Hi,
I am about embark on m first Arduino project which will be a cable tester.
I need to pulse 13 outputs, for each output I will need to scan 14 inputs looing for the corrosponding connection. I would like to use a nice display like the TFT LCD Screen and was thinking of using the MEGA 2560...
Just want to make sure the Mega & LCD screen work together as well as having enough (13) inputs & outputs over?
Any pointers or advice would be apprciated.
Bob.
Last month I had to build a tester for ribbon cables. 50 wire, 40 wire, and 26 wire. Standard ribbon connectors and DB25 male and female for the 26 wire ribbon. I used LEDs and resistors. Ran off 12 volts.
I only need to check for continuity as ribbon connectors are pretty difficult to cross up.
Are doing only ribbon cables, or are you doing other types where pins my be crossed up or even shorted?
I would have use an Arduino and shift registers to get to the 50 connections I needed, if other than ribbon.
How long are your cables? Will resistance be a factor?
Paul
Hi Paul,
These are rather complex harness looms (not ribbon cables) with several connectors, pins at one end do actually goe to a mix of pins accross other connectors and every pin has different combinations. They are easy to screw up when we make them so a tester is needed.
Short lengths (under 500mm) so resistance should not be a problem.
I have made a working rotary switch box to test some of these but it would be nicer with Arduino and the LCD display.
Did you use Arduino?
Bob
dudester:
I need to pulse 13 outputs, for each output I will need to scan 14 inputs
Please give more details. A diagram would probably be very useful.
Your words imply 13 * 14 = 182 inputs ? ?
...R
Robin2:
Please give more details. A diagram would probably be very useful.Your words imply 13 * 14 = 182 inputs ? ?
...R
Sorry the 14 was a typo, should have been 13, its the same 13 lines.
To simplistically draw it you could say two connectors with 13 pins and straight through connections, I just need to check for cross-overs and shorts on the other end. Its actually more complex than that as there are more than 1 connector with multiple wire cross-overs but that can all be checked in software.
So 13 inputs and 13 outputs, just not really sure how many outputs the LCD display takes up.
I am not sure just how sophisticated you want to make this.
if you connect all your sense pins into the analog pins and scan for each test, you will see if any have any sort of response.
pulsing can create an EMF based on wire location that may or may not be present on final installation.
but sending a pulse on each of 13 consecutive pins and scanning all lines for any shorts or other connections seems pretty easy.
connecting to a display is also not hard.
the mega offers more external pins.
offers you knobs and switches to make it do other things. pulse duration, possible pwm and test other things.
writing the code to display what you want on the display... ?
Hi, most colour lcd screens use an spi interface, so only around 4 or 5 pins. Some may have parallel interface, so maybe 10 or 11 pins. Either way, with a Mega you should have more than enough. Can you give links to/examples of displays you have seen on offer that you like? We can advise on suitability.
Paul (PaulRB)
Shift registers might come in extraordinarily handy for you, and you wouldn't necessarily need a Mega.
PaulRB:
Can you give links to/examples of displays you have seen on offer that you like? We can advise on suitability.Paul (PaulRB)
This is the only one I have seen didnt know there were more...
http://www.arduino.cc/en/Main/GTFT
For an N-wire cable, get an MCU with at least 2·N available GPIO lines. Connect both ends of your cable to the 2·N lines.
Arduino Mega has 54 digital input/output pins
http://www.arduino.cc/en/Main/arduinoBoardMega
maximum cable suports 27*27.
That TFT will need max of 7 or 8 lines, fewer if you don't use all its features, e.g. the sd card. It does however need some particular outputs from the Mega, not just any ones, but that won't be a problem.
There are many more displays to choose from. Search eBay for "arduino lcd" but don't buy until we have checked it for you.
Oh wow, there are lots more!!!
OK, how about this one...?
Where can I get a tutorial on setting this up and sending commands to it?
syntaxterror:
Shift registers might come in extraordinarily handy for you, and you wouldn't necessarily need a Mega.
this add a huge layer of learning. a MEGA would be simple pin by pin
dudester:
Oh wow, there are lots more!!!OK, how about this one...?
Where can I get a tutorial on setting this up and sending commands to it?
http://www.ebay.com.au/itm/391140673252
same thing, but uses serial connection.
dudester:
Sorry the 14 was a typo, should have been 13, its the same 13 lines.
Would it work if you connect each end of all 13 wires to Arduino I/O pins - 26 in all. so you would need a Mega. Set all of the pins for one end as inputs and for the other end as outputs. Then set all except one of the outputs HIGH and check the status of all the inputs. And work through each of the outputs in turn.
...R
'1284P with 32 digital IO would be enough. Use Display with I2C (2 pins) or SPI (3/4 pins) interface. And still have 0/1 free for serial debug messages if needed.
Could use my Bobuino2 with it's RTC and SD card. Each IO pin broken out with +5/Gnd for max flexibility.
Available with or without onboard USB/Serial adapter and screw terminals.
http://www.crossroadsfencing.com/BobuinoRev17/
dudester:
Oh wow, there are lots more!!!OK, how about this one...?
Where can I get a tutorial on setting this up and sending commands to it?
That one is text only, no graphics or colour, but easier for a beginner to use. What do you want to display on it? The library for this is LiquidCrystal. The display will need 6 or 7 Arduino outputs (any you like), unless you get the slightly more expensive serial version, as suggested, in which case only 2 pins (but a particular 2 pins).
Robin2:
Would it work if you connect each end of all 13 wires to Arduino I/O pins - 26 in all. so you would need a Mega. Set all of the pins for one end as inputs and for the other end as outputs. Then set all except one of the outputs HIGH and check the status of all the inputs. And work through each of the outputs in turn.
Yep, thats my plan.
But wanted to be able to have nice text messages for incorrect wiring such as "Pin 3 O/C" or "Pin 4 S/C to Pin 8" so the addition of an LCD was really my question but looks like thats no problem.
Thanks.
dave-in-nj:
this add a huge layer of learning. a MEGA would be simple pin by pin
dave-in-nj:
this add a huge layer of learning. a MEGA would be simple pin by pin
Thanks for the tip but to be honest, this is kind of an excuse to learn Arduino...
