I built my own Arduino Uno. I designed the schematic and laid out the PCB for a school project. I am having problems getting the serial communication to work so that I can program sketches. Here are pictures from Pin0 and Pin1 of the headers (Rx and Tx) when I send information using an Echo sketch. I programmed the sketch using the ICSP.



What can I do to fix my issue?

Below are screenshots of the code and the serial monitor before and after I send a message.



When I took the pictures I sent a long random message so that I had time to freeze the scope.

Here is the schematic I made:


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    \$\begingroup\$ I'm having trouble understanding what the scope shots mean. What are the bytes you are actually sending? What bytes are you receiving on the receiver terminal? Can you post your code and your circuit schematics? \$\endgroup\$ – Ricardo Dec 7 '14 at 22:12
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    \$\begingroup\$ And what is the exact issue you are referring to? What do you expect to see, what do you consider wrong in the scope traces? Is your scope AC coupled by any chance? \$\endgroup\$ – jippie Dec 7 '14 at 22:20
  • \$\begingroup\$ That looks to me like the scope's ground isn't connected to the Arduino? Also, do you have it set to AC coupled by any chance? \$\endgroup\$ – Majenko Dec 7 '14 at 22:25
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    \$\begingroup\$ First check the scope probe calibration... \$\endgroup\$ – Brian Drummond Dec 7 '14 at 22:29
  • \$\begingroup\$ @Ricardo I sent a random message so that I could freeze the scope. I think the requester of the images thought there might be noise or something on the line. Original post updated to include all the requested materials. \$\endgroup\$ – user1362058 Dec 7 '14 at 22:41

Through the chat we found out the problem. The Atmega16U2 did not have the fuses set to use the external clock. This was causing the 16U2 to divide the input baud rate by 8.

Thank you Connor for helping solve this problem.


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