DMA SPI need 2 read S2LP Module

[Quentin_27]

Hi everyone,
I'm currently working on project witch use SPi with DMA and S2LP Module

I have a function that initializes the DMA portion :

In my code I try to read information in DMA through the SpiritDeviceVersion and SpiritReadnbinfifo functions:

However, I get my data, but only when I call a DMA read 2 times :

nbOctetRecuB = the value I should read from nbOctetRecuA (0xC1)

nbOctetRecuB2 = the value I should read from nbOctetRecuB (0x0A, my FIFO element count)

nbOctetRecuC = the value I should read from nbOctetRecuB2 (0x0A, my FIFO element count) => whereas I expect 0xC1.

Below are one of those function:

I don't understand witch element is missing, why i need to perform another DMA operation to get my data ?

Just a heads-up, a double DMA operation is needed : so if I read S2LP register with DMA, and after Reread DMA without using SPI (ex no CS command) i get my data, this is what it tell me the problem isen't from the SPI ?

Is anyone get tis issue ?

Tanks for your time, Regards.

[mƎALLEm]

Hello @Quentin_27 ,

Please use </> button to share your code instead of pasting screenshots. Please read How to insert source code.

Thank you for your understanding.

[Andrew Neil]

Does it work OK without DMA ?

Have you used an oscilloscope or logic analyser to see what's actually happening on the SPI wires?

[Quentin_27]

Hi,

Yes it works without DMA,

All is correct on SPI Wires as you can see below  (Last ligne is CS#, Frequency 1MHz, and I have try 4MHz):

Tanks for your time, Regards.

[Andrew Neil]

Thanks for the LA screenshot.

Does it show the DMA or non-DMA case?

Do you see any differences?

[Quentin_27]

That's the problem, I havent any differences on SPI bus..
The Screenshot show the DMA-case , so when i'm using DMA actually, i need to do that to get my data and not the previous :

//-----------------------------------------------------------------------------
uint8_t SpiritDeviceVersion (void)
//-----------------------------------------------------------------------------
{
	volatile uint8_t	toto;

	g_SPI_DMA_TxBuffer[0] = (HEADER_READ | HEADER_ADDRESS);
	g_SPI_DMA_TxBuffer[1] = (S2LP_REG_DEVICE_INFO0); 		// 0xF1
	g_SPI_DMA_TxBuffer[2] = (0x00);


	S2LP_CS_DEBUT;
	DMA1_Channel2->CNDTR = 0x03;			//3 data
	DMA1_Channel1->CNDTR = 0x03;			//3 data


	//Activation des 2 canaux
	DMA1_Channel2->CCR |= DMA_CCR_EN;
	DMA1_Channel1->CCR |= DMA_CCR_EN;




	while(DMA1_Channel1->CNDTR != 0) asm("nop");
	while(DMA1_Channel2->CNDTR != 0) asm("nop");

	//	S2LP_SpiReadWrite (HEADER_READ | HEADER_ADDRESS);
	//	S2LP_SpiReadWrite (0xF1);
	//	toto=S2LP_SpiReadWrite (0x00);
	S2LP_CS_FIN;

	//Activation des 2 canaux
	DMA1_Channel1->CCR &= ~DMA_CCR_EN;
	DMA1_Channel2->CCR &= ~DMA_CCR_EN;




	//==========================2eme lecture==========================
	DMA1_Channel2->CNDTR = 0x03;			//3 data
	DMA1_Channel1->CNDTR = 0x03;			//3 data

	DMA1_Channel2->CCR |= DMA_CCR_EN;
	DMA1_Channel1->CCR |= DMA_CCR_EN;

//	while(DMA1_Channel1->CNDTR != 0) asm("nop");
//	while(DMA1_Channel2->CNDTR != 0) asm("nop");

	while (!(DMA1->ISR & DMA_ISR_TCIF2))
	{
	    // NOP ou rien
	    asm("nop");
	}
	DMA1->IFCR = DMA_IFCR_CTCIF2;          // clear flag

	DMA1_Channel1->CCR &= ~DMA_CCR_EN;
	DMA1_Channel2->CCR &= ~DMA_CCR_EN;

	//==========================Fin 2eme lecture=======================



	toto = g_SPI_DMA_RxBuffer[2];
	return toto;	//**** Spirit1 : 0x30 attendu *****
	//**** S2LP    : 0x91 attendu *****

}

I have try another flag to check DMA here but no difference.
Tanks for your time, Regards.