Seven Segment Display

[egkkman]

Hi Alan,

I hope this topic has not been covered before, I have checked so apologies if I have missed something.

In a previous post you say:

"In any event, any 7 segment led is really 8 leds - 7 segments plus the decimal point.
A Phidget LED64 would therefore be able to drive 8 numbers. (8 X 8 = 64)
Radios require 4 digits, possibly 5, Each MCP display requires 5 numbers, except heading and course which require 3. Therefore, each LED64 board would support, at most, only two functions.
One board for 2 COM displays, One board for 2 NAV displays, another for Transponder and ADF.
Starts to get expensive."

I plan to use Phidgets cards to set up my MCP displays. I have common anode displays. Each one has seven connections, one for each part of the number plus one for the common anode and one for the decimal point.

Am I right in thinking that one output is an anode connection and a cathode connection?

If so I have calculated the following:

I need 21 outputs for each course & heading readout so that's 63.

For the altitude I need 21 for the first three digits and only one for each of the last two digits. I have assumed as the last two digits only ever display zero that I can connect the six outputs that make up the zero together. So 23 outputs in total.

For vertical speed I have assumed 1 output for the first ‘minus’ digit, 7 for each of the next two digits and only one for each of the last two digits. I have assumed as the last two digits only ever display zero that I can connect the six outputs that make up the zero together. So 17 outputs.

For Speed I have assumed 6 outputs for the first digit (the ‘A’), and 7 each for two of the displays and 8 for the display that will display the decimal point when the mach speed is displayed as well as a number when IAS is displayed. So 28 in total.

So, an overall total of 131 outputs. Then there are various outputs required for the buttons on the MCP. So I reckon I should be able to use three cards for the MCP plus a few other functions.

Looking at your statement above I think I have messed up my calculations!

Would you mind checking my calculations and seeing if I have messed up.

I hope this all makes sense.

Thanks in advance.

Dave Miller

[CocnutAir]

Dave,
You mention the 'A' for speed. I take it this is B737 MCP.
The Phidget solution is not the best way to go for 7-segment displays.
Once one connects the segments to a Phidget card, how are the appropriate segments going to be illuminated to display each number?
A driver is needed for this. i.e. somebody has to write code to specifiy, for example, that to display the number "2", segments
"a", "b", "d", "e" and "g" need to be illuminated. That doesn't exist.
Phidgets had 7-segment cards once upon a time,
but abruptly discontinued the line after their offshore supplier botched the driver.
The "7"s were being displayed as "Z".
Other problem with Phidgets is that each of their encoders is a USB device.
I currently have this huge bundle of USB cables going into my MCP and EFIS panels, connected to a few USB hubs.
I am in the process of replacing my MCP-EFIS Phidget cards with my own custom cards. Will only have one USB cable driving MCP and 2 EFIS panels.
Another option I am looking at, is to develop plug-in cards for the phidget 0/0/16 that drives 7-segments and encoders.

List of 7 segment digit requirements is attached.

Regards,
Alan

[egkkman]

Hi Alan,

Thanks for your comprehensive and helpful reply.

Yes, B737 MCP, sorry about that.

The cards you have made to provide one USB input, is this something you are planning to market? If so I would be interested.

Otherwise it sounds like my best way forward will be Open Cockpit cards and SIOC then. I plan to use ProSim737 and from I can understand this combination works pretty well and is not too difficult to set up.

I already ahve two Phidgets cards which I guess I should use for LED indications on teh MIP & overhead.

Thanks very much for the table you provided.

I am new to all this but am willing to put in the work to learn.

Thanks again.

Dave

[mrmaster]

Hi, you should definitely take a Look at Arduino!!!! Together with the as1106 you can control 8 digit displays with 3 (!!) outputs (clk, cs, din) and a gnd and +5v

Connection is easily established via ethernet to your sioc server

Take a look at my website www.x737cockpit.wordpress.com for my sample code.

Marc

[bsv118]

Hi Alan
I have a 64LED wired with 7segment display on my 737 overhead; I have used them with FS9 PMDG 737 and Flyboys interface and they working well. Now I have just passed to iFly 737 and with FS2Phidget I light up all my cockpit; in FS2Phidget .ini file there is not any for Flight and Landing Alt displays. It's possible to make it? And if yes what I must doing?
Regards and many thanks
Stefano

[CocnutAir]

Stefano,

How did you wire 7-segment to phidget-64? Using 5 PNP transisitor method?
Are you currently evaluating fs2phidget 4?
Did I forget to add DigitalPressurization.ini ?
Email me and I will forward to you, or you can cut and paste settings below to an FsVariable ini file of your choice.

[FLT_ALT]
Offset=56AC
Length=2
FSType=Proportional
LoValue=-16383
HiValue=16383
Format=#######0
Multiplier=1
Divisor=1
Integer=False
NormalizeAngle=False
WriteOnly=False
[LAND_ALT]
Offset=56AA
Length=2
FSType=Proportional
LoValue=-16383
HiValue=16383
Format=#######0
Multiplier=10
Divisor=1
Integer=False
NormalizeAngle=False
WriteOnly=False
[FLT_ALT_KNOB]
LogicVar=False
Offset=56A9
Length=1
FSType=Digital
OffValue=1
OnValue=2
Format=#######0
Multiplier=1
Divisor=1
Integer=False
NormalizeAngle=False
WriteOnly=False

Regards,
Alan

[bsv118]

Hi Alan and thank you for answer
7 segment displays are wired directly (common anode to black wire and every pin to red wire); yes I use fs2phidget 4. I'll try your settings and mail tou for feedback.

Stefano

[CocnutAir]

How many digits in 7-segment and how many red and black wires did you use?
You did read this entire post, right?

[bsv118]

Hi Alan
excuse me for mistake: I have wired in this mode:
- common anode to red wire
- all pin (without the pin of the point) everyone to one black wire;
- 4 7segment (last 3 of flt alt and the last one of lnd alt) have pins connected in series like one single led.
every display (10 in total) have 7 segment wired with 7 black wire and the common anode wired with one red wire. I will use iFly 737. I need a mode to assign a function to any led of 7segment display (like do flyboys interface for fs9 pmdg 737.

[bas_v]

Hello egkkman,

You probably should also check here: http://www.pjrc.com/teensy/td_libs_LedControl.html

I'm biased since I'm using this hardware option with X-plane 9. The creator of the board has an excellent plugin supporting the Teensy board with X-plane.

I agree with Alan that using a generic IO card involves more work than what is strictly necessary since you have to translate digits to individual outputs. The link I gave you has examples with the LedControl library, which has that translation already.

When using MS FS, you might be better of with this: http://www.flightsimparts.eu/Simulat..._7Segment.html

HTH