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1  Using Arduino / Sensors / Re: problems using BMP085 & HMC5883L with Adafruit Datalogger on: August 13, 2013, 12:57:27 pm
sorry to necro an old thread but I try to always post solutions when I have them.

After getting a replacement datalogger shield (same model and supplier as before), and testing it with a 2nd sensor board (again, same model as before), they worked without apparent problems.

Testing the old sensor board without the datalogger gave the same problems as before. So it looks like the 2 items are compatible without modification, I just fried the sensor board.
2  Using Arduino / Sensors / Re: problems using BMP085 & HMC5883L with Adafruit Datalogger on: August 03, 2013, 08:16:55 am
I ran the scanner on another sensor board of the same model without the data logger and got this:

I2C Scanner
I2C device found at address 0x1E  !
I2C device found at address 0x53  !
I2C device found at address 0x69  !
I2C device found at address 0x77  !

It might be a few days before I can give any more updates as I've just destroyed the data logger with some bad soldering, which kind of illustrates why I don't want to attempt removing any of the resistors on the sensor board. I notice Adafruit have an LSM303 board, so I might just get that instead.
3  Using Arduino / Sensors / Re: problems using BMP085 & HMC5883L with Adafruit Datalogger on: August 03, 2013, 04:15:34 am
This photo shows all the I2C sensors in the project, including the barometer, thermometer, magnetometer, accellerometer and gyroscope. The only sensor connected but not shown is the DHT-11 which is wired in parallel with the ground and 5v lines and uses it's own non-I2C data line to pin A0.
4  Using Arduino / Sensors / Re: problems using BMP085 & HMC5883L with Adafruit Datalogger on: August 03, 2013, 02:45:00 am
Thanks for the reply, that looks like the shield I'm using.

I ran that I2C sketch and got this:

I2C Scanner
I2C device found at address 0x68  !

The I2C sensors are all integrated into a single breakout board. I'm still learning to use these components so unfortunately I don't actually know much about how it works internally, including the value of the pullup resistors, I don't think the seller does either. I think the board includes it's own level shifter, going by the claim "IIC communication protocol (fully compatible with 3-5V systems)".

The arduino board I'm using is a Duemilanove.
5  Using Arduino / Sensors / problems using BMP085 & HMC5883L with Adafruit Datalogger on: August 02, 2013, 11:12:44 am
Hi, I've been working with an Adafruit Datalogger shield for a while and I've just built a sensor array for it, but the sensors don't seem to be working. So far there's a MultiWii board (a BMP085 barometer and HMC5883L 3-axis compass, along with an accelerometer and gyroscope that I haven't tested yet, all on the same board, sharing the same I2C connectors). Near this is a DHT-11 that is wired in parallel with the MultiWii's ground and Vcc lines. The connections are as follows:

GND - MultiWii Ground, DHT11 Ground
5V   - MultiWii Vcc, DHT11 Vcc
A0   - DHT11 Data
A4   - MultiWii SDA
A5   - MultiWii SCL

Here's the problem, when I try the example sketch for the HMC5883L, it seems to work but constantly gives the same bearing, except for every few seconds when it spits out 1 line of a totally different bearing then goes back. It doesn't change in response to movement or the presence of nearby magnets, apart from the 1 line fluctuations the heading is always the same.
The BMP085 example sketch just says that there is no valid BMP085 found and to check the wiring.
The DHT11 seems to work normally.

I've had the MultiWii sensor board working fine before, I'm wondering if I've damaged it with either the soldering iron or ESD, or if it's somehow incompatible with the datalogger. Testing the datalogger on it's own before adding the sensors it seemed to work fine, both the SD card and the RTC module. Has anyone else used these parts together? any ideas or advice?
6  Using Arduino / LEDs and Multiplexing / Re: Using BC517 transistor to drive 300mA LED array on: May 29, 2013, 01:20:10 pm
Thanks everyone for the fast response. I take it then if I add a 1k resistor between the arduino and each base pin, a 1k resistor from each base pin to ground, and an appropriate resistor (selected by an LED resistor calculator) between each diode bank and it's corresponding collector pin, those resistors should control the current that passes through the LEDs and transistors? or is something else needed for current limiting?

