, 0, 219 },
{ 37, 0, 218 },
{ 38, 0, 217 },
{ 39, 0, 216 },
{ 40, 0, 215 },
{ 41, 0, 214 },
{ 42, 0, 213 },
{ 43, 0, 212 },
{ 44, 0, 211 },
{ 45, 0, 210 },
{ 46, 0, 209 },
{ 47, 0, 208 },
{ 48, 0, 207 },
{ 49, 0, 206 },
{ 50, 0, 205 },
{ 51, 0, 204 },
{ 52, 0, 203 },
{ 53, 0, 202 },
{ 54, 0, 201 },
{ 55, 0, 200 },
{ 56, 0, 199 },
{ 57, 0, 198 },
{ 58, 0, 197 },
{ 59, 0, 196 },
{ 60, 0, 195 },
{ 61, 0, 194 },
{ 62, 0, 193 },
{ 63, 0, 192 },
{ 64, 0, 191 },
{ 65, 0, 190 },
{ 66, 0, 189 },
{ 67, 0, 188 },
{ 68, 0, 187 },
{ 69, 0, 186 },
{ 70, 0, 185 },
{ 71, 0, 184 },
{ 72, 0, 183 },
{ 73, 0, 182 },
{ 74, 0, 181 },
{ 75, 0, 180 },
{ 76, 0, 179 },
{ 77, 0, 178 },
{ 78, 0, 177 },
{ 79, 0, 176 },
{ 80, 0, 175 },
{ 81, 0, 174 },
{ 82, 0, 173 },
{ 83, 0, 172 },
{ 84, 0, 171 },
{ 85, 0, 170 },
{ 86, 0, 169 },
{ 87, 0, 168 },
{ 88, 0, 167 },
{ 89, 0, 166 },
{ 90, 0, 165 },
{ 91, 0, 164 },
{ 92, 0, 163 },
{ 93, 0, 162 },
{ 94, 0, 161 },
{ 95, 0, 160 },
{ 96, 0, 159 },
{ 97, 0, 158 },
{ 98, 0, 157 },
{ 99, 0, 156 },
{ 100, 0, 155 },
{ 101, 0, 154 },
{ 102, 0, 153 },
{ 103, 0, 152 },
{ 104, 0, 151 },
{ 105, 0, 150 },
{ 106, 0, 149 },
{ 107, 0, 148 },
{ 108, 0, 147 },
{ 109, 0, 146 },
{ 110, 0, 145 },
{ 111, 0, 144 },
{ 112, 0, 143 },
{ 113, 0, 142 },
{ 114, 0, 141 },
{ 115, 0, 140 },
{ 116, 0, 139 },
{ 117, 0, 138 },
{ 118, 0, 137 },
{ 119, 0, 136 },
{ 120, 0, 135 },
{ 121, 0, 134 },
{ 122, 0, 133 },
{ 123, 0, 132 },
{ 124, 0, 131 },
{ 125, 0, 130 },
{ 126, 0, 129 },
{ 127, 0, 128 },
{ 128, 0, 127 },
{ 129, 0, 126 },
{ 130, 0, 125 },
{ 131, 0, 124 },
{ 132, 0, 123 },
{ 133, 0, 122 },
{ 134, 0, 121 },
{ 135, 0, 120 },
{ 136, 0, 119 },
{ 137, 0, 118 },
{ 138, 0, 117 },
{ 139, 0, 116 },
{ 140, 0, 115 },
{ 141, 0, 114 },
{ 142, 0, 113 },
{ 143, 0, 112 },
{ 144, 0, 111 },
{ 145, 0, 110 },
{ 146, 0, 109 },
{ 147, 0, 108 },
{ 148, 0, 107 },
{ 149, 0, 106 },
{ 150, 0, 105 },
{ 151, 0, 104 },
{ 152, 0, 103 },
{ 153, 0, 102 },
{ 154, 0, 101 },
{ 155, 0, 100 },
{ 156, 0, 99 },
{ 157, 0, 98 },
{ 158, 0, 97 },
{ 159, 0, 96 },
{ 160, 0, 95 },
{ 161, 0, 94 },
{ 162, 0, 93 },
{ 163, 0, 92 },
{ 164, 0, 91 },
{ 165, 0, 90 },
{ 166, 0, 89 },
{ 167, 0, 88 },
{ 168, 0, 87 },
{ 169, 0, 86 },
{ 170, 0, 85 },
{ 171, 0, 84 },
{ 172, 0, 83 },
{ 173, 0, 82 },
{ 174, 0, 81 },
{ 175, 0, 80 },
{ 176, 0, 79 },
{ 177, 0, 78 },
{ 178, 0, 77 },
{ 179, 0, 76 },
{ 180, 0, 75 },
{ 181, 0, 74 },
{ 182, 0, 73 },
{ 183, 0, 72 },
{ 184, 0, 71 },
{ 185, 0, 70 },
{ 186, 0, 69 },
{ 187, 0, 68 },
{ 188, 0, 67 },
{ 189, 0, 66 },
{ 190, 0, 65 },
{ 191, 0, 64 },
{ 192, 0, 63 },
{ 193, 0, 62 },
{ 194, 0, 61 },
{ 195, 0, 60 },
{ 196, 0, 59 },
{ 197, 0, 58 },
{ 198, 0, 57 },
{ 199, 0, 56 },
{ 200, 0, 55 },
{ 201, 0, 54 },
{ 202, 0, 53 },
{ 203, 0, 52 },
{ 204, 0, 51 },
{ 205, 0, 50 },
{ 206, 0, 49 },
{ 207, 0, 48 },
{ 208, 0, 47 },
{ 209, 0, 46 },
{ 210, 0, 45 },
{ 211, 0, 44 },
{ 212, 0, 43 },
{ 213, 0, 42 },
{ 214, 0, 41 },
{ 215, 0, 40 },
{ 216, 0, 39 },
{ 217, 0, 38 },
{ 218, 0, 37 },
{ 219, 0, 36 },
{ 220, 0, 35 },
{ 221, 0, 34 },
{ 222, 0, 33 },
{ 223, 0, 32 },
{ 224, 0, 31 },
{ 225, 0, 30 },
{ 226, 0, 29 },
{ 227, 0, 28 },
{ 228, 0, 27 },
{ 229, 0, 26 },
{ 230, 0, 25 },
{ 231, 0, 24 },
{ 232, 0, 23 },
{ 233, 0, 22 },
{ 234, 0, 21 },
{ 235, 0, 20 },
{ 236, 0, 19 },
{ 237, 0, 18 },
{ 238, 0, 17 },
{ 239, 0, 16 },
{ 240, 0, 15 },
{ 241, 0, 14 },
{ 242, 0, 13 },
{ 243, 0, 12 },
{ 244, 0, 11 },
{ 245, 0, 10 },
{ 246, 0, 9 },
{ 247, 0, 8 },
{ 248, 0, 7 },
{ 249, 0, 6 },
{ 250, 0, 5 },
{ 251, 0, 4 },
{ 252, 0, 3 },
{ 253, 0, 2 },
{ 254, 0, 1 },
{ 255, 0, 0 }, };

