WS2812b/2811/6812灯珠 -- STM32F103 DMA-SPI方式驱动

最近在做一个STM32项目，需要驱动24位WS2812b RGB灯环。曾写下一篇博文《WS2812b/2811/6812灯珠 – STM32F103 CPU-SPI方式驱动》。原理是：用SPI来模拟WS2812b的驱动信号时序。虽然这个程序能够正常工作，但也有一些缺点，其中一个最明显的缺点是——发送数据要占用大量CPU时间。那么有没有一种更好的办法呢？
　　这个方法就是用DMA-SPI发送。CPU只需要把要发送的数据计算好，然后直接丢给DMA总线即可。

/* Define to prevent recursive inclusion -------------------------------------*/
#ifndef __WS2812B_H
#define __WS2812B_H

/* Includes ------------------------------------------------------------------*/
#include "main.h"

/* Exported types ------------------------------------------------------------*/
typedef struct
{
  u8 R;
  u8 G;
  u8 B;
}RGBColor_TypeDef;

/* Exported constants --------------------------------------------------------*/
#define Pixel_S1_NUM    24	//灯环-1 RGB数量

#define CODE0 0x80      //0xC0不适用
#define CODE1 0xF8      //0xFC不适用

/* Exported macro ------------------------------------------------------------*/
/* Exported variables --------------------------------------------------------*/
/* Exported functions ------------------------------------------------------- */
void WS2812b_Configuration(void);

/* Basic Color Effects -------------------------------------------------------*/
void RGB_RED(u16 Pixel_LEN);
void RGB_GREEN(u16 Pixel_LEN);
void RGB_BLUE(u16 Pixel_LEN);
void RGB_YELLOW(u16 Pixel_LEN);
void RGB_MAGENTA(u16 Pixel_LEN);
void RGB_BLACK(u16 Pixel_LEN);
void RGB_WHITE(u16 Pixel_LEN);

/* Complicated Color Effects -------------------------------------------------*/
void rainbowCycle(u8 Pixel_LEN);

#endif /* __WS2812B_H */

本程序中MCU的系统时钟为72MHz。应用RGB灯效的思路依然是先设定每个灯的颜色，然后用DMA一并发送出去。在打开两个高等级的平级中断的情况下，灯环上24位RGB的颜色正常。经过实际测试，110 pixels的灯带也能完美驱动！

/* Includes ------------------------------------------------------------------*/
#include "WS2812b.h"
/* Private typedef -----------------------------------------------------------*/
/* Some Static Colors --------------------------------------------------------*/
const RGBColor_TypeDef RED      = {255,0,0};
const RGBColor_TypeDef GREEN    = {0,255,0};
const RGBColor_TypeDef BLUE     = {0,0,255};
const RGBColor_TypeDef SKY      = {0,255,255};
const RGBColor_TypeDef MAGENTA  = {255,0,220};
const RGBColor_TypeDef YELLOW   = {127,216,0};
const RGBColor_TypeDef ORANGE   = {127,106,0};
const RGBColor_TypeDef BLACK    = {0,0,0};
const RGBColor_TypeDef WHITE    = {255,255,255};
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
u8 pixelBuffer[ Pixel_S1_NUM][24];

/* Private functions ---------------------------------------------------------*/
/**
  * @brief    WS2812B SPI总线初始化
  * @param    
  */
void WS2812b_Configuration(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;
  SPI_InitTypeDef  SPI_InitStructure;
  DMA_InitTypeDef DMA_InitStructure;
  
  /* PCLK2 = HCLK/2 */
  RCC_PCLK2Config(RCC_HCLK_Div2);
  /* Enable peripheral clocks ------------------------------------------------*/
  /* GPIOA,SPI1 and DMA1 clock enable */
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_SPI1, ENABLE);
  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);
  
  /* Configure SPI1 pin: MOSI ------------------------------------------------*/
  /* Confugure MOSI pin as Alternate Function Push Pull */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7 ;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
  
