Garbled Serial from Arduino and NFC Shield

As a project I built my own Arduino UNO. As of right now I can load sketches via the ICSP port for the 328P. Flip says it loaded the bootloader for the 16U2. I don't know how to verify this but since the computer picks up the UNO when I connect via USB I assume it loaded correctly.

This is where I get lost. If I can load the bootloader to the 16U2 via USB why does the serial monitor receive a garbled message when I connect the NFC shield. Attached is the image of the received message.

The message I should be receiving is, "Looking for PN532...". This is from the example sketch provided in the NFC library.

I tried the loopback test once and the serial monitor crashed so I haven't tried it again.

I would be greatly appreciative if anyone can provide some help.

Thank you.

Sam

Looks like the wrong baud rate on the serial port.

That's what I thought as well. But I have tried every Baud rate selectable in the serial monitor and tried the next lower Baud rate in the code itself and they all show up this way.

Forget testing the other stuff...

Load a bootloader on the Atmega328, set for the frequency of the chip setup on the board.

Then try the blink sketch, then try something serial that does not rely on the NFC, and lets see if the serial works first...

ChilliTronix:
Forget testing the other stuff...

Load a bootloader on the Atmega328, set for the frequency of the chip setup on the board.

Then try the blink sketch, then try something serial that does not rely on the NFC, and lets see if the serial works first...

I loaded blink with the tinyUSB. It seems to work fine. I then loaded a Serial echo sketch and the attached is what I get.

That is really odd. Can you post a schematic?

ChilliTronix:
That is really odd. Can you post a schematic?

As requested.

What value of crystal is attached to the Atmega328P?

Why is there a 10MOhm resistor across it?

ChilliTronix:
What value of crystal is attached to the Atmega328P?

Why is there a 10MOhm resistor across it?

There is a 16MHz crystal on the 328P. There is a 1M Ohm resistor because I saw that setup in the reference design.

Datasheet

Edit: I just checked, it's also there in the arduino schematic.

I see. A resistor their is not usually in the breadboard Uno's I have either seen or built. Can you try without?

Unfortunately, I made my board all SMD components. Taking them off and putting them back on is not really feasible.

It is feasible, it's just awkward...

Did you try prototyping it first?