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I2C SDA pin broken?

TNils.1
Associate II

Hi

I am trying to configure I2C2 on an STM32F405RG on pins PB10/SCL and PB11/SDA, but I am getting very strange output on SDA.

STM32 is I2C master. Using I2C example from STM32F4-Discovery folder.

Using 4k7 ohm pull-ups to 3.3V.

Is the output pin broken, or what could I have missed?

Top is SCL and Bottom is SDA, trying to initiate communication repeatedly,

0693W000003Q3SRQA0.jpg

I would have tried I2C1 instead but the MCU is on a custom PCB and those pins are already occupied.

1 ACCEPTED SOLUTION

Accepted Solutions
TNils.1
Associate II

Thanks! Some times you just don't think about the obvious. Probe adjustment issue . Of course :)

View solution in original post

3 REPLIES 3
TNils.1
Associate II

Ok, so I patched the board and tried I2C1 on PB8 and 9 instead.

Exact same behaviour. So clearly something is wrong.

I am trying to run the STM32Cube_FW_F4_V1.25.0\Projects\STM32F4-Discovery\Examples\I2C\I2C_TwoBoards_ComPolling example downloaded the other day.

Any ideas?

Thanks!

Bad solder joint? Broken wire? Try measuring directly at the pin, try to wiggle the pin as GPIO output, try measuring the same signal with both probes.

JW

TNils.1
Associate II

Thanks! Some times you just don't think about the obvious. Probe adjustment issue . Of course :)