在开发STM32F031芯片的项目时同时用到了串口DMA发送和SPI的DMA,因为两个功能我独立开发,开发完成之后准备移植到一起,结果代码运行出问题,检查后发现是串口发送DMA和SPI的接收DMA共用了DMA1_Channel2,于是马上翻看手册,嘿,还真看到了好消息。在STM32F1 系列与 STM32F0 系列移植手册的表9.STM32F1 系列与 STM32F0 系列之间的 DMA 请求区别 中发现了这个大宝贝:
USART1除了使用通道2和3还可以使用通道4和5。
于是马上修改代码,编译后再调试。。。。。。。。。。不行啊!!!!!
检查配置,没错啊,不过是换通道而已,那到底怎么回事,总不能手册从写错了吧,于是开始搜索之路,就在地铁上突然看到有人遇到同样的问题,最后说的是需要重映像,于是就去找库函数,别说,还真有。
void SYSCFG_DMAChannelRemapConfig(uint32_t SYSCFG_DMARemap, FunctionalState NewState)函数。函数原型如下:
/**
* [url=home.php?mod=space&uid=247401]@brief[/url] Configure the DMA channels remapping.
* @param SYSCFG_DMARemap: selects the DMA channels remap.
* This parameter can be one of the following values:
* [url=home.php?mod=space&uid=2817080]@ARG[/url] SYSCFG_DMARemap_TIM17: Remap TIM17 DMA requests from channel1 to channel2
* @arg SYSCFG_DMARemap_TIM16: Remap TIM16 DMA requests from channel3 to channel4
* @arg SYSCFG_DMARemap_USART1Rx: Remap USART1 Rx DMA requests from channel3 to channel5
* @arg SYSCFG_DMARemap_USART1Tx: Remap USART1 Tx DMA requests from channel2 to channel4
* @arg SYSCFG_DMARemap_ADC1: Remap ADC1 DMA requests from channel1 to channel2
* @param NewState: new state of the DMA channel remapping.
* This parameter can be: ENABLE or DISABLE.
* [url=home.php?mod=space&uid=536309]@NOTE[/url] When enabled, DMA channel of the selected peripheral is remapped
* @note When disabled, Default DMA channel is mapped to the selected peripheral
* @note By default TIM17 DMA requests is mapped to channel 1,
* use SYSCFG_DMAChannelRemapConfig(SYSCFG_DMARemap_TIM17, Enable) to remap
* TIM17 DMA requests to channel 2 and use
* SYSCFG_DMAChannelRemapConfig(SYSCFG_DMARemap_TIM17, Disable) to map
* TIM17 DMA requests to channel 1 (default mapping)
* @note This function is only used for STM32F030, STM32F031, STM32F042, STM32F072 and STM32F051 devices.
* @retval None
*/
void SYSCFG_DMAChannelRemapConfig(uint32_t SYSCFG_DMARemap, FunctionalState NewState)
{
/* Check the parameters */
assert_param(IS_SYSCFG_DMA_REMAP(SYSCFG_DMARemap));
assert_param(IS_FUNCTIONAL_STATE(NewState));
if (NewState != DISABLE)
{
/* Remap the DMA channel */
SYSCFG->CFGR1 |= (uint32_t)SYSCFG_DMARemap;
}
else
{
/* use the default DMA channel mapping */
SYSCFG->CFGR1 &= (uint32_t)(~SYSCFG_DMARemap);
}
}
@arg SYSCFG_DMARemap_USART1Tx: Remap USART1 Tx DMA requests from channel2 to channel4
将串口1的DMA发送从通道2重映射到通道4。雾操,我这英语4级没过的都看懂了,简直欣喜若狂,感觉用起来。
已经水了这么多了,结贴吧,结果确实没问题,不过还要打开SYSCFG的时钟,这是重点。不然又是一个坑。下面把我的贴出来:
//DMA的通道二被SPI占用,此处使用SYSCFG_DMAChannelRemapConfig将DMA通道重定向
void MYDMA_485_Config(void)
{
DMA_InitTypeDef DMA_InitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE); //使能SYSCFG时钟,必须的
SYSCFG_DMAChannelRemapConfig(SYSCFG_DMARemap_USART1Tx, ENABLE);//将DMA串口发送从通道2重映射到通道4
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE); //使能DMA传输
SPI_DMA1_MEM_LEN = 11;
DMA_InitStructure.DMA_PeripheralBaseAddr = USART1_BASE+0x28; //DMA外设基地址
DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)RS485_TX_BUF; //DMA内存基地址
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST; //数据传输方向,从内存读取发送到外设
DMA_InitStructure.DMA_BufferSize = SPI_DMA1_MEM_LEN; //DMA通道的DMA缓存的大小
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable; //外设地址寄存器不变
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; //内存地址寄存器递增
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte; //数据宽度为8位
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte; //数据宽度为8位
DMA_InitStructure.DMA_Mode = DMA_Mode_Normal; //工作在正常缓存模式
DMA_InitStructure.DMA_Priority = DMA_Priority_Medium; //DMA通道 x拥有中优先级
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable; //DMA通道x没有设置为内存到内存传输
DMA_Init(DMA1_Channel4, &DMA_InitStructure); //根据DMA_InitStruct中指定的参数初始化DMA的通道USART1_Tx_DMA_Channel所标识的寄存器
DMA_Cmd(DMA1_Channel4, ENABLE); //使能USART1 TX DMA1 所指示的通道
}
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