Dear ST Community Members,
I tried to understand...page 25 ST LISDE12.pdf
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Data are transmitted in byte format (DATA). Each data transfer contains 8 bits. The number
of bytes transferred per transfer is unlimited. Data is transferred with the Most Significant bit
(MSb) first. If a receiver can’t receive another complete byte of data until it has performed
some other function, it can hold the clock line, SCL low to force the transmitter into a wait
state. Data transfer only continues when the receiver is ready for another byte and releases
the data line. If a slave receiver doesn’t acknowledge the slave address (i.e. it is not able to
receive because it is performing some real-time function) the data line must be left HIGH by
the slave. The master can then abort the transfer. A low-to-high transition on the SDA line
while the SCL line is HIGH is defined as a STOP condition. Each data transfer must be
terminated by the generation of a STOP (SP) condition.
In order to read multiple bytes, it is necessary to assert the most significant bit of the subaddress
field. In other words, SUB(7) must be equal to 1 while SUB(6-0) represents the
address of the first register to be read.
In the presented communication format MAK is Master acknowledge and NMAK is No
Master Acknowledge.
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Table 16 to Table 19....
How can I generate SAK and SUB ?
Here's the code I have made :
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_4, GPIO_PIN_SET); //ACC_CS =1 I2C MODE
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_5, GPIO_PIN_RESET); //ACC_A0 =0 SA0=0
HAL_Delay(100);
//WHO_AM_I, read ,register address 0F 000 1111, 00110011 = 33h page 30 ST LIS2DE12
buffer[0] = 0x0F;
HAL_I2C_Master_Transmit(&hi2c1, 0x31>>1 ,buffer ,1, 100); //transmit one byte to ST LIS2DE12
//HAL_StatusTypeDef HAL_I2C_Master_Transmit(I2C_HandleTypeDef *hi2c, uint16_t DevAddress, uint8_t *pData, uint16_t Size, uint32_t Timeout)
// put HAL_I2C_Receive after this give a delay 10ms, how many bytes do I want to read from the register.
HAL_Delay(10);
HAL_I2C_Master_Receive(&hi2c1, 0x31>>1 ,buffer ,2, 100); //receive one byte to ST LIS2DE12
//HAL_StatusTypeDef HAL_I2C_Master_Receive(I2C_HandleTypeDef *hi2c, uint16_t DevAddress, uint8_t *pData, uint16_t Size, uint32_t Timeout)
rawValue = buffer[0]<<8 | buffer[1];
//buffer[0] -- MSB
//buffer[1] -- LSB
printf("This is from ST LIS2DE12 : %s",rawValue);
//printf("\r\n");
//printf("%s",result);
HAL_Delay(1000);
Any clues ?
Thanks
