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1  Development / Other Software Development / Re: MultiSpeed I2C Scanner - 50,100,200,400 KHz. on: February 10, 2014, 01:01:39 am
I have added a link to your MultiSpeed I2C Scanner in http://playground.arduino.cc/Main/I2cScanner
See the "Interesting Links" section.
But I don't like that link to reply 4.

robtillaart, could you give your Multispeed I2C Scanner it's own place and adjust that link in the i2c_scanner ?
You could add it to the i2c_scanner page, but perhaps that is confusing for new users, that page is very simple now, and that is better for new users.
Another option to edit your first post, and make that the main article and for your scanner.
2  Using Arduino / Audio / Re: Why the Sparkfun Si4735 radio shield is all wrong on: November 21, 2013, 05:42:03 pm
I can't find it on Ebay.
It is okay if you post a (commercial) link to your Ebay item, after puttting so many work in it.
3  Using Arduino / Motors, Mechanics, and Power / Re: Using 12V for Piezo buzzer issue on: September 13, 2013, 06:59:44 am
...driven anti-phase...

http://playground.arduino.cc/Code/ToneAC
4  Using Arduino / Networking, Protocols, and Devices / Re: How to connect two MPU6050? on: September 03, 2013, 01:17:42 pm
Are you sure the INT is open collector and can be tied together ?
The 'dmp' sketch sets a default for the sample rate to be placed in the fifo. That is not ment for two devices, so perhaps you can't do all the calculations in the example. Don't add a delay in the sketch.

This all I can think of at the moment.
5  Development / Other Software Development / Re: yet another DHT11 Class for Arduino on: July 18, 2013, 10:21:16 pm
The same goes for the DHT lib, http://playground.arduino.cc/Main/DHTLib
The datasheet of the DHT22 tells: "...then MCU will pulls up and wait 20-40us for RHT03's response". The only way to wait for a response is to let the pull-up resistor make the signal high, and not by making the output high with the Arduino pin.
6  Development / Other Software Development / Re: yet another DHT11 Class for Arduino on: July 11, 2013, 05:19:55 pm
The point is: In my code I let the Arduino never output 5V. The high level of the signal is only done by the resistors. This also prevents a shortcut when the Arduino outputs 5V and the sensor tries to pull it to ground.
7  Using Arduino / Sensors / Re: Using GY-521 Accelerometer + Gyro on: July 10, 2013, 01:02:42 pm
I used the datasheet(s) as a framework to set up a basic sketch.
The idea is that if the code has been proven to be okay (it is), someone might use it to extend it and put it in a class.

So all the defines are the registers and the bits in the registers. I named them the same as in the datasheet(s).
You have to keep the datasheet next to it, to know what it is about.

But that is not all, there are also undocumented registers.
If you take a look at the code by Jeff Rowberg, you see he has more registers.
http://www.i2cdevlib.com/
https://github.com/jrowberg/i2cdevlib/blob/master/Arduino/MPU6050/MPU6050.h
8  Development / Other Software Development / Re: yet another DHT11 Class for Arduino on: June 12, 2013, 08:47:53 am
Rob Tillaart,

I don't know if I open an old issue, but I'm not convinced that the Arduino should set the line high. I read the datasheet over and over again, and I think it is not very clear but I read the datasheet as if the resistor pulls the line high.

The datasheet tells that the "DHT pulls up voltage...", but I assume it is an open collector output. So they mean the pull-up resistor. So when the datasheet tells that the "MCU pulls up voltage...", I think they mean it in the same way.


Your code:

Code:
        pinMode(pin, OUTPUT);
        digitalWrite(pin, LOW);
        delay(18);
        digitalWrite(pin, HIGH);
        delayMicroseconds(40);
        pinMode(pin, INPUT);

But this works as well:

Code:
        // The line should be set as INPUT_PULLUP.
        // Make it output to pull it down.
        // Wait at least 18ms, so let's wait 25ms
        pinMode(pin, OUTPUT);
        digitalWrite(pin, LOW);
        delay(25);
        pinMode(pin, INPUT_PULLUP);
        // The DHT11 will react in 20 - 40us.
        // Let's wait 50 to be sure it has responded.
        delayMicroseconds(50);

I use the resistor to make the pullup. So there will be no shortcut when the DHT11 pulls the line down.
I also wait 25ms, since 18ms is the minimum.
And I wait 50us, to be sure that the DHT11 has already pulled the line down.
9  Using Arduino / Audio / Re: Why the Sparkfun Si4735 radio shield is all wrong on: June 08, 2013, 03:25:36 am
Surface solder points and surface scratchable/breakable traces are okay for me.

