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STM32F746G-DISCO problems with the internal I2C on CN7

I have many problems using the CN7 connector (pin SDA/SCL) with external I2C FRAM and I2C DAC chip.

There are no problem using the EXT/RF E2P connector (pin EXT_SDA/EXT_SCL).

Why ?

5 REPLIES 5

Isn't there some internal connection on those "problematic" pins? Check the DISCO schematics/user manual.

JW

> I have many problems using the CN7 connector (pin SDA/SCL)

There are two pairs of SDA/SCL on that connector. Which exactly do you use?

How do you set the relevant solder bridges (SB1, SB3, SB4, SB5)?

Do you have anything connected on P1 (camera) connector?

JW

On the CN7 connector (Arduino style) there are 2 pin I2C1_SC and I2C1_SDA (PB8 and PB9).

Using these pins many times the I2C lock during receive or get bad data.

If I use the EXT/RF E2P connector (pin EXT_SDA/EXT_SCL) there are no problems, why ?

The SB pin should be in the default configuration

0693W000000V4U7QAK.jpg

No other connections to these pins

I2C1_SCL PB8 D15 10

I2C1_SDA PB9 D14 9

A4PF7 or PB(1) ADC3_IN5 (PF7) or I2C1_SDA (PB9) USART6_TX PC6 D1 2

A5PF6 or PB8(1) ADC3_IN4 (PC0) or I2C1_SCL (PB8)