void Timer3_init( void )
{
  uint16_t PrescalerValue;
  
  RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOA, ENABLE );

  /* GPIOA Configuration: TIM3 Channel 1 as alternate function push-pull */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init( GPIOA, &GPIO_InitStructure );
  
  RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM3, ENABLE );

  /* Compute the prescaler value */
  PrescalerValue = (uint16_t) ( SystemCoreClock / 24000000 ) - 1;
  /* Time base configuration */
  TIM_TimeBaseStructure.TIM_Period = 29; // 800kHz 
  TIM_TimeBaseStructure.TIM_Prescaler = PrescalerValue;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseInit( TIM3, &TIM_TimeBaseStructure );
  
  /* PWM1 Mode configuration: Channel1 */
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 0;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
  TIM_OC1Init( TIM3, &TIM_OCInitStructure );
  
  /* configure DMA */
  /* DMA clock enable */
  RCC_AHBPeriphClockCmd( RCC_AHBPeriph_DMA1, ENABLE );
  
  /* DMA1 Channel6 Config */
  DMA_DeInit( DMA1_Channel6 );
  
  DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t) TIM3_CCR1_Address; // physical address of Timer 3 CCR1
  DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t) LED_BYTE_Buffer; // this is the buffer memory 
  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST; // data shifted from memory to peripheral
  DMA_InitStructure.DMA_BufferSize = 42;
  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; // automatically increase buffer index
  DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
  DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
  DMA_InitStructure.DMA_Mode = DMA_Mode_Normal; // stop DMA feed after buffer size is reached
  DMA_InitStructure.DMA_Priority = DMA_Priority_High;
  DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
  
