USART communication between stm32f407 and two stm32f030

[sanjib]

Posted on January 21, 2015 at 09:55

HI ALL

I have written a code for USART communication  full duplex between stm32f407 and stm32f030 and it is working fine as soon as power on reset. The half duplex communication also working fine between two stm32f030 as soon as the power on reset. BUT IF i connected the three together The logic is f407 sends some cmd to 1st f030 through full duplex usart, after receiving that the 1st f030 send that data to 2nd f030 , the 2nd f030 processed the receives data and send back the process cmp ack to 1st f030 and 1st f030 sends the same ack to f407...and the loop continues..... The issue is ,it doesn't happen in power on reset It happens after presseing the reset button of f407 (as f407 is master) for 8 times , always 8 times after that everything works fine but not in the 1st power on reset. I have debugged and I have seen that there is a frame error in the 2nd  f030 when the first packet is received. after 8 times reset packet is received fine(ther is no frame error) I have checked sending the received data of the 2nd f030 to the hyper terminal through the other USART.... Why it is working fine after 8 times reset but not in the first time....Can anybody face this issue. Please help

[ivani]

Posted on January 24, 2015 at 11:37 The internal pullup on the Rx pin should be sufficient. It is necessary because the output of half-duplex receiver goes in a high-impedance state while the receiver is disabled.

[Tesla DeLorean]

Posted on January 24, 2015 at 19:28

Your description really doesn't help me understand the failure, I seriously doubt the hardware is keeping track of the number of resets you are performing.

What would be helpful is diagrams for what data packets are sent by whom, what is received, the time line of which these occur, and scope/analyzer output annotated with descriptions of what's happening, and markers of where the errors are observed, and the data received vs transmitted.