LCD1602+pcf8574 (I2C) and STM32F107

MHos · ‎2020-01-11

Hi all,

I have some problem with LCD1602 + pcf8574 (I2C) and STM32F107

pcf8574 operate as SLAVE.

I setup i2c in CubeMX and used this tutorial ( https://controllerstech.com/i2c-lcd-in-stm32/ ) to operate LCD, but I failed, then I write a I2C bus scanner and I found I2C device is not detected at all.

how exactly make it detect I2C device?

Tesla DeLorean · ‎2020-01-12

If the slave device is not acknowledging, you need to focus on power and connectivity issues.

Where multiple addresses are possible make sure the part is jumpered/strapped properly.

Check pin configuration and pull ups.

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MHos · ‎2020-01-12

Thanks for your response.

The power and connectivity is OK, I checked it 200 times.

But i dont know about pull ups. An article said "STM32F1 microcontrollers do not provide the ability to pull-up SDA and SCL lines. Their

GPIOs must be configured as open-drain, and two external resistors are required to pull-up

I²C lines."

Does it means I can not use my I2c part in slave mode?