Posted on October 21, 2016 at 08:53Dear all,
I want to read MAX31855 by stm32F070xx in degree celsius.
Kindly take a look in this code, how can I implement it to 32f0xx?
#define SPI_PORT SPI2
#define SPI_SCK_PIN GPIO_Pin_13 // PB13
#define SPI_MISO_PIN GPIO_Pin_14 // PB14
#define SPI_CS_PIN GPIO_Pin_12 // PB12
#define SPI_GPIO_PORT GPIOB
void max31855_init() {
RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB,ENABLE);
GPIO_InitTypeDef PORT;
PORT.GPIO_Speed = GPIO_Speed_50MHz;
PORT.GPIO_Pin = SPI_MISO_PIN | SPI_SCK_PIN;
PORT.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOB,&PORT);
PORT.GPIO_Speed = GPIO_Speed_50MHz;
PORT.GPIO_Pin = SPI_CS_PIN;
PORT.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(GPIOB,&PORT);
SPI_InitTypeDef SPI;
SPI.SPI_Mode = SPI_Mode_Master;
SPI.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_256;
SPI.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
SPI.SPI_CPOL = SPI_CPOL_Low;
SPI.SPI_CPHA = SPI_CPHA_2Edge;
SPI.SPI_DataSize = SPI_DataSize_16b;
SPI.SPI_FirstBit = SPI_FirstBit_MSB;
SPI.SPI_NSS = SPI_NSS_Soft;
SPI_Init(SPI_PORT,&SPI);
SPI_NSSInternalSoftwareConfig(SPI_PORT,SPI_NSSInternalSoft_Set);
SPI_Cmd(SPI_PORT,ENABLE);
GPIO_SetBits(SPI_GPIO_PORT,SPI_CS_PIN);
}
uint16_t max31855_ReadData() {
while (SPI_I2S_GetFlagStatus(SPI_PORT,SPI_I2S_FLAG_TXE) == RESET); // Wait while DR register is not empty
SPI_I2S_SendData(SPI_PORT,0x0F); // Send byte to SPI
while (SPI_I2S_GetFlagStatus(SPI_PORT,SPI_I2S_FLAG_RXNE) == RESET); // Wait to receive byte
return SPI_I2S_ReceiveData(SPI_PORT); // Read byte from SPI bus
}
double max31855_readCelsius() {
uint32_t v = 0;
GPIO_ResetBits(SPI_GPIO_PORT,SPI_CS_PIN);
v = (uint32_t)max31855_ReadData() << 16 | max31855_ReadData(); // получаем две по�?ылки по 16 байт
GPIO_SetBits(SPI_GPIO_PORT,SPI_CS_PIN);
float internal = (v >> 4) & 0x7FF;
internal *= 0.0625;
if ((v >> 4) & 0x800)
internal *= -1;
if (v & 0x7) {
return -333; // чето не так
}
if (v & 0x80000000) {
v = 0xFFFFC000 | ((v >> 18) & 0x00003FFFF);
}
else {
v >>= 18;
}
double centigrade = v;
centigrade *= 0.25;
return centigrade;
People used in this way also,
void MAX31855_chipUnselect()
{
HAL_GPIO_WritePin(GPIOB, GPIO_TEMP_SO, GPIO_TEMP_/CS);
}
void MAX31855_chipSelect()
{
HAL_GPIO_WritePin(GPIOB,GPIO_TEMP_/CS, GPIO_PIN_RESET);
}
uint32_t MAX31855_readData()
{
uint8_t pDataRx[4] = { };
MAX31855_chipSelect();
HAL_SPI_Receive(&hspi1, (uint8_t*) pDataRx, 4, 1000);
MAX31855_chipUnselect();
return (pDataRx[i] << 24) | (pDataRx[i] << 16) | (pDataRx[i] << 8) | pDataRx[i];
}
1. How could I change first code to second format for celsius ?
2.MAX31855 is not bidirectional,can I follow this idea, http://www.ba0sh1.com/2014/05/31/howto-use-stm32-spi-half-duplex-mode/
Help me please.
Hasan
