Posted on November 26, 2014 at 11:17Hi everybody,
As suggested by Jan, I divide the problem in three part: first, learn to set up the timer, then leran to set up SPI with ''manual'' ''filling'' of data register, and then learn to set up the DMA.'' The first part is completed as I am able to set two Timer in PWM mode. (See attachment). Now configuring the SPI I have many questions:
1- Should I define the NSS, SCK,MISO, MOSI pins as follow:
/* GPIOA, GPIOB & GPIOC Clocks enable */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA | RCC_AHBPeriph_GPIOB |RCC_AHBPeriph_GPIOC, ENABLE);
/********************************************SPI Configuration*************************************/
/*Configuration pins used by SP2:
* SPI2_NSS = PB12
* SPI2_SCK = PB13
* SPI2_MISO = PB14 //for FULL DUPLEX; Will not be used in our case?
* SPI2_MOSI = PB15 */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12 | GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
GPIO_PinAFConfig(GPIOB, GPIO_PinSource12, GPIO_AF_5); //NSS PB12 AF5
GPIO_PinAFConfig(GPIOB, GPIO_PinSource13, GPIO_AF_5); //SCK PB13 AF5
GPIO_PinAFConfig(GPIOB, GPIO_PinSource14, GPIO_AF_5); //MISO PB14 AF5
GPIO_PinAFConfig(GPIOB, GPIO_PinSource15, GPIO_AF_5); //MOSI PB15 AF5
2- Knowing that I'll be in simplex mode ( The SPI will only transmit data => RXONLY=0 of SPI2_CR2 register), and that I want a DMA TIM triggered on SPI, should I used the DMA Tx?
I'm getting confused on that point.
The rerence Manual says on that point:
''When starting communication using DMA...these steps must be followed in order:
* Enable DMA Rx buffer....not my case as DMA_Rx is unused in my case
*Enable DMA streams for Tx and Rx in DMA registers, if the streams are used (Yes)
*Enable DMA Tx buffer in the TXDMAEN bit in the SPI_CR2 register, if DMA_Tx is used
*Enable the SPI by setting the SPE bit.
3- So, as in my case it is the DMA which is triggered by a timer and send datas taken in SRAM to SPI should i define the SPI as usual in a normal way enabeling the clock, the mode, data size, clock phase and polarity controls,data frame format......
Thanks for your feedback on that points.
Franck
