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7 years, 9 months ago.
I2C VERY low frequency on SDA
Hello everyone,
I just got my NUCLEOF103RD and started to program today. I was able to use the general I/Os both with mbed and Keil MDK 5 and also got the USART to work in both environments, I am trying to get I2C to work.
The strange thing is, that the SCL pin is running normal frequency, the SDA Pin is running slower than 1Hz!
It is ridiculous really.
I have flashed the i2c_master example from ST as well as trying to use HAL directly and just sending 0x68 over the bus. I does not matter what I do, the frequency is always really low.
I am using 4k7 Pullups and a Rigol Oscilloscope.
I have tried, what I think, is everything.
Thanks in advance
Chris
I solved it, and I feel very stupid. I am used to working with "dumb" 8bit ATMegas. There you can give the SDA and SCL line a pullup, or you don't, and still measure the correct clock/data. Apparently the STM is more intelligent. Also maybe more intelligent then me...
I only connected one Pullup and, as far as I can tell, the STM noticed that the SCL Pin would not go HIGH. It tried to synchronize and eventually hit a timeout. That is very, very long as it seems.
So... I was just being stupid...
posted by Christoph Deussen 09 Aug 2016