2018年12月28日 | STM32用PWM +DMA驱动 WS2812

参考的代码：

------------------------------------WS2812B.c------------------------------------

#include "WS2812B.h"

/* 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

 */

#define TIM3_CCR3_Address 0x4000043c // physical memory address of Timer 3 CCR1 register

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

//#define TIM2_CCR4_Address 0x40000040

#define TIMING_ONE  61

#define TIMING_ZERO 29

 uint16_t LED_BYTE_Buffer[300];

 uint16_t testcount = 0;

  uint16_t testcount1 = 0;

//---------------------------------------------------------------//

void Timer2_init(void)

{

TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;

  TIM_OCInitTypeDef  TIM_OCInitStructure;

  GPIO_InitTypeDef GPIO_InitStructure;

  DMA_InitTypeDef DMA_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);

/* GPIOA Configuration: TIM2 Channel 1 as alternate function push-pull */

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_Init(GPIOA, &GPIO_InitStructure);

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

/* Compute the prescaler value */

//PrescalerValue = (uint16_t) (SystemCoreClock / 24000000) - 1;

/* Time base configuration */

TIM_TimeBaseStructure.TIM_Period = 90-1; // 800kHz 

TIM_TimeBaseStructure.TIM_Prescaler = 0;

TIM_TimeBaseStructure.TIM_ClockDivision = 0;

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

/* PWM1 Mode configuration: Channel1 */

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;

TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

TIM_OCInitStructure.TIM_Pulse = 0;

TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

TIM_OC1Init(TIM2, &TIM_OCInitStructure);

  TIM_OC1PreloadConfig(TIM2, TIM_OCPreload_Enable);

//  TIM_ARRPreloadConfig(TIM3, ENABLE);

//GPIO_PinRemapConfig(GPIO_PartialRemap_TIM3,ENABLE);

/* configure DMA */

/* DMA clock enable */

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);

/* DMA1 Channel6 Config */

DMA_DeInit(DMA1_Channel2);

DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)(&TIM2->CCR1);// 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_Channel2, &DMA_InitStructure);

/* TIM3 CC1 DMA Request enable */

TIM_DMACmd(TIM2, TIM_DMA_Update, 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

 * The seconds argument is the number of LEDs in the chain

 * 

 * 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;

uint16_t memaddr;

uint16_t buffersize;

buffersize = (len*24)+10;// number of bytes needed is #LEDs * 24 bytes + 42 trailing bytes

memaddr = 0;// reset buffer memory index

while (len)

{

for(i=0; i<8; i++) // GREEN data

{

LED_BYTE_Buffer[memaddr] = ((color[0][1]<

memaddr++;

}

for(i=0; i<8; i++) // RED

{

LED_BYTE_Buffer[memaddr] = ((color[0][0]<

memaddr++;

}

for(i=0; i<8; i++) // BLUE

{

LED_BYTE_Buffer[memaddr] = ((color[0][2]<

memaddr++;

}

  len--;

}

//===================================================================//

//bug：最后一个周期波形不知道为什么全是高电平，故增加一个波形

  //LED_BYTE_Buffer[memaddr] = ((color[0][2]<<8) & 0x0080) ? TIMING_ONE:TIMING_ZERO;

//===================================================================//

  memaddr++;

while(memaddr < buffersize)

{

LED_BYTE_Buffer[memaddr] = 0;

memaddr++;

}

DMA_SetCurrDataCounter(DMA1_Channel2, memaddr); // load number of bytes to be transferred

    DMA_Cmd(DMA1_Channel2, ENABLE); // enable DMA channel 6

TIM_Cmd(TIM2, ENABLE); // enable Timer 3

while(!DMA_GetFlagStatus(DMA1_FLAG_TC2)) 

    {

//      testcount1 = DMA_GetCurrDataCounter(DMA1_Channel2);

//      if(DMA_GetFlagStatus(DMA1_FLAG_TE2))

//      {

//        testcount++;

//      }

    }; // wait until transfer complete

//  testcount++;

    TIM_Cmd(TIM2, DISABLE); // disable Timer 3

DMA_Cmd(DMA1_Channel2, DISABLE); // disable DMA channel 6

DMA_ClearFlag(DMA1_FLAG_TC2); // clear DMA1 Channel 6 transfer complete flag

}

----------------------------------------Main.c---------------------------------------------

uint8_t r[][3] = {255,0,0};

uint8_t g[][3] = {0,255,0};

uint8_t b[][3] = {0,0,255};

uint8_t cheng[][3] = {255,128,0};

uint8_t huang[][3] = {255,255,0};

uint8_t qing[][3] = {0,255,255};

uint8_t zi[][3] = {128,0,255};

uint32_t testt = (uint32_t)(&TIM3->CCR3);

 int main(void)

 {

    //RCC_Configuration();

    delay_init();    //延时函数初始化  

    //LED_Init();  //初始化与LED连接的硬件接口

    Timer2_init();

while(1)

{

WS2812_send(r,8);

delay_ms(1000);

WS2812_send(g,8);

delay_ms(1000);

WS2812_send(b,8);

delay_ms(1000);

    WS2812_send(cheng,8);

delay_ms(1000);

WS2812_send(huang,8);

delay_ms(1000);

WS2812_send(qing,8);

delay_ms(1000);

    WS2812_send(zi,8);

delay_ms(1000);

}

 }

需要注意以下几点：

1）采用的是TIM2->CH1,用的是TIM_DMA_Update触发，如果改用其他的通道需要更改触发方式

2）代码中---bug：最后一个周期波形不知道为什么全是高电平，故增加一个波形

可以注销此句代码，主要是  buffersize = (len*24)+10;不知道为什么需要加上10，加上1就不行，不知道什么原因，那位知道可以探讨下。