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1  Using Arduino / Programming Questions / Re: Why the L ? in 86400L for instance ( days from Unixtime ) on: Today at 02:01:57 am
Thanks guys,

I want to actually study this stuff when I get caught up, but I have been working 14 - 18 hours a day since Christmas ( which is why I havn't been on the forum for a while ) but soon I hope, I can study it a bit and fill in all these many missing gaps of knlowledge .
2  Using Arduino / Programming Questions / Why the L ? in 86400L for instance ( days from Unixtime ) on: September 21, 2014, 10:45:47 pm
I must have missed this somewhere, and I have tried searching the forum.

I am building a display that is updated every day at midnight, using a simple RTC for timing ( it has to run for weeks )

To test it without waiting for a whole day  each time, I thought I could change the / 86400 for getting days from Unixseconds to say 864, and make it advance 100 times a day .

I dont know why there is the L after the divisor, so can I just use  ?      
Code:
int rxday = now.unixtime() / 864L;


Well I tried that and it is working, refreshing every 14.4 minutes, so perhaps the L forces it to a long integer ??
3  Using Arduino / Networking, Protocols, and Devices / Re: 433Mhz Modul with Virtual Wire | NRF24l01+ with Mirf/NRF24 didn't working on: September 21, 2014, 03:54:30 am
I use the simple Hope 433 Mhz tx and rx modules, and I connect the +5 of the transmitter to the PTT pin of the 328 ( to save even more battery power ) and the data to the nominated  data pin.

You have to set which pin is which in setup, and the baudrate of the VW link has to be the same each end of course.

Also you cant use pin 9 or 10 for pwm if you are running VirtualWire.
4  Community / Bar Sport / Re: How many times is someone not replying after asking question ? on: August 27, 2014, 02:39:46 am

one definition of ASKHOLE :-

Someone who wastes other people's time by posting questions on discussion forums when the answer is only a Google search away - or answered many times previously.
5  Community / Bar Sport / Re: searching for a robotic (arm) project? have a look at this! on: July 18, 2014, 04:03:26 pm
Quick enough for fencing Bob ?   :-)
6  Using Arduino / LEDs and Multiplexing / Double the output, ( or viewing angle ) , same current , half work for a MAX7219 on: June 20, 2014, 10:50:12 am
I have tried a search on this subject, but quite honestly the forum is so big now, that it takes ages to sift through the threads bought up.  This might be old hash .

Let me just run this past you guys....

I made a soccer scoreboard with 7x5 displays last year , Using the SAA1064 chip , which gave a 50% duty cycle , for max output from each LED.
I am now making some more boards using the MAX7219 driver.

I have arranged it this time with 5 columns across and 7 high .

This means I can set up in the register to limit to 5 columns, and skip the other 3, giving more brightness ,  20 % duty cycle, but still down on the 50% duty cycle of last years

The LEDs I am using this year are more than twice the output of last years ones, so I should be back on track with the actual  apparent brightness of last years project.

Now I have a request for a similar sign twice the digit size  ( 4 times the area ) but I have realised that I can put 2 red LEDS in series in place of the previous one ( each has 1v9 voltage drop ) and the chip should be able to supply Imax to both LEDs in series at 3v9

So in theory I can get twice the light output per column, using twice the number of LEDs, with the chip now running cooler, as it doesn't have to get rid of the extra ( 5 - 1.9 v )

But since  now I am saving the power dissipation in the chip, perhaps I can pulse the LEDs with twice the current as before ?  Giving me twice the light output for the same digit ?  ( OK at double the supply current, but there is no such thing as a free meal ! )

How does this sound ?

If you are not upsizing, you could tilt every other LED by half the viewing angle and get the same intensity as with one LED.





7  Using Arduino / Project Guidance / Re: bytes and nibbles on: June 16, 2014, 11:27:38 am
Too true.
8  Using Arduino / Project Guidance / Re: bytes and nibbles on: June 16, 2014, 10:13:48 am
Ans some tired old guys in the middle of the night still get them transposed  ,,,,   :-)
9  Using Arduino / Project Guidance / Re: bytes and nibbles on: June 16, 2014, 09:51:33 am
This thread shows absolutely the advantage of the Arduino community, I made a stupid mistake that my Great Grandson would not have typed , and instead of wasting a whole day finding it, you guys picked it up.

I am not interested in trying raspberries or whatever, I have had so much support ( even though I am still stuck in V22 until I can find a few hours to upgrade  my libraries to V1.05 )  and its working for me, who didn't have a clue about micros 3 years ago ( at 63 )
10  Using Arduino / Project Guidance / Re: bytes and nibbles on: June 16, 2014, 08:45:01 am
Not quite , more like  "  Ah, So "  :-)

11  Using Arduino / Project Guidance / Re: bytes and nibbles on: June 16, 2014, 07:50:15 am
Yes thanks, I had just spotted it and called myself a name that my wife often hears :-)

Thanks Guys
12  Using Arduino / Project Guidance / bytes and nibbles on: June 16, 2014, 07:22:57 am
I am busy just trying to put together some building blocks for my next sketch, and I keep tripping over this confusion on my part.  The top code works fine to display a 7x5 matrix character :-
   
Code:
   byte displayArrayA[5] = {63,63,136,72,72};
  lc.setRow(0,0,displayArrayA[0]);
 lc.setRow(0,1,displayArrayA[1]);
  lc.setRow(0,2,displayArrayA[2]);
 lc.setRow(0,3,displayArrayA[3]);
 lc.setRow(0,4,displayArrayA[4]);
 
So I thought I would tidy it up by having a variable for the 0 -4 in each line :-

 
Code:
for (x=o; x<=4; x++ ) { 
  lc.setRow(0,x,displayArrayA[x]);
  }

But it tells me I am trying to convert an integer  to a byte or a byte to a byte, or whatever, I have tried all the religions when declaring the x , but am getting confused again.
I have searched and somebody had a similar hassle but it was to do with pointers that I havnt come across yet.

Feel free to tell me I am missing the obvious again.
13  Using Arduino / Project Guidance / Re: 7 changes to 0 on only 1 BCD switch SOLVED on: June 08, 2014, 03:17:02 am
sometime during debugging another hassle, I commented out line 2 here

 Serial.println("TX setup");              // for debug only
  // vw_set_rx_pin(0);
  vw_set_tx_pin(9);    //  Tx module connections and speed
  vw_set_ptt_pin(13); // powers Tx and LED
  vw_setup(2000);

I must have added that at some previous time when I had a problem, but uncommenting solved it.

default pin for rx even if you are only using a transmittter is 11,  and I am using that to scan F,   so I guess the VW makes it an input.

Thanks for your time guys.
14  Using Arduino / Project Guidance / Re: losing eeprom value on: June 07, 2014, 08:51:36 pm
It wouldnt be an issue  in my application anyway, the data will probably only be changed once a month anyway, but I need to read the data after a power failure ( quite a lot here in Africa :-)

15  Using Arduino / Project Guidance / Re: losing eeprom value SOLVED on: June 07, 2014, 06:25:46 pm
Thanks for the replies guys,  you got it there Roger, when I removed the int from in setup, all is well.

I just want to get caught up with my 22 projects, and then read a bit more about all this stuff, ( and even update to V1  :-)  ) but at the moment its just juggling balls in the air, but it is great to have you guys for advice.

And I did just think about reading the eeprom for the display, but can't remember why I didnt, -  oh yes,  I was going to check if reading an eeprom had a life limit, but I dont think so ...
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