pc8574 interfacing with stm32f103c8

[Elango]

Hi,while interfacing pc8574t with stm 32  i2c communication after generating start condition and sending slave address (0x4e) as in datasheet acknowledge failure flag was enable  this was the waveform i got and still can't find what could be reason it

if any suggestions please let me knowi2c waveform

[TDK]

SCL should be toggling.

Some possibilities:

• Pin isn't configured correctly.
• Something else is pulling SCL high. Consider doing an analog capture at a high sample rate to see if voltage drops at all when SCL should be going low.
• Probe isn't connected to the pin.

[Elango]

hi sir, i checked it it seems to be a pin connection and i sort it out now after sending start bit it transmits stop bit 

i have attached photo below

while debugging i came to know it generates start condition after sending slave address the AF(ack failure) flag was set and stop bit was generated

[Elango]

and also add on to that while debugging i saw it doesn't generate start on first transfer it generates restart condition 

i have attached photo for better understanding(the green colour statements are the one which conditions satisified)

[TDK]

Looks like you're just missing edges due to insufficient sample rate. Increase the sampling rate on your logic analyzer.