  DMA_Init( DMA1_Channel6, &DMA_InitStructure );
  
  /* TIM3 CC1 DMA Request enable */
  TIM_DMACmd( TIM3, TIM_DMA_CC1, ENABLE );
}

/* This function sends data bytes out to a string of WS2812s
 * The first argument is a pointer to the first RGB triplet to be sent -- color
 * The seconds argument is the number of LEDs in the chain -- len
 * 
 * This will result in the RGB triplet passed by argument 1 being sent to 
 * the LED that is the furthest away from the controller (the point where
 * data is injected into the chain)
 */
void WS2812_send( uint8_t (*color)[ 3 ], uint16_t len )
{
  uint8_t i, j;
  uint8_t led;
  uint16_t memaddr;
  uint16_t buffersize;
  
  buffersize = ( len * 24 ) + 42; // number of bytes needed is #LEDs * 24 bytes + 42 trailing bytes

  memaddr = 0;        // reset buffer memory index
  led = 0;          // reset led index
    
  // fill transmit buffer with correct compare values to achieve
  // correct pulse widths according to color values
  while ( len )
  {
    for ( j = 0; j < 8; j++ )         // GREEN data
    {
      if ( ( color[ led ][ 1 ] << j ) & 0x80 ) // data sent MSB first, j = 0 is MSB j = 7 is LSB
      {
        LED_BYTE_Buffer[ memaddr ] = 17;  // compare value for logical 1
      }
      else
      {
        LED_BYTE_Buffer[ memaddr ] = 9; // compare value for logical 0
      }
      memaddr++;
    }
    
    for ( j = 0; j < 8; j++ )         // RED data
    {
      if ( ( color[ led ][ 0 ] << j ) & 0x80 ) // data sent MSB first, j = 0 is MSB j = 7 is LSB
      {
        LED_BYTE_Buffer[ memaddr ] = 17;  // compare value for logical 1
      }
      else
      {
        LED_BYTE_Buffer[ memaddr ] = 9; // compare value for logical 0
      }
      memaddr++;
    }
    
    for ( j = 0; j < 8; j++ )         // BLUE data
    {
      if ( ( color[ led ][ 2 ] << j ) & 0x80 ) // data sent MSB first, j = 0 is MSB j = 7 is LSB
      {
        LED_BYTE_Buffer[ memaddr ] = 17;  // compare value for logical 1
      }
      else
      {
        LED_BYTE_Buffer[ memaddr ] = 9; // compare value for logical 0
      }
      memaddr++;
    }
    
    led++;
    len--;
  }
  
  // add needed delay at end of byte cycle, pulsewidth = 0
  while ( memaddr < buffersize )
  {
    LED_BYTE_Buffer[ memaddr ] = 0;
    memaddr++;
  }
  
  DMA_SetCurrDataCounter( DMA1_Channel6, buffersize ); // load number of bytes to be transferred
  DMA_Cmd( DMA1_Channel6, ENABLE );       // enable DMA channel 6
  TIM_Cmd( TIM3, ENABLE );            // enable Timer 3
  while ( !DMA_GetFlagStatus( DMA1_FLAG_TC6 ) )
    ;   // wait until transfer complete

  TIM_Cmd( TIM3, DISABLE );           // disable Timer 3
  DMA_Cmd( DMA1_Channel6, DISABLE );      // disable DMA channel 6
  DMA_ClearFlag( DMA1_FLAG_TC6 ); // clear DMA1 Channel 6 transfer complete flag
}

int main( void )
{
  Timer3_init( );
  
  int16_t i;
  
  while ( 1 )
  {
    /* first cycle through the colors on 2 LEDs chained together
     * last LED in the chain will receive first sent triplet
     * --> last LED in the chain will 'lead' 
     */
    for ( i = 0; i < 766; i += 2 )
    {
      WS2812_send( &eightbit[ i ], 2 );
      Delay( 50000L );
    }
    
    /* cycle through the colors on only one LED
     * this time only the first LED that data is 
     * fed into will update
     */
    for ( i = 0; i < 766; i += 1 )
    {
      WS2812_send( &eightbit[ i ], 1 );
      Delay( 50000L );
    }
  }
}