STM32G031 SPI read problems

[Barber.Mark]

i am using the STM32G031 and the SPI1 port. i have used the SPI port many times on various STM32F devices. I have found some of the STM32G devices have odd behavior. Today i have a strange problem i am running 16 bit SPI1 and when i observe the waveforms i am getting what i expect. However the return value is always 0. despite the waveform showing a value. Waveform attached, yellow CS light Blue clock purple MOSI dark blue MISO

this is my init code, i do not use HAL had too many problems in the past.

I suspect i have overlooked something, most likely obvious, but cannot find it.

void spi1_init(void)

{

// initilise SPI1 port

// PA1 - SCK

// PA2 - MOSI

// PA3 - MISO

// AF0

RCC->APBENR2|=RCC_APBENR2_SPI1EN;

// setup alternative registers

GPIOA->MODER&=~(GPIO_MODER_MODE1_0|GPIO_MODER_MODE2_0|GPIO_MODER_MODE3_0);

GPIOA->MODER|=(GPIO_MODER_MODE1_1|GPIO_MODER_MODE2_1|GPIO_MODER_MODE3_1);

// setup the AF number 0

GPIOA->AFR[0]&=~(GPIO_AFRL_AFSEL1_3|GPIO_AFRL_AFSEL1_2|GPIO_AFRL_AFSEL1_1|GPIO_AFRL_AFSEL1_0);

GPIOA->AFR[0]&=~(GPIO_AFRL_AFSEL2_3|GPIO_AFRL_AFSEL2_2|GPIO_AFRL_AFSEL2_1|GPIO_AFRL_AFSEL2_0);

GPIOA->AFR[0]&=~(GPIO_AFRL_AFSEL3_3|GPIO_AFRL_AFSEL3_2|GPIO_AFRL_AFSEL3_1|GPIO_AFRL_AFSEL3_0);

// set for very high speed

GPIOA->OSPEEDR|=GPIO_OSPEEDR_OSPEED1_0|GPIO_OSPEEDR_OSPEED1_1;

GPIOA->OSPEEDR|=GPIO_OSPEEDR_OSPEED2_0|GPIO_OSPEEDR_OSPEED2_1;

GPIOA->OSPEEDR|=GPIO_OSPEEDR_OSPEED3_0|GPIO_OSPEEDR_OSPEED3_1;

// now setup SPI1 registers

// setup clock rate to 40MHz

SPI1->CR1|=(SPI_CR1_BR);

// bidirectional mode

SPI1->CR1&=~SPI_CR1_BIDIMODE;

// we are the master

SPI1->CR1|=SPI_CR1_MSTR;

// CPOL clock idle low

SPI2->CR1&=~SPI_CR1_CPOL;

// CPHA clock transistion

SPI2->CR1&=~SPI_CR1_CPHA;

// set LSBFIRST low we send MSB first

SPI2->CR1&=~SPI_CR1_LSBFIRST;

// configure data size 16 bit

SPI1->CR2|=(SPI_CR2_DS_3|SPI_CR2_DS_2|SPI_CR2_DS_1|SPI_CR2_DS_0);

//SPI2->CR2&=~SPI_CR2_DS_3;

// configure RXNE threshold to 16 bit

SPI1->CR2&=~SPI_CR2_FRXTH;

// set up SSM pin

SPI1->CR1|=SPI_CR1_SSM;

// set up SSI pin

SPI1->CR1|=SPI_CR1_SSI;

// enable SPI port

SPI1->CR1|=SPI_CR1_SPE;

}

[waclawek.jan]

Code looks OK.

Read out and check/post content of SPI and relevant GPIO registers.

Check HW (think of bad solder joints and shorts). 

JW