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1  Products / Arduino Due / Re: reliable startup? on: March 06, 2013, 02:08:38 pm
good to hear i am not the only one having this problem. i did fix it with the power on reset chip but would really like to know if there is a fix by configuring the brownout detector on the microcontroller. this is the only microcontroller board i have had this problem with.
2  Products / Arduino Due / Re: reliable startup? on: March 03, 2013, 12:51:16 pm
i don't which voltage you use for triggering the POR chip is that important. all that is important is that you reset the microcontroller after a reasonable delay after power is applied. of course you need a voltage that matches the threshold of the device. they come in a few different thresholds to work with 3.3 5 and maybe other voltages. i use a fairly large capacitor for a long delay just to be sure. it has worked absolutely reliable. i used a dip version but i am sure you can get surface mount if space is a problem and use a tantalum cap if there is no room for an electrolytic for the timing cap. make sure the POR chip never sees sense voltage without its power supply connected. i made a shield with some of those crappy thin pin stackable headers that came with the dev shield and a bad connection to 3.3 volts killed the POR chip. not much of a loss but a waste of time figuring out why it didn't work. since then i found some better square pin stackable headers.

it seems to me that this startup problem is a bug with the DUE. are there any configuration options that might fix this in the microcontroller instead of forcing us to add POR chips?
3  Products / Arduino Due / Re: Due pinout diagram on: February 25, 2013, 10:39:06 pm
quite readable now on my color laser printer. thanks for lightening up the blue. in fact, it looks just like the version i modified in photoshop.
4  Products / Arduino Due / Re: Using the Hardware Quadrature Encoder Channel on the DUE on: February 20, 2013, 04:17:14 pm
the buffer is a better way but i am using my 5 volt encoders with a voltage divider on the output. just a 10k and 20k resistor in series. easier to stick in as an afterthought than wiring in the buffer.
5  Products / Arduino Due / Re: Using the Hardware Quadrature Encoder Channel on the DUE on: February 20, 2013, 03:22:41 pm
i don't know if you can do it fast enough for high speed operation but the last encoders i bought (made by Bourns) have a chip select line so you could conceivably stick them all on a bus and sweep through them looking for signal changes. the programming might get a little confusing or might even be impossible.
6  Products / Arduino Due / Re: program upload issues on: February 15, 2013, 06:31:30 pm
i do not use folders with special characters or spaces. i have done enough windows programming to avoid them like the plague. the default folder when the IDE was unzipped did have some .s and -s in it. i removed the .s and changed the -s to _s. nothing but letters and _s now. do you consider _s to be special characters? the optimization is not working. loading the same program right after doing it once and changing nothing, the compile still happens.

so still hoping for something that will help solve this problem. i am going to add an external erase switch.

does anyone who is reporting no problems like this use win 7?
7  Products / Arduino Due / Re: program upload issues on: February 15, 2013, 05:40:25 pm
i am definitely using the programming port. i have determined that i need to press reset to make sure that either the loaded program is running or that memory is erased. then i need to press reset again before loading the program. if i upload a program and the comport not found error occurs, the memory has in fact been erased because the program is no longer there. so there really is communication via the serial port to erase the memory. it seems that two attempts are needed each time, one to erase memory and one to program. if i press the erase button manually, i can then press reset once and succeed at uploading every time.

i have two different boards and both behave the same. they have different stuff connected and different programs. on one, the erase button is accessible so it was no big deal.

i don't mind pressing reset several times and attempting to upload a couple of times. what kills me is having to wait to compile and verify the program only to find it will not upload. IS THERE SOME WAY TO JUST UPLOAD THE LAST COMPILED PROGRAM AND NOT HAVE TO RECOMPILE?

also, what do you mean by have a look at the USB port? what should i be looking for?  also what should i be looking for in terms of hardware on the board? i have two boards that behave the same so i doubt it is a mfg error unless it is a problem with a run of boards that all have the same problem. i bought both of them from Digikey in fairly close succession so maybe they are of the same batch.
8  Products / Arduino Due / Re: program upload issues on: February 15, 2013, 04:27:24 pm
the only explanation i can find about programming the DUE from the Arduino IDE is the following. it clearly says that the 16U2 is supposed to do whatever is needed to insure programming. what exactly is meant by "Opening and closing the Programming port connected at 1200bps" ? where do you set the programming speed, in the serial monitor speed selection or is it always at 1200 bps? what is meant by opening and closing? do you have to de-select the port and re-select it or is there some other secret? unplug and replug?

i don't understand why something so basic is so badly documented.