What about solder points for a single row header for an add-on board ?
The same way a shield is connected to an Arduino board.

The default Arduino 100kHz I2C bus is good enough. You are not going to stream audio via the I2C. Selecting a radio station is only done once, and reading RSSI a few times a second is all that is needed.

Are you going to use that tuned-antenna circuit (with the 18pF and 180nH) ? I hope not. I would like 100pF to the FM input with protection diodes, and perhaps an inductor 1u ... 4u7 as a filter for the SW.

I see many designs without a capacitor on the FM antenna, but I break too many FM modules by accidently touching the antenna with a DC voltage.
10  Using Arduino / Audio / Re: Why the Sparkfun Si4735 radio shield is all wrong on: June 07, 2013, 07:09:50 pm
I would like to tune to LW, AM, FM, SW from the Arduino.
So I want to be able to switch the antenna for FM and SW, and also switch between a AM ferrite and LW ferrite antenna. At least I want to be able to add that myself.
11  Using Arduino / Audio / Re: Why the Sparkfun Si4735 radio shield is all wrong on: May 17, 2013, 03:28:47 am
Did you read the document about the antenna circuit.
The 180nH and the 18pF are for a 'tuned' antenna circuit.
It could increase the sensitivity, but if there is a mismatch, the reception gets worse.

I would like to see protection diodes for the antenna input.

Why is the green led on the SCK pin ?
You have so many unused pins, you might as well use another.

I think that sometimes a diode is used at the reset circuit. Parallel to R1. See the schematic of the Arduino Uno.
12  Using Arduino / Sensors / Re: GY-521 gyroscope/accelerometer breakout board on: May 10, 2013, 06:33:17 pm
You can read the datasheet for the sensitivity.

Or use the i2cdevlib and read about the functions. You still have to read the datasheet to understand how much 'g' the acceleration value is.
http://www.i2cdevlib.com/

About the distance and position, I don't know. Sorry. I never tried to calculate that.
13  Using Arduino / Sensors / Re: MPU6050 SparkFun Breakout to Arduino Uno - No Communication on: May 03, 2013, 01:55:58 pm
That is the Sparkfun breakout board, https://www.sparkfun.com/products/11028

Connect it as written a few posts earlier.
Vcc and Vio to 3.3V
SDA and SCL are the I2C bus. The Sparkfun board has already 10k pull-up resistors.
Gnd to Gnd.

I don't know PIC microcontrollers. Do they have a I2C bus ?
14  Using Arduino / Audio / Re: Why the Sparkfun Si4735 radio shield is all wrong on: March 25, 2013, 06:36:12 pm
I don't know if I can make a good RF board.
If perhaps 5 people will use it, it is not worth it.

The breakout board (not the shield) of the SI4735 is good for making your own design.
The link in my first post is to someone who used the breakout board.

But the SI4735 still lacks SSB for the shortwave. And it can't receive the CB band (27Mc).

I bought a used radio with SSB and and was going to connect the buttons to an Arduino. But to do that I would have to take the radio completely apart and it still looked as if it was new. So I don't have an Arduino controlled radio at the moment.
15  Using Arduino / Sensors / Magnetometer HMC8553L undocumented registers on: March 09, 2013, 04:55:00 am
Hi,

I'm testing the HMC8553L magnetometer.

The documented registers are from 0 (0x00) to 12 (0x0C).
I found undocumented registers at 13 (0x0D) to 59 (0x3B).
Some are Read/Write or Read Only or Write Only.
Some are to change the sensitivity or to invert an axis.

Where can I find more information about this ?

Please don't try to write to those registers, some undocumented registers make the sensor unusable.

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