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1  Using Arduino / Installation & Troubleshooting / Re: [SOLVED] Arduino Uno R3, Mac OS 10.9.1 Mavericks, Device is not detected on: February 16, 2014, 04:06:44 pm
I have the same issue with all my UNO's, it suddenly appeared. Leonardo is fine. Uploading using an Atmel AVRISP MKII also works well. My UNO's are having 0.001 firmware!!!

Very recent Macbook Pro Retina (latest revision).

My Arduino version: 1.0.5 with Teensyduino 1.18 installed.

I solved it by using the beta 1.5.5 software, uploading Pro Mini Firmware, then reuploading the UNO firmware. Now the UNO's are just fine again. Strange problem. I also have students with strange UNO problems.

This even solved it for the 1.05 version (Teensyduino is not yet working with 1.5.5. afaik)
2  Using Arduino / General Electronics / Re: Digital Potmeter: shifting resistor interval on: January 19, 2014, 04:31:50 pm
I agree. I think the only solution is to make one myself, using e.g. an 8-output digital switch and a resistor array. Will give a reasonable result I think. As I understand, that is actually how digital potmeters work inside.
3  Using Arduino / General Electronics / Re: Digital Potmeter: shifting resistor interval on: January 19, 2014, 03:00:10 pm
well, I'm just doing my best trying to explain it... if I was more affluent at it I didn't need to ask did I? I always try myself first. The application works, we only want to improve it.
4  Using Arduino / General Electronics / Re: Digital Potmeter: shifting resistor interval on: January 19, 2014, 02:54:46 pm
Well it is, but we did several setups, so the latter is complimentary. About the previous answer, I am aware of that, but that is as it is. We only want to influence the in-between resistor.
5  Using Arduino / General Electronics / Re: Digital Potmeter: shifting resistor interval on: January 19, 2014, 02:31:06 pm
Well we tested it with a variable resistor (actually 1K normal potmeter, 100k resistors were 10k in out first setup) in parallel but also replaced it with a variable resistor. Both options worked. But... we want to control it, and that is why we need a small controllable variable potmeter, but they are hard to find. Doesn't matter if we get a more complex circuit from that.
6  Using Arduino / General Electronics / Re: Digital Potmeter: shifting resistor interval on: January 19, 2014, 02:01:32 pm
well, my current circuit is like this, it is an experimental project to see how things work, (I help some students that are doing the project):
                         a1                  a0
5V ---[ 100k ] -|- [ x ohm ] -|- [ 100k] --- GND

at a0 and a1 we read the voltage. We want to vary the resistor of x ohm, that normally is 10 Ω fixed. But, the problem is that if we connect a 10k potmeter between a1 and a0 it is just way too course (because it has 256 steps).
7  Using Arduino / General Electronics / Digital Potmeter: shifting resistor interval on: January 19, 2014, 12:20:30 pm
I have an (educational) project that has a small resistor that I need to influence. The original resistance is about 10Ω.
I want to influence it using something like a digital potmeter. But they seem to be mostly available in versions with much higher  resistance.

Any good ideas on how we should approach this? We already tried several components (including a normal potmeter), but we want to have a good resolution so we hope to approach the 10Ω level (probably 100Ω would be very fine as well).
8  Development / Other Hardware Development / Re: Teensy 3.1 on: December 21, 2013, 05:35:41 am
Paul did a great job... Again!!! I received the Teensy 3.1. within a week (US -> NL).
9  Topics / Home Automation and Networked Objects / Re: Issue with reading reed sensors / NFC PN352 on: December 01, 2013, 03:59:45 pm
I have ordered some CD4043 latches. Will cost me an extra pin (to reset the thing), but wel at least remember the state of my sensor I hope!
10  Topics / Home Automation and Networked Objects / Issue with reading reed sensors / NFC PN352 on: December 01, 2013, 02:29:01 pm
I have a small project involving an NFC/RFID Shield (Seeedstudio), an Arduino UNO and two reed sensors. I want to do some action af there the first reed sensor is activated, then scan the RFID tag and then check the second reed sensor. The reed sensors are connected with a pull-down resistor for each of them and like one would normally do to deal with the floating inputs issue.

For some reason the PN532 is blocking the other sensors (on digitlInputs). I see the second sensor but that seems to be because I just read the RFID, the other way around is troublesome (I need to wait quite long and then the first reed sensor is detected)...

If I uncomment nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A) then the reed sensors work very well.

I should be able to use interrupt 0 for the Seeedstudio NFC shield (http://www.seeedstudio.com/depot/nfc-shield-v20-p-1370.html?cPath=19_24) but after soldering the pad and using the attachInterrupt on one, it does not trigger the event. At the adafruit site I have seen this info: http://forums.adafruit.com/viewtopic.php?f=31&t=40185 but my NFC shield is using SPI, not TWI / I2C.

I was thinking that I could probably use a work around that sets some register to high, and will leave it high till I write a low to it or something like that, because I think the problem is that the Arduino is too busy to detect the HIGH event because the hardware works well.

Update:
I'm actually thinking of using a SR-latch so that I will be able to detect a high, then reset the latch and wait for another detection.
11  Development / Other Hardware Development / Re: Troubles with FTDI on a custom Arduino on: September 25, 2013, 11:58:51 pm
It should definitely have been wired to ground indeed! Must have been a momentarily blackout I'm afraid, or inherited from an earlier bad moment smiley
12  Development / Other Hardware Development / Troubles with FTDI on a custom Arduino on: September 22, 2013, 12:38:44 pm
I am having trouble getting an external FTDI like usb2serial light working with this custom Arduino project:

http://ministickers.nl/Media/schematics.png

As you can see, I included a capacitor of .1uF / 100nF 50V. What do I miss that is in the original Arduino's?
Of course I can and do use my ISP programmer, but especially for my students the FTDI board is more convenient.
13  Topics / Product Design / Re: Interesting behavior, what would be the problem? on: August 05, 2013, 04:07:43 pm
Yups, one of the only options indeed, I will try to! Thanks!!!
14  Topics / Product Design / Re: Interesting behavior, what would be the problem? on: August 05, 2013, 08:19:12 am
Well it does (have the cap between the uC Reset and DTR), I abbreviated Reset to RST (but might cause confusion because there is also an RTS of course in a serial port application).
15  Topics / Product Design / Re: Interesting behavior, what would be the problem? on: August 05, 2013, 05:43:24 am
I thought so (I looked at the datasheet of the pro mini), and soldered a 104 / .1uF capacitor between RST and DTR, but it doesn't seem to work like that either! I use the official Arduino Ethernet FTDI module to test it.
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