Programming port: To use this port, select "Arduino Due (Programming Port)" as your board in the Arduino IDE. Connect the Due's programming port (the one closest to the DC power jack) to your computer. The programming port uses the 16U2 as a USB-to-serial chip connected to the first UART of the SAM3X (RX0 and TX0). The 16U2 has two pins connected to the Reset and Erase pins of the SAM3X. Opening and closing the Programming port connected at 1200bps triggers a “hard erase” procedure of the SAM3X chip, activating the Erase and Reset pins on the SAM3X before communicating with the UART. This is the recommended port for programming the Due. It is more reliable than the "soft erase" that occurs on the Native port, and it should work even if the main MCU has crashed.
9  Products / Arduino Due / Re: program upload issues on: February 15, 2013, 03:56:45 pm
actually, it shows the last connection. there is no guarantee that the DUE will connect if the right sequence of buttons is not pressed. it is not a problem of not having the right port selected. it is a problem with getting the DUE to be recognized without an impossible or difficult to reproduce sequence of button presses.

this really should not have to be difficult. the teensy is the most friendly in this regard. there is a single button to press that loads the last compiled program. a single button, is all it takes.

i am going to bring the erase button out of the board so i don't have to deal with this but it really is something that could be handled better in both the bootloader firmware and the IDE.
10  Products / Arduino Due / program upload issues on: February 15, 2013, 01:21:21 pm
i have a stack of shields on top of the DUE and can not get to the erase button. i have not quite figured out the mysterious combination of button presses that reliably allows uploading a new program. previously i would press the erase button and then reset and it worked reliably. since i can not get to the erase button now, i can some times succeed with various combinations of short and long presses of the reset button alone. i have not yet discovered exactly how long to wait and how many times to press etc.

if the program does not load successfully, the error message is that the com port is not found. then i do some random reset button pressing and it usually works the next time.

if the IDE were to check for the com port before compiling the code, this would save a lot of time. the way it is now, i have to wait for the successful compilation each time only to be told the com port is not there. is there some way to attempt to load the program without re-compiling each time? if not, i highly recommend that the IDE be modified to allow this or to check the com port first before compiling a program that can't be loaded.

or, is the best solution to bring out the erase button? unfortunately it does not seem to be on any pins that carry through to the shields so i would have to solder on a new button and let it dangle somewhere. it would certainly be nice if the button were more accessible or brought out on some pins or if erase was done by firmware when loading a program as part of the load sequence.

any ideas on how to make this work better?
11  Products / Arduino Due / Re: Using the Hardware Quadrature Encoder Channel on the DUE on: February 14, 2013, 12:57:50 pm
so for us dummies, does this code print the accumulated count from quadrature input on digital pins 2 and 13? not too good at complicated datasheets. also, are there only two pins that can be used as quadrature input and are they D2 and D13? i have a TFT shield that is wired to pin 2 among many others and can probably cut and jump to make pin 2 available but would prefer to not. my not very good interpretation of the data sheets suggests that three timers are available for quad processing but only two are brought out on the DUE board. is this correct?
The Timer Counter (TC) embeds a quadrature decoder logic connected in front of the 3 timers

and driven by TIOA0, TIOB0 and TIOA1 inputs. When enabled, the quadrature decoder per-
forms the input lines filtering, decoding of quadrature signals and connects to the
3 timers/counters in order to read the position and speed of the motor through user interface.
12  Products / Arduino Due / Re: shield layout for DUE/Mega on: February 13, 2013, 04:11:41 pm
any help in this regard would be appreciated. i would like to print out bout layouts to a large scale and see if they register. my printer seems to not be totally accurate so i can not print out board sized registration check sheets. i will check out Kicad. please send me the layouts for DUE or tell me where to get them. also any links for kicad would be appreciated in case i can't find them. you can e-mail the files to
13  Products / Arduino Due / Re: shield layout for DUE/Mega on: February 13, 2013, 01:26:58 am
because i am too cheap to buy Eagle and too lazy to learn to use it. i am making the general purpose shield but will only have it made once i add additional circuits. i need to cram a lot on (a POR chip, quadrature decoder, SD card socket in an accessible position, screw terminals and an auxiliary microcontroller) and don't want to do a lot of point to point wiring. i have some dev shields on the way and will use these for prototyping but once i figure out what i need, i will copy the circuit to the general purpose layout.

the project i am working on needs to have a lot of stuff between the DUE and a TFT shield. i can probably fit it all on both sides of the dev shield but don't want to wire another board once the proto is working.
14  Products / Arduino Due / shield layout for DUE/Mega on: February 12, 2013, 09:24:07 pm
I am drawing a general purpose shield for the DUE/Mega using ExpressPCB. Eagle files are available for the boards as well as for several shields but I do not have Eagle. Can someone please verify that all of the headers are on .1" centers with two exceptions. the ICSP header seems to be off grid. the header for digital pins 8-13 and Aref etc is off by .05" its the adjacent pins on this and the header  with digital pins 0-7 are .15" apart instead of .2" as with the case with all other adjacent headers. the SPI header is on .1" grid
15  Products / Arduino Due / Re: reliable startup? on: February 08, 2013, 03:16:05 am
i connected a TLC7705IP as a power on reset and it fixed the starup problem. i used the 7705 which ihas a voltage threshold of something like 4.6 volts. it is powered by the 3.3 volt supply so its logic levels are 3.3 volt compatible but it has the sense line on the 5 volt supply. i had to use a large timing capacitor of 4.7 mf to hold the reset high for something like .5 seconds. anything much shorter does not work.

i do think that this should not happen with the DUE board. it should properly use the various brownout and startup capabilities of the SAM micro. it is not a big deal to add this chip but the board is supposed to be a working system and have these details worked out. i hope future revisions of the board do not have this problem. otherwise i am very pleased with the DUE.
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