NUCLEO-F401RE UART not showing up on logic analyser via pins

[BadEngineer]

I am using a Nucleo-F401RE and wanted to look at the UART section. Ideally i wanted to see the pins go up and down to see what they are doing. 

I am using huart1 so the transmit is on PA9 and receive is on PA10. I've hooked up the logic analyzer to PA9 and PA10. To ground the logic analyser i am using pin number 7 on the CN6 connector. 

Below is what the logic analyzer is showing. It seems like it is very intermittent. When i am debugging it and get to the stage where it needs to send a signal out, nothing shows up. If i run it continuously i can see the pin fluctuate. 

What am i doing wrong? 

 

 

My Code is rather simple.

 

 

 

 

[Karl Yamashita]

It looks like a basic transmit. Though you should be using strlen((char*)p_str) instead of hardcoding the number 15 because the string length changes.

If you use the VCP( UART2), do you see your string using something like Putty or Docklight? 

 

[BadEngineer]

Hi Karl,

 

So i've taken on board what you have said and i am not transmitting it to huart2 aswell. I can see that hello world is being transmitted onto tera term. 

However the signals from huart1 are still not showing up when running it through debug 

My code and tera term communication 

 

 

 

[Karl Yamashita]

Your code shows a comment that UART2 doesn't work. However Tera Term shows that it is working. So it looks like it's an issue with your logic analyzer?

Maybe try a basic blinking LED or GPIO pin at 1 KHz and see if the logic analyzer works picking up that signal? 

[mƎALLEm]

Hello,

Need to fine tune the timings of your logic analyzer (decrease the time scale) an set a trigger on the falling edge

[BadEngineer]

Hi SofLit, 

I wanted to make sure I wasn't going crazy, so I brought out one of my previous projects with the logic analyser. This is a simple I2C communication (using the same nucleo board) communicated with an AHT10 sensor. Below are the readings from my logic analyser (top is SCL and bottom is SDA). You can see that it works fine with I2C protocol