Electronic – arduino – Garbled serial on custom Arduino Uno

arduinoserial

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.

Pin0

Pin1

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.

Before

After

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:

Schematic

Best Answer

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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The sparkfun is a bit of a hack device that doesn't actually do proper RS-232 level shifting. Instead it uses the voltages from the other end to charge capacitors to use for the sending voltages - a clever idea, but I can forsee flaws if the other end isn't sending high enough voltages...

I would recommend ditching the sparkfun and using a MAX232 or similar device to do real level shifting.

Electronic – arduino – Problem with RF transmitter/reciever and VirtualWire

The problem seems to be rather banal.

You forgot to properly set:

pinMode(13,OUTPUT);

in the setup() function.

Incidentally, your code should actually be working, with the exception that the LED state is likely constant. It should be transmitting anyways.

Further Edit:

Ok, I've dug into the virtualwire library a bit more, and I think I see the problem

Mainly, the default configuration for the VirtualWire library TX pin is pin 12.

Basically, you have connected the transmitter to the wrong pin (in the pictures, you have it connected to pin 1).

Adding a TX activity LED to the module:

_{Note that this will only work properly with vw_set_ptt_inverted(true); commented out.}

Best Answer

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Electronic – Is the SparkFun RS232 Shifter SMD faulty

Electronic – arduino – Problem with RF transmitter/reciever and VirtualWire

Further Edit:

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