HOW to send 16bit over SPI

[ManishNair]

Hi,

I want to send five,16 bit data over SPI. WHile executing the code i cant see any transmission. What i wanted is

1. SS = 0 -> 16 bit data1 -> SS=1, SS = 0 -> 16 bit data2 -> SS=1,

or

2, SS=0 , word0, word1, word2,word3, word4 ss=1

i tried both methods but no action..

How to configure FifoThreshold and NSS. DDS_CS_Pin is CS and is connected to PD14

HAL_GPIO_WritePin(GPIOD,DDS_CS_Pin,0);

 HAL_Delay(1);

 HAL_SPI_Transmit(&hspi6, (uint8_t*)&DDS_CR, 2, 10);

 HAL_SPI_Transmit(&hspi6, (uint8_t*)&DDS_FL, 2, 10);

 HAL_SPI_Transmit(&hspi6, (uint8_t*)&DDS_FH, 2, 10);

 HAL_SPI_Transmit(&hspi6, (uint8_t*)&DDS_PR, 2, 10);

 HAL_SPI_Transmit(&hspi6, (uint8_t*)&DDS_RST,2, 10);

 HAL_Delay(1);

 HAL_GPIO_WritePin(GPIOD,DDS_CS_Pin,1);

static void MX_SPI6_Init(void)

{

 hspi6.Instance = SPI6;

 hspi6.Init.Mode = SPI_MODE_MASTER;

 hspi6.Init.Direction = SPI_DIRECTION_2LINES_TXONLY;

 hspi6.Init.DataSize = SPI_DATASIZE_16BIT;

 hspi6.Init.CLKPolarity = SPI_POLARITY_HIGH;

 hspi6.Init.CLKPhase = SPI_PHASE_1EDGE;

 hspi6.Init.NSS = SPI_NSS_SOFT;

 hspi6.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_64;

 hspi6.Init.FirstBit = SPI_FIRSTBIT_MSB;

 hspi6.Init.TIMode = SPI_TIMODE_DISABLE;

 hspi6.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;

 hspi6.Init.CRCPolynomial = 7;

 hspi6.Init.NSSPMode = SPI_NSS_SOFT;

 hspi6.Init.NSSPolarity = SPI_NSS_POLARITY_LOW;

 hspi6.Init.FifoThreshold = SPI_FIFO_THRESHOLD_01DATA;

 hspi6.Init.TxCRCInitializationPattern = SPI_CRC_INITIALIZATION_ALL_ZERO_PATTERN;

 hspi6.Init.RxCRCInitializationPattern = SPI_CRC_INITIALIZATION_ALL_ZERO_PATTERN;

 hspi6.Init.MasterSSIdleness = SPI_MASTER_SS_IDLENESS_00CYCLE;

 hspi6.Init.MasterInterDataIdleness = SPI_MASTER_INTERDATA_IDLENESS_00CYCLE;

 hspi6.Init.MasterReceiverAutoSusp = SPI_MASTER_RX_AUTOSUSP_DISABLE;

 hspi6.Init.MasterKeepIOState = SPI_MASTER_KEEP_IO_STATE_DISABLE;

 hspi6.Init.IOSwap = SPI_IO_SWAP_DISABLE;

 if (HAL_SPI_Init(&hspi6) != HAL_OK)

 {

  Error_Handler();

 }

}

its SPI is waiting for FIFO threshold and what is the threshold for follwoing ?

 hspi6.Init.FifoThreshold = SPI_FIFO_THRESHOLD_01DATA;

[Tesla DeLorean · Accepted solution]

>>HAL_SPI_Transmit(&hspi6, (uint8_t*)&DDS_CR, 2, 10);

Will observed that the count here is units of DataSize

[S.Ma · Accepted solution]

With the FIFO, you can actually stay in 8 bit SPI mode and write a 16 bit value in the DR.

they will be sliced in 2x8 by HW. only thing to take care is MSB/LSB ordering.

[ManishNair]

Thank you...

I tried both 8 and 16 bit, TI and Motorola, But No use.. Then i Put the transmission in an 0.5sec loop and observed transaction... but My DDS does not updated... used NSS and without NSS... Then i wrote the following program, it worked. AD9837 updated the regs and produced sine wave... So i think the SPI is waiting for some BUffer Fill up or threshold... and can't find any such thing other than FIFO threshold(which i tried)...

Any Information?

Next i want to interface 24bit 6 channel Sigma delta adc for which this 'trick' may not work...

I want to read all regs and set regs init almost 3 SPS...

I have a mind block to use DMA ,due to lack of knowledge and tickets raised here related to DMA issues...

How it is safe to use DMA ?

HAL_GPIO_WritePin(GPIOA,sck_Pin,1);

HAL_GPIO_WritePin(GPIOD,cs_Pin,0);

 ShifT(0);

 ShifT(0);

 ShifT(1);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(1);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 //FL = 0x50c7;

 ShifT(0);

 ShifT(1);

 ShifT(0);

 ShifT(0);

 ShifT(1);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 //FH = 0x400f;

 ShifT(0);

 ShifT(1);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(1);

 ShifT(0);

 ShifT(0);

 ShifT(1);

 ShifT(1);

 ShifT(1);

 ShifT(1);

 //PR = 0xc000;

 ShifT(1);

 ShifT(1);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 //RST =0x2000;

 ShifT(0);

 ShifT(0);

 ShifT(1);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 ShifT(0);

 HAL_GPIO_WritePin(GPIOA,sck_Pin,1);

 HAL_Delay(1);

 HAL_GPIO_WritePin(GPIOD,cs_Pin,1);

 HAL_GPIO_WritePin(GPIOA,mosi_Pin,1);

***************

void ShifT(int n)

{

if (n==0)

{

  HAL_GPIO_WritePin(GPIOA,mosi_Pin,0); // 0

}

else

{

  HAL_GPIO_WritePin(GPIOA,mosi_Pin,1); // 0

}

 DWT_Delay(10);

 HAL_GPIO_WritePin(GPIOA,sck_Pin,0);

 DWT_Delay(10);

 HAL_GPIO_WritePin(GPIOA,sck_Pin,1);

 DWT_Delay(10);

}

[Joerg Wagner]

I would recommend to use SPIS1, SPIS2 or SPIS3 because they have a 16 Bit FIFO.

SPI4..6 just have 8 Bit only.

Please read the documentation on page 2133 and 2134 in the Reference Manual RM0433 concerning half-duplex communication.