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1  Using Arduino / Sensors / Re: Using analog reference for PTC readout on: July 08, 2014, 02:05:57 pm
Thanks! Do you think there is anything to improve on this circuit?

U2 creates the reference Voltage (3V) which is also supplied to the Analog Ref pin.

R1 and R2 is a Voltage devider (PT1000 and R2 2k) to measure the voltage over a short Distance (maybe 2 meter).

R6 and D1 is an overvoltage protection ( ESD and general overvoltage protection (I didnt calculate the maximum voltages/currents yet smiley-grin)

The Opamp has a gain of 2 which delivers an output voltage of 0-3V

2  Using Arduino / Sensors / Using analog reference for PTC readout on: July 07, 2014, 04:03:31 pm

Im trying to read several PTC1000 Sensors using the Arduino due.

Im supplying 3.0V to the circuit using the ADP150AUJZ, the VDD of the Due is 3.3V.

To get an even higher accuracy I could supply the 3.0V to AREF.. Is this correct?
3  Products / Arduino Due / Arduino DUE Circuit JTAG Pullup resistors on: July 07, 2014, 09:14:13 am

Why are the Pullup resistors for the JTAG in the DUE Circuit called RN1D, RN1A..... are they not placed? I don't have one here, so it would be nice if anyone could have a look on their boards smiley

Also, I plan to use the USB port, but only the Data Connection (and GND of course). In the Atmel Circuit Checklist it says to all the USB Ports "If USB Device is not used it can be left floating.".
Is there any sense connection on the VBUS pin to turn the USB connection ON/OFF?
4  Using Arduino / Programming Questions / Re: How to format data for I2C on: July 06, 2014, 02:02:01 am
Im transfering data to a Raspberry, if it changes anything...
Ill have a look into the given examples, Thanks !
5  Using Arduino / Sensors / Re: RPM Counter circuit verification on: July 06, 2014, 01:58:39 am
I just wanted to know if it works as intended or if threre is anything to improve smiley
6  Using Arduino / Sensors / RPM Counter circuit verification on: July 05, 2014, 04:09:06 am

I want to read out the RPM value of the signal attached to this post. Pulldown resistor R7 with 330 Ohm. R6 and C6 is a lowpass filter for approx. 100Hz. D2 and D3 cut the positive halfwave voltage to 1.4-2V. D1 eliminates de negative halfwave..

7  Using Arduino / Programming Questions / How to format data for I2C on: July 02, 2014, 02:33:26 pm

I have about 10 values to transfer via I2C. What is the best way to format and transfer it?
4 of these values are Temperatures ( for example 120.3, float). Since the I2C library is just transfering bytes, how do I "convert" them? multiplicating with 10 doesnt work..

3 of the values are values like 1 and 0, no problem.. (uint8_t)

3 others are values from 0 to 6000 ( uint16_t)

The uint16_t and float values are requested in an intervall of 5-7hz, the uint8_t values ~20hz...

So I will do something like this since the "onRequest" funktion doesnt allow to choose what to request
#include <Wire.h>

uint8_t values[5] = {12, 45, 87, 34, 98};

void setup()
void loop() {}

void requestEvent() {
  Wire.write("hello ");

void receiveEvent(int howMany) {
  uint8_t c;
  c =;

void datarequested(uint8_t whichbyte) {

But how to transfer values like 123.4 or 6000 ?
8  Using Arduino / Programming Questions / Re: Keeping all libraries in the Arduino sketch directory on: July 02, 2014, 10:23:39 am
Thanks, what about the folder for the library?

for example
#include ".../myFolder/myLibrary.h"

9  Using Arduino / Programming Questions / Keeping all libraries in the Arduino sketch directory on: July 01, 2014, 03:09:45 pm

I know that you are supposed to place any external libraries under the "libraries" folder of the arduino install directory, but I have a project that uses several libraries that I have created for the project and mainly to keep all that code self contained and out of the main pde file. However, I have tried to place the libraries in the same directory as the main PDE file so that I can more easily keep everything synced up in subversion (I work on this on multiple computers) and I don't want to have to keep going back and syncing up the libraries separately. Also, just for the sake of being able to easily zip of the sketch folder and know that it contains everything it needs.

So, is this possible anyhow?
10  Using Arduino / General Electronics / Re: BLE shield Arduino on: June 17, 2014, 05:36:39 pm
11  Using Arduino / Displays / Re: Looking for a bright 2.2" display on: June 16, 2014, 05:14:40 pm
An the last two sheets

12  Using Arduino / Displays / Re: Looking for a bright 2.2" display on: June 16, 2014, 05:13:38 pm
Yes, thats what I thought :-/.

I just found an 2.4" OLED color display with 320x240

The good thing is that Im already using 320x240, so I don't need to rescale my GUI smiley-grin.

Does anyone know if there is a sketch/driver for that?

13  Using Arduino / Displays / Looking for a bright 2.2" display on: June 15, 2014, 05:09:21 am

Im looking for a bright 2.2" color graphics Display. I was using the Adafruit 2.2" which is good but not readable in direct sunlight.

I was already looking for an OLED but it looks like they're not available in 2.2", at least not in this particular rectangle shape.

It would be a dream if it would have a resolution of 240x320...
Are there any available?
14  International / Deutsch / Re: Array einer funktion zurückgeben on: June 11, 2014, 06:50:10 am
Danke Ralf und jurs, so werde ich es wohl machen.

Habe gerade anscheinend noch Probleme mit meiner Syntax, könnte das eventuell jemand korrigieren?

int *getTime() {
 uint8_t myDate[6] = {0, 0, 0, 0, 0, 0}; //seconds,minutes,hours,date,month,year (last 2 digits)

  // send request to receive data starting at register 0
  Wire.beginTransmission(0x68); // 0x68 is DS3231 device address
  Wire.write(0);                // start at register 0
  Wire.requestFrom(0x68, 7);    // request 7 bytes (seconds, minutes, hours, day, date, month, year)
  while (Wire.available())
    for (int i = 0; i <= 6; i++) {
      if (i == 3) {
        int throwAway = bcdToDec(; //we dont care about the dayOfWeek
      else {
       myDate[i] = (bcdToDec(;
  return (myDate[]);

Ich bekomme noch folgenden Fehler
MUO_2_2inch.ino: In function 'int* getTime()':
MUO_2_2inch:254: error: expected primary-expression before ']' token

15  International / Deutsch / Re: Array einer funktion zurückgeben on: June 11, 2014, 03:03:09 am
Aber die funktion DateGenerator() generiert mir ja das Array das es vorher nicht gibt. Zwar kann ich es im loop definieren jedoch kann die funktion dann nicht darauf zugreifen und schreiben, oder sehen ich das falsch?

Mein Ziel ist es ja das von DateGenerator() generierte Array an die Funktion displayTime() zu übergeben....

Soweit ich also verstanden habe geht es nicht. Schade, also muss ich alle meine Arrays global definieren, ich dachte ich könnte meinen Code etwas übersichtlicher gestalten und so die unnötigen Array definitionen weglassen.

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