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Topic: Debugging UNO standalone - Help needed (Read 979 times) previous topic - next topic


I need some assistance figuring what the issue is with my standalone board. This is my second board, the first one was a Nano copy using the FT232RL and worked OK but I was unhappy with the sporadic enumeration of the USB. I redesigned it using Atmega16U2 just like Uno.
I am able to connect USb to the 16U2 and using FLIP I have loaded Firmware (Uno_and_USBSerial_combined.hex) and installed the driver so now it registers as Com port on my PC.
I am able to bootload the 328P using ICSP and AVRISPMK2 and loaded OPTIBOOT (optiboot_atmega328.hex).
I set fusebits as follows
This all verifies correctly.

problem is when trying to upload a sketch, I get the avrdude: stk500_getsync(): not in sync: resp=0x00 error.

With the scope I can see the reset pulse when uploading, but I do not see any data coming into RXD. It goes low for a second but I never see the data pulses coming in.
The Atmega16u2 is so hard to verify correct connection as the pads are all under the device but I assume it is correct as I can DFU bootload it. I am trying 3 boards so its not likely a solder error.
ANY suggestions of troubleshooting would be appreciated.


That's hard to tell, because there are many things that could be wrong.
The information you give is just a fraction of what would be needed to pinpoint the problem.

Did you try to use the original Uno firmware for both chips ? Does the Arduino Uno use Optiboot? I'm not sure about that.
If you did, the might be something wrong with the hardware of the ATmega16u2. Can you check that once more againgst the schematic of the Uno ?

But why not use an Arduino Uno in the first place ? It already acts as a com-port to the PC, and it is working.

Did you check out the new Arduino Leonardo ? The Arduino 1.0.1 has already examples for the Arduino Leonardo to make it behave like a keyboard of a mouse with its USB bus.


Thanks, I figured it out. I did it in AVR Studio without all the DFU mode sequences, I just erased the chip and inserted the combined .hex. It would be nice to do it through the usb port but since I am already using AVR Studio to bootload the Atmega328, its just another connection.
The reason I dont use an UNO is seen in the pic. My Uno is about the size of a nano to fit in a specific location for standalone use. When I need a display, it fits onto a motherboard that has switches, inputs and a LCD stacked on top.
Can you tell, I dont like wires? :-)


I'm glad you have a workaround.
Thanks for the photo.

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