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1  Products / Arduino Due / Re: Programming Bare SAM3X Chip on: May 30, 2013, 04:11:27 pm

I got this working awhile back; the main things for me were to switch out that oscillator to 16 MHz, and also program the 16u2 with the correct firmware and fuse configurations  using the avrisp mkii programmer and Atmel Studio.
2  Products / Arduino Due / Re: reliable startup? on: January 31, 2013, 04:44:19 pm
This is the chip I am looking into. It has a few different packages with varying threshold voltages:

This is a relatively quick solution when the alternative is tearing out caps and resistors to reduce delays (which seems to be the issue as far as I can tell).
3  Products / Arduino Due / Re: reliable startup? on: January 31, 2013, 03:58:28 pm
I have experienced the same problem, and resetting the board always works for me. The best I've come up with is to throw on a Power-on reset IC to automate that process for me, but have yet to find the real hardware issue with this.
4  Products / Arduino Due / Re: SerialUSB RX Buff Size on: January 31, 2013, 01:10:46 pm
I found a definition in the HardwareSerial.cpp file, but it is located in hardware\arduino\avr\cores\arduino. I did not see a separate .cpp for the SAM folder, so I am assuming the header HardwareSerial.h for the SAM is referencing the same source? Thoughts?
5  Products / Arduino Due / SerialUSB RX Buff Size on: January 30, 2013, 01:08:40 pm
Can anyone point me to the definition of the SerialUSB receive buffer in the DUE libraries? Thanks.
6  Products / Arduino Due / Re: Program memory erased after unplug on: January 24, 2013, 05:51:43 pm
The only thing I see in the data sheet for the SAM3X is about the external "ERASE" pin for the flash memory (which I have connected like the DUE schematic). I haven't been able to find anything about programming to prevent flash erase after power-down.

It looks like when I plug in and press the RESET button, however, the program begins to run. Any ideas if this function is performed on the DUE? Or could this be an issue with the hardware I am using, such as a capacitance issue?
7  Products / Arduino Due / Program memory erased after unplug on: January 24, 2013, 03:39:44 pm
I am having a problem with a bare SAM3X chip I am using in my design. I use the same programming schematic as the DUE, but when I unplug my board for ~1, 2 minutes, the memory is wiped and I have to re-upload my code.

Does anyone have experience with a similar problem? Or might know what this indicates about my design? Thanks.
8  Products / Arduino Due / Re: Programming methods other than USB on: December 05, 2012, 12:59:24 pm
The DUE Native Port does not use a second microcontroller interface, and it works through the Arduino IDE. It is still USB, however.
9  Products / Arduino Due / Re: Programming Bare SAM3X Chip on: December 03, 2012, 04:28:07 pm
I just noticed the DUE schematic has the crystal Y4 labeled as 12 MHz, when the board actually has a 16 MHz oscillator attached!

Switching these out fixed my driver recognition problem. Now when I try to program with the DUE programming port selected, the Arduino IDE recognizes the COM port of my device, but when uploading it gives error "no device found on COM #". My RX line is toggling at the proper voltage, but the SAM3X doesn't send a response.
10  Products / Arduino Due / Re: Programming Bare SAM3X Chip on: November 27, 2012, 08:20:01 pm
Reprogramming with the .hex file in sam\firmwares\atmega16u2 produced the same result.
11  Products / Arduino Due / Programming Bare SAM3X Chip on: November 27, 2012, 06:46:38 pm
I am having issues with uploading sketches to a bare SAM3X chip. I have my hardware configured like the USB programming port on the DUE, using an Atmega16u2 interface. I've programmed the 16u2 with the avrisp mkii programmer, with the firmware found here:

(I've also programmed it with the .hex file read directly from the DUE 16u2 chip).

Using the same steps with a DUE, I am able to install the DUE programming port driver, and upload sketches in the Arduino IDE.

With my hardware, I am getting a code 43 (unknown USB device) when plugging into my PC. When I try to load the USB driver directly (from the arduino drivers folder), it doesn't install. I've read in a couple forum posts that the SAM3X is bootloaded by Atmel, and that there is no need to bootload the chip. Since I am observing this disparity between bare SAM3X and the DUE, I am unsure if the issue is in hardware or firmware.
12  Products / Arduino Due / Re: PIO Set/Clear Frequency on: November 21, 2012, 01:46:04 pm
Thank you all for your responses, I was unaware of a method for getting the assembly from the compiler, so DuaneB that was tremendous help. Using a method similar to the post by stimmer, I was able to scope a 21 MHz signal.

And yes, I am aware of the methods for producing a reliable clock through other protocols, timers, etc. The current application is a user-controlled clocking of data in a finite state machine, I just wanted to see my max pin switching frequency.   

13  Products / Arduino Due / PIO Set/Clear Frequency on: November 20, 2012, 08:45:11 pm
I have been unsuccessful meeting the spec frequency of 35 MHz for I/O pins (Pin Group 2 on pg. 1423 of data sheet). The fastest I can get is ~2 MHz, using the below code fragment:

  PIO_SetOutput(PIOC, 0x7FFFFFFF, LOW, 0, 0);   
  //  enable writing PIO_ODSR for I/O line

void loop() {

I checked the value of my clock register REG_PMC_MCKR, and found that it should output an 84 MHz signal from PLLACK. Looking at data sheet pg. 544, the PMC Clock Diagram shows the MCK go direct into the peripheral clock. This I assume is the same signal that moves to the PIO controller, labeled "System Clock" on pg. 644.

What else do I need to set to meet the spec for Set/Clear frequency of the I/O lines? 
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