  /* SPI1 configuration ------------------------------------------------------*/
  SPI_InitStructure.SPI_Direction = SPI_Direction_1Line_Tx;     //SPI1-Tx_Only_Master
  SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
  SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;
  SPI_InitStructure.SPI_CPOL = SPI_CPOL_High;
  SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;
  SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
  SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_8;  //SPI1CLK=9MHz
  SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
  SPI_InitStructure.SPI_CRCPolynomial = 7;
  SPI_Init(SPI1, &SPI_InitStructure);
  
  /* Enable SPI1 */
  SPI_Cmd(SPI1, ENABLE);
  
  /* Enable SPI1 CRC calculation */
  SPI_CalculateCRC(SPI1, DISABLE);
  
  SPI_I2S_DMACmd(SPI1, SPI_I2S_DMAReq_Tx, ENABLE);
  
  DMA_DeInit(DMA1_Channel3);
  DMA_InitStructure.DMA_PeripheralBaseAddr      = (u32) &(SPI1 -> DR);
  DMA_InitStructure.DMA_MemoryBaseAddr          = (u32) &(*pixelBuffer);
  DMA_InitStructure.DMA_DIR                     = DMA_DIR_PeripheralDST;        //PeripheralBaseAddr为目标地址,即从pixelBuffer到SPI1 -> DR
  DMA_InitStructure.DMA_BufferSize              = ( Pixel_S1_NUM)*24;
  DMA_InitStructure.DMA_PeripheralInc           = DMA_PeripheralInc_Disable;
  DMA_InitStructure.DMA_MemoryInc               = DMA_MemoryInc_Enable;
  DMA_InitStructure.DMA_PeripheralDataSize      = DMA_PeripheralDataSize_Byte;
  DMA_InitStructure.DMA_MemoryDataSize          = DMA_MemoryDataSize_Byte;
  DMA_InitStructure.DMA_Mode                    = DMA_Mode_Normal;
  DMA_InitStructure.DMA_Priority                = DMA_Priority_High;
  DMA_InitStructure.DMA_M2M                     = DMA_M2M_Disable;
  DMA_Init(DMA1_Channel3, &DMA_InitStructure);
  
  /* RGB RESET ---------------------------------------------------------------*/
  Delay_1ms(1);
  RGB_BLACK(Pixel_S1_NUM  );
  Delay_1ms(1);
}

//设定某个RGB LED的颜色
void rgb_SetColor(unsigned char LedId, RGBColor_TypeDef Color)  
{
 	u8 i;
  if( LedId > ( Pixel_S1_NUM ) ) return; //to avoid overflow
  
  for(i=0;i<=7;i++)    pixelBuffer[LedId][i]= ( (Color.G & (1 << (7 -i)) )? (CODE1):CODE0 );
  for(i=8;i<=15;i++)   pixelBuffer[LedId][i]= ( (Color.R & (1 << (15-i)) )? (CODE1):CODE0 );
  for(i=16;i<=23;i++)  pixelBuffer[LedId][i]= ( (Color.B & (1 << (23-i)) )? (CODE1):CODE0 );

}

/**
  * @brief  Configure colors to RGB pixel series.群发
  * @param  RGBColor_TypeDef: pointer to a RGBColor_TypeDef structure that
  *         contains the color configuration information for the RGB pixel.
  * @retval None
  */
void rgb_SendArray(void)
{
  DMA_Cmd(DMA1_Channel3, DISABLE );
  DMA_ClearFlag(DMA1_FLAG_TC3);
  DMA_SetCurrDataCounter(DMA1_Channel3,( Pixel_S1_NUM ) * 24 );
  DMA_Cmd(DMA1_Channel3, ENABLE);
}

/* Basic Color Effects -------------------------------------------------------*/
/**
  * @brief  Configure the whole serial RGB pixels to red.
  * @param  Pixel_LEN: the account of RGB pixels in serial
  * @retval None
  */
void RGB_RED(u16 Pixel_LEN)
{
  u8 i;
  for(i=0;i