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1  Using Arduino / Microcontrollers / Re: Micro - Power-up behaviour different? on: April 20, 2014, 02:15:57 am
Thanks all for the answers.
@bobnova - I hope originals are sold at Conrad, the boards and their packing look OK.
@paul__b - Did not know that it is possible or how to read the existing bootloader version of a board. I have already programmed bootloaders on "naked" processors.
So I will have to do some investigation and try new and/or old firmware.
2  Using Arduino / Microcontrollers / SOLVED Micro - Power-up behaviour different? on: April 19, 2014, 09:11:01 am
I have three Arduino Micros. One is behaving as expected - it starts the application program immediately after power is applied.
I tested the same at a second Micro and was surprized to see, that it is obviously first running the bootloader after power up, which causes an unwanted delay of several seconds for the application to start. My third Micro also delays to start. This behaviour is the same, either powered per USB (only 5V supply or from PC-USB) - or Vin. I have not access to the first board any more and don't know its revision, the other two missbehaving are R3.
From the specification, the Micro should start the program immediately, the bootloader should be initiated only after a reset or when initalized for programming via USB.
The reset pin is not connected, trying to keep the reset pin additionally puuled up with a 1k resistor as a test does not help.
Any ideas?

After updating the bootloader from the current Arduino IDE 1.0.5-r2, the application sketch is starting immediately after power up.
3  Using Arduino / Installation & Troubleshooting / WARNING: New arLCD - Version mismatch on: April 09, 2014, 01:41:04 am
As maybe one of the first users of the EarthMake-arLCD out of "Arduino AtHeart", I want to share my current experince with the installation and warn: Do not follow the QuickStartup guide as it is currently (April 2014) publiched at the product page!
I bought two of the arLCDs and followed the Quick startup guide, in the errenous believe to "update" the software and install the latest drivers.
After not getting any success with programming the UNO section of arLCD I did a lot of research - the result (as I found in comparison with my second arLCD) is:
Currently the arLCD has the latest Version 2.11 of the software already installed and also present in the flash drive, so do not update it as recommended from the the downloads as this is leading to a downgrade to V 2.10 which did not work for me. It was quite difficult to find the current V2.11 Firmware file at Github to reinstall the most current system on my arLCD by copying the files from the second unit, but now it is running well.
After unpacking your new arLCD proceed as follows:
After installation of the driver as it is present in the flash drive, just use the ezARDLib as you find it in the original flash files, use Arduino1.05 as UI, Programmer "AVRISP mkII", "UNO" as board and the correct port setting.
4  Using Arduino / Programming Questions / Re: Send a negative data on: April 06, 2013, 10:28:38 am
Usually, negative numbers (integers) are determined by setting the highest bit to 1.
5  Products / Arduino Due / Re: Problems reading an analog input and output with 12 bits resolution on: February 24, 2013, 09:26:56 am
If you need the output voltage starting from zero, you might compensate that by usage of a diode which shifts the min. as well the max. voltage by approx. -0.7V giving you a range of ~0..2V.
The ADCs work in full range 0..3300mV = 0..4095. There is only a slight variation for the upper limit, as the reference Voltage at AREF is built from the DUE's 3,3V regulator which is not that accurate in the range of some mV. You can apply your own AREF-voltage, but have to modify the hardware (remove a resistor) for that. AREF is not selectable by software at the DUE.
Further I found the ADC not to react below 13mV (which causes a small offset) and also the temperature issue I already reported before - that could cause a significant missreading.
6  Products / Arduino Due / Re: Problems reading an analog input and output with 12 bits resolution on: February 23, 2013, 12:10:51 pm
thank you for your reply.
For me it was necessary to use mapping, to be able to obtain the correct voltage relation (as to your project) in the limited outout range my Dues provide. It could have been completely done in one step with "map", but for better understanding I used your multiplicator as first step to translate the input by 1.625 and the used map to obtain the correct voltage from the DAC as I found that not to be 1:1 (the value read for xV from ADC input did not result in xV when fed to DAC).
Are you able to set the voltage of the ADC-outputs in the full range from 0.0 to 3.3V !?
This would be different to what I and also others found.
7  Products / Arduino Due / Re: Confusion as to which header to use for SPI on Due - ICSP or SPI on: February 21, 2013, 06:01:41 am
attention to not exceed 3.3V at the pins of the Due (SPI-2 is connected to +5V).
A valuable source in such cases is: where you can solve the puzzle - what is connected to what.
I think the confusion SPI/ICSP is caused by the common ISP-library documentation with was issued for the standard Arduino boards - there is not yet a hint for the different labels at the Due.
8  Products / Arduino Due / Re: Problems reading an analog input and output with 12 bits resolution on: February 20, 2013, 12:27:33 pm
it is not just clear if you still have a problem, what the problem is or if you already could solve it.
In case you solved it - what have been your findings and why was it "just necessary to write this" (might be of interest or help for others).
9  Products / Arduino Due / Re: How to you write to the second DAC? on: February 18, 2013, 06:34:40 am
From my experience and as documented:
The two DAC output are addressed as DAC0 and DAC1!
Unfortunately the common description of the board functions mentions DAC1 and DAC2 which might lead to misunderstandings.
both DAC seem to work only in a range of 1/6 .. 5/6 (0.55..2.75V) of the max. voltage of 3300mV
10  Products / Arduino Due / Re: Problems reading an analog input and output with 12 bits resolution on: February 18, 2013, 02:46:55 am
There are still some issues with the ADC and DAC.
I found and reported earlier, that the ADC readings drop as soon the ARM is warming up a bit (>32*C).
The DAC is obviously outputting voltages only in the range of 1/6..5/6 of 3300mV -
see also postings at:,129765.15.html
I have modified your code as follows which should work with above limitations:

