STM32F767 and SPI communication without DMA

[Pilous Droip]

Posted on May 30, 2018 at 08:34

Hello friends,

I try SPI communication, and I have a problem. I only send data.... But how to receive it?

Connection is:

1. one master - one slave

2. Full duplex

Initialize:

LL_SPI_InitTypeDef SPI_InitStruct;

LL_GPIO_InitTypeDef GPIO_InitStruct;

LL_SPI_Disable(SPI1);

LL_AHB1_GRP1_EnableClockLL_AHB1_GRP1_PERIPH_GPIOA);

LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_SPI1);

/* SPI2 GPIO Configuration */

GPIO_InitStruct.Pin = LL_GPIO_PIN_5; GPIO_InitStruct.Mode = LL_GPIO_MODE_ALTERNATE; GPIO_InitStruct.Speed = LL_GPIO_SPEED_FREQ_VERY_HIGH; GPIO_InitStruct.OutputType = LL_GPIO_OUTPUT_PUSHPULL; GPIO_InitStruct.Pull = LL_GPIO_PULL_NO; GPIO_InitStruct.Alternate = LL_GPIO_AF_5; LL_GPIO_Init(GPIOA, &GPIO_InitStruct); GPIO_InitStruct.Pin = LL_GPIO_PIN_7; GPIO_InitStruct.Mode = LL_GPIO_MODE_ALTERNATE; GPIO_InitStruct.Speed = LL_GPIO_SPEED_FREQ_VERY_HIGH; GPIO_InitStruct.OutputType = LL_GPIO_OUTPUT_PUSHPULL; GPIO_InitStruct.Pull = LL_GPIO_PULL_NO; GPIO_InitStruct.Alternate = LL_GPIO_AF_5; LL_GPIO_Init(GPIOA, &GPIO_InitStruct); GPIO_InitStruct.Pin = LL_GPIO_PIN_6; GPIO_InitStruct.Mode = LL_GPIO_MODE_ALTERNATE; GPIO_InitStruct.Speed = LL_GPIO_SPEED_FREQ_VERY_HIGH; GPIO_InitStruct.OutputType = LL_GPIO_OUTPUT_PUSHPULL; GPIO_InitStruct.Pull = LL_GPIO_PULL_NO; GPIO_InitStruct.Alternate = LL_GPIO_AF_5; LL_GPIO_Init(GPIOA, &GPIO_InitStruct); GPIO_InitStruct.Pin = LL_GPIO_PIN_4; GPIO_InitStruct.Mode = LL_GPIO_MODE_ALTERNATE; GPIO_InitStruct.Speed = LL_GPIO_SPEED_FREQ_VERY_HIGH; GPIO_InitStruct.OutputType = LL_GPIO_OUTPUT_PUSHPULL; GPIO_InitStruct.Pull = LL_GPIO_PULL_NO; GPIO_InitStruct.Alternate = LL_GPIO_AF_5; LL_GPIO_Init(GPIOA, &GPIO_InitStruct);

/* SPI1 parameter configuration*/

SPI_InitStruct.TransferDirection = LL_SPI_FULL_DUPLEX; SPI_InitStruct.Mode = LL_SPI_MODE_MASTER; SPI_InitStruct.DataWidth = LL_SPI_DATAWIDTH_8BIT; SPI_InitStruct.ClockPolarity = LL_SPI_POLARITY_HIGH; SPI_InitStruct.ClockPhase = LL_SPI_PHASE_1EDGE; SPI_InitStruct.NSS = LL_SPI_NSS_HARD_OUTPUT; SPI_InitStruct.BaudRate = LL_SPI_BAUDRATEPRESCALER_DIV64; SPI_InitStruct.BitOrder = LL_SPI_MSB_FIRST; SPI_InitStruct.CRCCalculation = LL_SPI_CRCCALCULATION_DISABLE; SPI_InitStruct.CRCPoly = 7; LL_SPI_Init(SPI1, &SPI_InitStruct);

LL_SPI_SetStandard(SPI1, LL_SPI_PROTOCOL_MOTOROLA);

LL_SPI_EnableNSSPulseMgt(SPI1);

LL_SPI_SetRxFIFOThreshold(SPI1, LL_SPI_RX_FIFO_TH_QUARTER);

/* Configure SPI1 transfer interrupts */

/* Enable RXNE Interrupt */ LL_SPI_EnableIT_RXNE(SPI1);

LL_SPI_Enable(SPI1);

And function to write/read....

int32_t read_from_reg(SPI_TypeDef *SPI, uint8_t data, uint8_t *SPI_Data_receive)

{ LL_SPI_TransmitData8(SPI, data); while (!LL_SPI_IsActiveFlag_TXE(SPI)); while (!LL_SPI_IsActiveFlag_RXNE(SPI)); while (LL_SPI_IsActiveFlag_BSY(SPI)); *SPI_Data_receive = LL_SPI_ReceiveData8(SPI);

return 0;

}

And I sent one byte and I don't receive anything. Any idea, how to receive some data from register?

#nucleo-f767zi #stm32f7-spi Note: this post was migrated and contained many threaded conversations, some content may be missing.

[stm322399]

Posted on May 30, 2018 at 13:14

Strange that the code shows initialisation with HARD_OUTPUT (the code must enable SSOE) and registers tell that SSI+SSM are one whereas they should be zero. Are you sure to run the right code ?

[Pilous Droip]

Posted on May 30, 2018 at 13:17

I modification my code to control NSS pin by software:

GPIO_InitStruct.Pin = LL_GPIO_PIN_4;

GPIO_InitStruct.Mode = LL_GPIO_MODE_OUTPUT; GPIO_InitStruct.Speed = LL_GPIO_SPEED_FREQ_VERY_HIGH; GPIO_InitStruct.OutputType = LL_GPIO_OUTPUT_PUSHPULL; GPIO_InitStruct.Pull = LL_GPIO_PULL_NO; LL_GPIO_Init(GPIOA, &GPIO_InitStruct);

and here is my log scope, where I send 3 dummy and read 3 bytes.... 

🙂

 Now, it is work, but ......

[Pilous Droip]

Posted on May 30, 2018 at 13:25

A modif the function to use : LL_SPI_NSS_HARD_OUTPUT

And now egister is set:

SSOE = 0x01

SSI = 0x01

SSM = 0x00

[T J]

Posted on May 30, 2018 at 13:37

SR

• RXNE = 0x01   /* here I see a problem ....*/

every 8 clock cycles the Rx register will have the value of the MISO pins.

and RXNE is set.

[stm322399]

Posted on May 30, 2018 at 13:41

Well, the SPI has 4 words FIFO, so that you can write 4 times to DR in a row and the SPI shall generate the correct waveform with CE down for the duration of 4 time 8-bit characters. Can you observe that ? Then manage your reception.

[T J]

Posted on May 30, 2018 at 13:50

Some peripherals like the nSS to be active between bytes,

But others like it to run over the whole command.

where is the nSS line trace ?

[Pilous Droip]

Posted on May 30, 2018 at 14:04

🙂

 NSS = CE on my picture. 

[T J]

Posted on May 30, 2018 at 17:41

Can you see that nSS is not high then going low to start the command.

you need nSS to be high on startup.

[waclawek.jan]

Posted on May 31, 2018 at 13:00

If the same simple program works when PA15 is used as NSS, but not if PA4 is used as NSS, then it's time to talk to ST's support...

JW

[Pilous Droip]

Posted on May 31, 2018 at 15:16

I reconnected it back to PA4 and it's working.

Because my first test function was without LL_SPI_Enable/LL_SPI_Disable.