HAL_I2C_Master_Sequential_Transmit_IT doesnt return data in data buffer

[ABah.1]

Hi all

I want to read i2c data of bme280 sensor. I must read it sequential as follows:

​

Start

Slave address ack

Internal register address Ack

​Repeated start

Slaveaddress ack

Data to read

Stop

​

​

​I do that and every thing is ok in logic onalyzer. For example chip id is read correctly in logic analyzer but HAL_I2C_Master_Sequential_Transmit_IT function does not update data in recieve buffer.

How can i solve this problem??

[TDK]

HAL_I2C_Master_Sequential_Transmit_IT is a transmit function. It doesn't receive data.

You'll need to use HAL_I2C_Master_Seq_Receive_IT to receive data.

If you still have issues, post your code and logic analyzer data.

[ABah.1]

Yes youre right and i had used recieve function. My code image and osciloscope data are attached as you seen in oscope data i am reading 0x60 as id of bme280 sensor which is correct but it is not updated in Rdata buffer

[ABah.1]

Oscope data

[Piranha]

For register reading one must use HAL_I2C_Mem_Read...(), not those separate functions, which put stop bit in the middle of transfer.

[ABah.1]

I should use the following relation to read data

Start

Slave addr

Internal reg addr

Repeated start

Slave addr

Reading n byte

Stop

​

Beacau oof need to repeat start i have used sequential functions which are ok.

Hal_i2c_mem_read doesnt support above hirerchy

[Piranha]

You're wrong - it does it all in a single call because that's the whole purpose of that function!

[ABah.1]

Could you please write me the format which i must use from. Hal_i2c_mem_read for use in repeat start mode

[Piranha]

Just use HAL_I2C_Mem_Read_IT() to read the device registers. It's not even clear what you cannot understand here...

[ABah.1]

I can understand but it generates stop. However we need repeat start.

Bad answer

[Piranha]

I already said multiple times that it does not generate STOP condition in the middle and does exactly what you and 99% use cases need. Enable the cerebellar cortex feature!