Most of the resistors I have are 1/4 watt, I take it higher wattage resistors would be needed for the LEDs, but would 1/4 watt be sufficient for connecting to the base pins?

PS: Be aware the BC517 darlington has >1Volt collector-emitter saturation voltage - that means for you the fully saturated (on, fulll 300mA current) its power dissipation will be >0.3Watt.

Would that cause overheating problems? because the board is likely to be packaged in quite a tight space. I have some less powerfull LEDs that I might use. Anyway, thanks again.
7  Using Arduino / LEDs and Multiplexing / Using BC517 transistor to drive 300mA LED array on: May 28, 2013, 02:31:53 pm
This is a bit of a noobish problem but I've about half finished my first proper arduino based gadget and I want to make sure I don't burn anything out. I'm trying to drive an array of LEDs from an ATMEGA328P, 1 bank of white lights that can be used as a flashlight or emergency beacon, and 1 bank of IR transmitters for using the IRremote library. (It's a bit of a multitool).

The problem is I'm not sure how best to drive them, as each LED draws 100mA, making 300mA per bank. I was planning on using a BC517 transistor on each pin, as shown here:

This circuit seems incomplete, and I don't know if the BC517 is fast enough for IR communication. It seems like there would need to be a pull-down resistor between each base pin and ground, is that needed? What about a series resistor between the arduino pin and the base pin? Any help or advice would be much appreciated, I've been reading bits and pieces of theory but it just feels like I need to get a foothold on this.
8  Using Arduino / Storage / Re: Can't get any SD card to initialize on: March 19, 2013, 03:10:16 am
The back of the board only has the maker's name and website, LC Studio. I'll try reformatting the card.

Please DON'T connect arduino 3.3V to this module's 3.3V. That pin is probably an output from the onboard 3.3V regulator.

Too late, but thanks for the warning. I tried it with just the 5v at first, when it didn't work I plugged in the 3.3v as well. The arduino hasn't shown any sign of damage but I'll keep the 3.3v disconnected now.

9  Using Arduino / Storage / Re: Can't get any SD card to initialize on: March 18, 2013, 02:28:22 am
hi, thanks for the reply, I can't find a model number for the card reader but it looks just like this one:
(I hope it's ok to post links to ebay here, if not apologies in advance). It's not a shield, the board is just a bit larger than the SD slot.
 I've got an LCD plugged in at the moment and noticed the CS pin on that is pin 10, so I'll try changing it to 10 on the card slot (I take it I can just edit the sketch and move the wire?)
10  Using Arduino / Storage / Can't get any SD card to initialize on: March 04, 2013, 08:11:19 am
Hi, I have a problem that I'm hoping someone here can solve. Simply put, I can't get any SD card interface to work at all. I've tried 3 different boards, 2 of them the blue ones that are all over ebay at the moment that take full size SD cards, and 1 is a micro-sd slot built into a 1.8" LCD. All 3 of them fail to initialize the card when I run any of the example SD sketches. I've tried with multiple SD cards, including an old 256mb, a micro-sd, a regular 2gb and an SDHC card. All have the same effect.
I've redone the wiring multiple times but I can't find any error in the connections, here is the current state (arduino on the left):


3V3   goes to +3.3
5V   goes to +5
Gnd   goes to GND


4   goes to CS
11   goes to MOSI
12   goes to MISO
13   goes to SCK
GND   goes to GND (there are 2 GND pins on the card board)

I've tried it with 2 sets of cables, with and without external power (9v from a transformer plug), I've checked that the card clicks into place, and still get the same error. I'm still learning to use the arduino so is there something simple I've missed? If it makes any difference I'm using a Duemilanove, female-female breadboard wires, and a block of right angled interface pins to make the I/O ports compatible with the wires. I can post a photo of the setup if it would help.

Thanks in advance for any advice or suggestions you can give.
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