Read the value of the potentiometer (1.000V) at A0 and multiply
for 1.625 and output it at DAC1 both with 12 bits resolution
unsigned long val = 0; // variable to store the value coming from A0
unsigned long val2 = 0;
unsigned long outputValue =0;
int analogInPin = 0; // Analog input pin connected to the variable resistor
void setup()
  analogReadResolution(12); //read-resolution to be set first
  analogWriteResolution(12); //this should not apply according to documentation but surprisingly does not show up as error?
void loop() {
  val = analogRead(analogInPin); // read the voltage on the pot
  val2=val*1625/1000; //recommended and faster to use integers instead of float for calculations.
  outputValue = map(val2,550,2750,0,3300); //to normalize limited output range
  analogWrite(DAC1,outputValue); //write at DAC1
11  Products / Arduino Due / Re: I/O loading on Due on: February 14, 2013, 03:32:06 am
What you might have overseen: On the same page of the data sheet you mentioned, the currents for the GPIO inputs with non activated resistors for pull-up/down are specified as Leakage current in the range of 2 to 30nA. This should answer your question for the load.
In case of activated resistors - for the Due I expect only the pullup mode to be implemented, although the specification for the Arm obviously also allows a pulldown mode >edit: - pulldown only for TST,ERASE and JTAGSEL<.
12  Products / Arduino Due / Re: DUE - ADC shows strange drop depending on °C and timing on: February 13, 2013, 09:29:13 am
thank you for your reply.
the 2V battery was the initial object to be measured at the analog pin, the power was supplied by USB-5V!
After first indications of incorrect results in measurement, I simplified the circuit to only test with a resistor-divider (as described below) for analog measurement and USB-5V supply, over which also the result of the measurements is shown via the serial monitor at the PC (serial.print).
The unexpected thing is, that the readings drop as described in my previous postings and after a Due-reset or restart of the serial monitor (which also restarts the Due) the first readings are correct again, before the measurements drop again to sigificantly smaller wrong values. For me, this is an indication that there is something wrong with the analogRead command, not a hardware problem.

It would be helpfull if someone could confirm. The only hardware needed for a test is a resistor of approx 2k-ohm connected from 3,3V to A0 and a second resistor of half size from GND to A0. This circuit will apply approx 1,1V to A0 (1/3 of 3,3V). Running my test-program should demonstrate the problem at the serial monitor.
13  Products / Arduino Due / Re: DUE - ADC shows strange drop depending on °C and timing on: February 12, 2013, 10:01:30 am
Today I received a brand new DUE and tested it very carefully with minimum necessary connections (to avoid any damage). I used latest software v1.5.2.
Unfortunately it still shows the same buggy behaviour which confirms my earlier findings:
The temperature reading on an anlog pin is significantly dropping due to rising die temperature of the processor if the reading is executed after a pause of more than approx 1 second. As soon a cool heat sink is placed directly to the surface of the processor, the readings return to correct values. It is possible to minimize this weird behaviour by executing a series of dummy readings immediately before a final undelayed measurement.
All useres who depend on reliable readings from the analog pins should be warned and take counter measures!
14  Products / Arduino Due / Re: DUE problem with micros() inside interrupts on: February 11, 2013, 02:20:47 am
In such cases and for test purposes I prefer to change an output pin to be minimum invasive (compared the used serial command).
Invert an output inside- and each time the interrupt is called and watch the result with an oszilloscope, logic analizer etc. The comparison between the input signal and the output should show you if the interrupt is missing something.
Another solution might be to use two counters. One inside the interrupt and a second one outside (at this frequency the signal will be detected easily also not using an interrupt). If both count up at the same rate - it should be OK.
I hope I could help.
15  Products / Arduino Due / Re: DUE - ADC shows strange drop depending on °C and timing on: February 08, 2013, 05:10:35 am
thank you very much for your hint.
I had well checked the SAM-datasheet but saw only the ADC-section - not these remarks.
Obviously the tendency is similar, but what I found seems to be a different misbehaviour. It is depending on temperature and occurs much faster (only approx. 1000ms after a read-pause). After a restart the first readings seem to be OK and than drop to constant wrong value - opposite to above SAM description.
"Dummy conversions" as a workaround I found by experimenting too, but don't seem to solve this problem clean and completely.
Maybe my two boards are defective or a bad implementation of the analogRead command?
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