Show Posts
Pages: 1 ... 53 54 [55] 56 57 ... 97
811  Using Arduino / LEDs and Multiplexing / Shiftout too fast for my ribbon cable. on: September 26, 2012, 10:24:42 am
I have a current project that uses 15 shift registers ( TPIC6B565 ) to light 7seg LED displays.

I am using Shiftout, which I have had good results from on many previous projects.

This particular project ( the project from hell ) has 3 banks of 5 displays ( 5 shiftregisters per bank ) with ribbon cable disychaining the 3 panels together.

There is 2.5 m  of ribbon cable all told for the 3 banks, and it looks like the capacitance of the ribbon cable is causing erratic displays when everything is connected.

Most of the 6 units ( 36 banks in all )  are fine, so I am obviously working on the edge of reliable communication here .

I scoped the data and clock lines at the far end of the daisy chain, and they are a bit rounded.

I can simulate the same type of errors by using my test unit that has resistors in each data line ( to save micros when testing the freshly soldered pcbs with occaisional shorts )

I could probably solve it by taking the last displays "out" data connection back to the receiver/decoder module, but this would need a new cable, doubled over at the receiver end.  Luckily I made the serial data pins the end ones of the ribbon cable, so I could snip that on the return side.

The problems of "them" plugging it in the wrong way round, plus the expense and time for making 12 new cables, lets me think it would be easier to just slow down the shiftout pulses.

I found an answer on       http://arduino.cc/forum/index.php/topic,39341.0.html     where BenF solved a members similar problem by recommending changing the Shiftout function.
It looks easy , but where do I find it ?  its all in the main part now, not a library.

Or is there an easier way nowadays ?
812  Using Arduino / Project Guidance / Re: Detect RF from cell phone on: September 26, 2012, 09:22:25 am
" I'm in the northern hemisphere, so perhaps things are different here, like with toilet swirl direction?  smiley-grin "

I think you are on to something there, we get the leftover toilet grade celphones down here :-)

I was involved with scrolling advertising machines in University cafeterias for some years , and the original method of sensing the end off each poster had a coil near the edge of the poster, and some metalic tape on the back of the poster where it should stop. ( it looked really horrendous )

Whenever they complained about the poster stopping half way, the tech would go out after hours and all was fine, so I went there during the day , and all the students were messaging on their phones at the tables around the scrollers !

I changed it to an optical system and it was fine.
813  Community / Bar Sport / Re: red and black wires can go anywhere right ? on: September 26, 2012, 09:13:43 am
So after I replaced all 35 burnt out LED drivers, and the micro, I took it all back to the factory yesterday, but ran out of time to connect it up myself, so I said I will come back this morning.

 I told the same guy ( who got the red and black wires revered )not to plug anything in till I have checked it.

They would lay all 36 displays out on tables in the factory, for this morning.

There was me worried about humidity and corrosion in Central Africa, but lo and behold I get in there this morning, and 4 of the displays are soaked in pidgeon crap !   all over the new chips, and the LEDs.

So I bring back the effected boards and washed them off with meths, and will spray them with clear laquer when they are really dry ( and tested )

They have always had a pidgeon problem in the factory, but didnt think about it.

They have now hung sheets of bubblewrap above the displays while testing -  hindsight !

This has turned into the job from hell, but at least I did spot a little bug in the software that I am busy with now.  The next order is going to be massive, so I have to bite the bullet for now ....  :-(
814  Using Arduino / Project Guidance / Re: Detect RF from cell phone on: September 25, 2012, 03:47:16 pm
In my experience, almost anything with a speaker or earphone will detect a cellphone operating nearby :-)
815  Community / Bar Sport / Re: Clocks using DS3231 or similar? on: September 24, 2012, 03:05:29 pm
We dont have a broadcast time signal here in South Africa, so I just use a cheap GPS module with inbuilt antenna for about $17  Fastrax UP501.

You dont need any buttons to set the time, and its always right time ...........
816  Using Arduino / Networking, Protocols, and Devices / Re: arduino IDE serial not sending carriage return still ?? on: September 24, 2012, 05:53:37 am
I just tested the SM20 range, at 9600 baud, and the transmitter on the front of my car ( bonnet/hood :-) ) and my son walking down the tree-lined road with the receiver ( with a flashing light ), so the height was about a meter off the ground.

Both antennas were actually too long ( I forgot to trim them ) at 185mm ,  and the reliable range was 500m , which is fine for my needs.

I will however set up the SSI ( now that I can command the modules ) and trim the antennas for max signal,  and try it again, just out of interest.
817  Community / Bar Sport / Re: Five Arduino users in all of USA? on: September 23, 2012, 03:27:04 am
Fair dinkum blue.
818  Community / Bar Sport / Re: Five Arduino users in all of USA? on: September 22, 2012, 05:17:16 pm
Quote
"Still no Australian flag though, people might get the wrong idea and think I'm a Pom*

Thats because you post in English Rob, try your next post in Australian, and see if the flag changes :-)
819  Using Arduino / Networking, Protocols, and Devices / Re: arduino IDE serial not sending carriage return still ?? SORTED on: September 22, 2012, 05:06:39 pm
OK, I did it with v22 by using below.  I copied bits from other posts, and this works.

I am really impressed with the SIM20 transceiver - especially now that I have hooked them up with Bill Porters EasyTransfer library -  what a pleasure.
By setting the AT commands below, the modules current drops to 30 microaamps after 2 seconds of no data in ( I am only using this feature on the remote control end because of battery life )

They reckon over half a kilometer range, so I am going to hook up batteries onto my 2 arduino boards, and go and see for myself .
Code:
 digitalWrite(AC2DPin, LOW); //command mode
   delay(120);
 SIM.println("AT+SRDEPS=1");
  SIM.print("\n");
 digitalWrite(AC2DPin, HIGH); // data mode
820  Community / Bar Sport / Re: Oddball Items, for Giggles on: September 21, 2012, 12:46:55 am
Quote
Just bought a Samsung 60" 240Hz refresh LCD TV.

60"  !!!    The eyes are finally going then Crossroads ?   Thats bigger than my lounge :-)
821  Community / Bar Sport / Re: Five Arduino users in all of USA? on: September 21, 2012, 12:42:23 am
I just added myself, I zoomed in on my house and clicked "add yourself"  and low and behold it put me downtown Cape Town near the popular drinking holes of the Waterfront  -  perhaps its an omen and I will be able to retire soon ?
822  Community / Bar Sport / Re: red and black wires can go anywhere right ? on: September 20, 2012, 06:42:31 pm
IC sockets are handy, but dont like being soaked in conformal coating, its Hobsons choice like having a Molex plug. These units are for tropical Africa and I dont want them corroding......
823  Community / Bar Sport / Re: red and black wires can go anywhere right ? on: September 20, 2012, 02:36:12 am
We could have met half way in Singapore ?
824  Community / Bar Sport / Re: red and black wires can go anywhere right ? on: September 19, 2012, 08:46:09 pm
Well the 35 replacement chips should arrive tomorrow, so I spent a couple of hours on every electronic guys favourite job,
desoldering 700 legs to remove the dead chips,
Sore eyes,   sore thumb ( from arthritus and a solder pump ) ,  I do hope the guy doesnt reverse the supply again,  GRRRR   :-(
825  Community / Bar Sport / Re: Extremes of ridiculous packaging on: September 18, 2012, 09:23:28 pm
I bought $150 ( I think it was ) worth of chips from Mouser to qualify for worldwide free shipping,  but I still had to pay about $30 handling fee this end ( South Africa ) to get that same size box as your photo.
Pages: 1 ... 53 54 [55] 56 57 ... 97