Hi!
I've been trying to make my own board with a SAM3X and W5500 (Arduino Ethernet Shield) on it with those two chips connected via SPI.
From the Arduino Due Board, most of the stuff, we don't need. So obviously, almost everything went off. Particularly, I remove the power switching circuits since we won't be varying power anyway. The native USB Programming also went off as well as the Programming port circuit.
I've only left headers so I can connect the 16U2 (with 16MHz crystal) circuit externally. Headers are VIN (5V from USB), RX (from a level shifter), TX and Ground. I'd not included the reset signal so from the 16U2 pin, I connected a 1kohm resistor (R23) to the reset line in my board.
The 16U2 I have externally is programmed with the new file in
When I connect the 16U2 circuit to my USB Port, I was able to see it as the programming port correctly. However, when I try uploading a sketch to the board (sample blink), the IDE says No Device Found on the COM port.
I've tried using bossac and modifying the COM port thru command prompt but I still get the same result.
I've checked the SAM3X checklist and it says there that for SAM-BA to boot, I only need to have the correct supplies and the 12 MHz Crystal Oscillator. I've checked everything using multitester and all the supplies are in the correct voltage. I've checked the crystal using an oscilloscope and I can see that it outputs the expected waveform.
I've also checked the TX and RX line from the 16U2. There are data being send by the 16U2 but the SAM3X is not responding.
One thing I notice is that the 32 kHz crystal is not working. But from what I've read in these forum, that is not powered by the SAM3X until the slow clock oscillator is enabled to be externally sourced.
The last thing I think that I've done different is that I'd connected the VBUS pin to the 3.3V supply rail where it was directly connected to the USB power. The reason I've done this is because I'm not using USB anyway.
Also, the data lines for the native USB, I've terminated them using 1MHz resistors to ground just so they're not left flaoting.
Are these (VBUS and datalines) causing my SAM3X to not reply and properly work so sketches can be uploaded? Would want to confirm VBUS first before destroying the trace in my board as I'm afraid I might fry the SAM3X chip with 5V.
Are there other things I've done wrong?
sam3x_bp2_v0p1.pdf (993 KB)