SPI Communication Problem Between STM32F-Discovery and MAX31856 - stm32f4discovery

Question

I was trying to communicate my STM discovery board with MAX31856 using SPI communication. According to datasheet, I should send address byte first, then data bytes following. I am currently able to write to registers but when i try to read the data i wrote to registers, I couldn't read data unless I only send read command.
For example:
http://puu.sh/E2gJD.png
With this code, I am able to read default register values.
http://puu.sh/E2gLC.png
With this code, I am able to write new values to CR0 and CR1 registers. The first 0x80 value is register CR0's address byte. The next values are new register values 0x80 and 0x37.
http://puu.sh/E2gNK.png
I stopped the previous program and changed my code to this one. Then I started debugging. As you can see from this picture, the CR0 and CR1 register values are changed to what we wrote before.
Finally;
http://puu.sh/E2gRw.png
When I try to combine these two operations, writing and reading, I wasn't able to read what I wrote to registers. Need some help about solving this problem.
uint8_t spiTXData[17],spiRXData[17],spiTXDataR[17], spiRXDataR[17];
/* USER CODE END 0 */
HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_DAC_Init();
MX_SPI1_Init();
/* USER CODE BEGIN 2 */
// HAL_Delay ( 1 ) ;
//
// HAL_GPIO_WritePin(GPIOE, GPIO_PIN_3, GPIO_PIN_RESET);
// spiTXDataR[0] = 0x00;
// HAL_SPI_TransmitReceive(&hspi1, spiTXDataR, spiRXDataR, 3, 50);
// HAL_GPIO_WritePin(GPIOE, GPIO_PIN_3, GPIO_PIN_SET);
// HAL_Delay ( 1 ) ;
spiTXData[0] = 0x80;
spiTXData[1] = 0x80;
spiTXData[2] = 0x37;
HAL_GPIO_WritePin(GPIOE, GPIO_PIN_3, GPIO_PIN_RESET);
HAL_SPI_TransmitReceive(&hspi1, spiTXData, spiRXData, 3, 50);
HAL_GPIO_WritePin(GPIOE, GPIO_PIN_3, GPIO_PIN_SET);
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
spiTXDataR[0] = 0x00;
HAL_GPIO_WritePin(GPIOE, GPIO_PIN_3, GPIO_PIN_RESET);
HAL_SPI_TransmitReceive(&hspi1, spiTXDataR, spiRXDataR, 17, 50);
HAL_GPIO_WritePin(GPIOE, GPIO_PIN_3, GPIO_PIN_SET);
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
}
I need to be able to read the commands I write to CR0 and CR1 registers later. How can I do that? I hope you understand my problem and able to help me.
Thanks.

Answer 1

As far as I know there is no CR0 and CR1 but I assume what you are locking for is CR1 and CR2. You can read these values by either setting a pointer to the address of the register and reding the dereferenced pointer value like so:
uint32_t *ptr = REGISTER_ADDRESS;
variable = *ptr;
now variable should contain the registers value assuming that the regsiter you are looking for is a 32 bit register.
Another way is to use the premade "defines" true studio provides to read those values for example:
SPI1->CR1
In my case it is SPI1 but it depends on the how many SPIs your mcu has and which one you are using.
Usualy the Reference Manual and/or the Data Sheet that are provided by ST on their Website (specific one for each MCU or at least MCU family) are a pretty got help in figuring out the names of the registers and/or their addresses.