To make a very long story short I've designed a custom board and it flat out will not work. I cannot connect the USBTiny programmer I have to read fuses despite readily being able to read a Arduino Pro.
The board is powered by 3.3 V running a Atmega 328P at 12.0 megahertz via a Murata resonator.
Microprocessor Link
Resonator Link
I've included an image of the schematic with accompanying MPU-6050 on the odd chance there is a conflict. The board itself has been gone over circuit by circuit to verify that there are no errors when compared to the schematic.
Not one to roll over and give up without a fight I've done about all of the diagnosing I know how. I've tried programing the board in 5v from the programmer (left voltage regulator and mpu-6050 unpopulated).
Really dumbfounded on this, any help would be greatly appreciated.
When you install the bootloader and set the fuses, the Programmer needs to be able to control the Reset line directly.
Jumper across C8 and try it.
You should also have more 0.1uF decoupling caps on the VCC/AVCC pins. I only see one for the entire board.
What do Rx & Tx connect to?
White/yellow on black background is very hard to read. Next time post with black on white.
I will jumper C8 and see if that works.
There are two 0.1 uF caps but I will look into adding a couple more, as well as some larger values for lower frequency noise. This was a first pass with relatively clean DC power so I didn't do as much homework in that area as I should have.
RX and TX go to header pins, they were added when I realized I have a problem. In the current board I don't have access to them, however new boards are being fabricated as we speak. As you can see I've added them on all of the critical circuits, rookie move not to have them in there to begin with.
Success, sort of, I am still unable to program the board when running on internal 3.3V power. If I power the board externally at 5V it will program and run a blinker program. If I switch back to 3.3V the board will run the program as expected.
With the MPU-6050 only rated for a little over 3.3V I need to figure that out. Having the board up and running (even partially) is a relief though. This is my first design, first schematic, first board layout, and first bill of materials, the fact that it didn't go up in smoke is a small miracle.
