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TCA9539-Q1: how to use tca9539-Q1, just use read mode help

Part Number: TCA9539-Q1
Other Parts Discussed in Thread: TCA9539

Hi, anybody

I tested tca9539-Q1.

I read datasheet of tca9539. 

So, I understand the slave address this ic 0x74 / (A1, A0 is LOW, 1110100)

and to use it only read function, 0xE9 (1110100 '1')

I just use it only read function.

P0 port 0,1,2,3,4,5

p1 Port 17,16,15,14,13

I use microcontroller stm series, using HAL library.

i2C setting is fast mode, clock speed 400kHz.

First, I send start message to slave. 

HAL_I2C_Master_Transmit(&hi2c1, 0x74, data, 16, 10);

and than after 3ms delay
HAL_I2C_Master_Receive(&hi2c1, 0x74|0x01, data, 16, 10);

but, there is no reaction.

yellow is SDA, blue is SCL. I didin't know where is start signal, where is ack, SDA signal is really descrip 0x74? 

how can I do? 

thank you.

  • The waveforms would be easier to read if channel 1 were not inverted.

    The rising edges are quite slow. Consider stronger pull-up resistors.

    The first byte is 01110101. It should be 11101001. I do not know about that HAL library, but it appears you need to use (0x74 << 1).