I am having trouble with telosb Mote, because I don't know how much time it takes when a command to turn it off is executed. Can anybody help me out, please?
I think it's very fast. You can set it to be 192us. But note that if you have a lot of code before the turn off command, the telosb will do them before been turned off. Say if you have an infinite loop before the turn-off, your telosb will never be turned off.
So consider that I think you may be looking for the turnaround time rather than the turn it off command time. The turnaround time is the time the radio switch from the Receive to Transmit or from transmit to receive. The time is 12 symbol. You can refer to the CC2420 radio documents which used by the telosb motes. https://inst.eecs.berkeley.edu/~cs150/Documents/CC2420.pdf
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I have a real-time Clock module and I'm trying to make an RGB Clock out of it. There is a particular line of code that sets the time and date to the real-time clock module. I put this in the setup code but every time I reset the Arduino it runs that line of code again. Is there any way that I can make sure that once this line in of code is run it will never run again even if I reset the Arduino?
It is a broad question which goes beyond programming. The answer to your concrete problem is "Remove that line of code" from setup, it will not run (I am sure you know this). However, you should provide some physical input (buttons + rudimentary menu-like interface) to set the clock on first usage. A second way of setting the time can be a serial port to which you can physically connect. This requires some code to read that serial port in your loop method.
In the release version of you Clock firmware I would leave just reading the time stored in EEPROM (from RTC module or an external chip), not the hard-coded value in setup.
Your RTC might have a bit saying "RTC stopped", which you might use to switch to "normal behavior". It will be set when removing power and the RTC-battery. The RTC will probably read "1-Jan-1970 00:00" then, and won't increment unless set.
However, your demo code to set the RTC is just demo code, not intended to really use as is. (See Victor's response for more details)
I'm trying to make a tetris game in ocaml and i need to have a piece move through the graphics screen at a certain speed.
I think that the best way to do it is to make a recursive function that draws the piece at the top of the screen, waits half a second or so, clears that piece from the screen and redraws it 50 pixels lower. I just don't know how to make the programm wait. I think that you can do it using the Unix module but idk how..
Let's assume you want to take a fairly simple approach, i.e., an approach that works without multi-threading.
Presumably when your game is running it spends virtually all its time waiting for input from the user, i.e., waiting for the user to press a key. Most likely, in fact, you're using a blocking read to do this. Since the user can take any amount of time before typing anything (up to minutes or years), this is incompatible with keeping the graphical part of the game up to date.
A very simple solution then is to have a timeout on the read operation. Instead of waiting indefinitely for the user to press a key, you can wait at most (say) 10 milliseconds.
To do this, you can use the Unix.select function. The simplest way to do this is to switch over to using a Unix file descriptor for your input rather than an OCaml channel. If you can't figure out how to make this work, you might come back to StackOverflow with a more specific question.
I am working on a project that requires me to use 2 separate Arduinos running independently from each other. Now, both of these Arduino's are running the same code, but I noticed that after 10 minutes or so, one of them falls behind and this time difference keep increasing with time. Like I already mentioned, the Arduino`s are identical and I bought them at the same time and they are running the same copy of the program. Any ideas what might cause this and how can I fix it?
Thank you.
Here is the link to the Arduino that I bought just in case.
My Arduino modules on Amazon
The Crystal Oszillators have tolerances up to 100ppm (extreme case), which means you could possibly get 16Mhz*100ppm = 1600 clock pulses difference per second. Also the differences of the runtime could be caused by small voltage differences. Even if there is a voltage Regulator on the Board it has small tolerances, based on the fact, that it operates in the Range of MHz this can climb up to an recognizable Offset.
A possible solution is a synchronization of both microcontrollers. I'm not an expert, so the following solution is a possible and easy one, but definitly not the best.
If they are near by each other you can use two pins of each controller. One as Input and one as Output. Write something like this in your code (same for both if you use the same Pins):
digitalWrite(outPin, LOW);
while(digitalRead(inPin)){};
digitalWrite(outPin, HIGH);
Connect the Output from the first to the Input from the second and the same from second to first.
This results in a waiting state for each cycle of the faster Controller until the slower one reaches the same Programm Part. But be careful if one of them stucks somewhere it will stop the second one too. So there is no redundancy! if this was your goal, don't use this method and search for other synchronisation methods.
Perhaps you can use some RTC (real time clock) hardware to help you to keep they synchronised. They are really cheap and easy to use.
I'm building a small robot that uses a relay to power the motors. To run the relay, I have it connected to pins 11 and 12. If I use something like the Blink example, where it turns the pin on, then off a second later, it works fine. However, what I'm trying to do is keep a pin on until an IF statement is met. When I run it, it turns the pin on for a millisecond or so, then off permanently. How could I get this to work?
Well, I have a couple guesses, but your description is vague without knowing what the IF statement is...maybe it is being met somehow without your knowledge.
I am pretty certain the light is staying on longer than a millisecond in order for you to see it. As a side note, here is an interesting, related article: http://www.100fps.com/how_many_frames_can_humans_see.htm
Are you debouncing? http://arduino.cc/en/Tutorial/Debounce
I can imagine a simple program with an IF to count button presses -- or the timing of -- where, without debouncing, you will meet the conditional without it seeming correct.
This is just one possibility, but without knowing the code, or the setup it's hard to say.
I have a problem in getting clear and not jumping values from MPU9050 DMP. I used Jeff Rowberg's code. The problem is when I use the code all is perfect, YPR is very smooth. But when I use that in my program with delay I have jumping values over time. Depending on the delay, jumping values vary.
I used a delay because I'm reading the serial values by unity and unity needs a little delay on the Arduino side to read the data. Can someone please tell me what the problem is and how I can fix it?
Thanks a lot.
It is likely that the fifo buffer is overflowing, leading to incorrect data. This would happen if you put in a delay that lasted for longer than your dmp frequency is. One strategy you could use is to read the data as fast as you can from dmp, but only send data over the serial port every other or every three readings, depending on what kind of delay you need between readings.
If you edit your question with what your dmp frequency is and what your desired serial frequency is I could try to help more.