7 SEGMENT LED, LCD 2x16, and 25 LED's

Hi all,

My first time with Arduino, I am using the UNO and it is fantastic !
Already done some LED blink, and the usual first timer stuff, and I am well impressed with everything.

I initially looked into arduino for my hobby which is flight sim's.

I wanted a board that could handle I/O and any other tasks, and this seemed to fit the bill.

What I want to know is if I wanted to run a 2x16 lcd, 4x 7 segment leds, and a LED matrix of about 25 leds would it be possible to do on the UNO or would I need look into different shields ?

If I need different shields could someone suggest one that would be suitable ?

Thanks in advance.

I'd use some simple shift register to drive the matrix LEDs and possibly a dedicated 7Seg decoder chip for the each of the 4 7seg. These can usually cascade so you only need 4 data, latch and clock (6 pins). The shift register can cascade another 3 pin. The LCD probably already is suitably mounted on some board so it does not need a shield as such, but they tend to use 10(?) pins. In other words, not a standard shield - the layout is too special. Remember you can use the A0-A5 pins as digital output, too.

I think you can do all that with a MAX7221 in nodecode mode and an SPI interface LCD panel, such as

The '7221 can do 8 7-segments; wire up 4, and use the other 4 to drive 32 LEDs in place.

So you need 5 IO: SCK, MISO, MISO, chip select for LCD, chip select for MAX7221.

thank you for the reply's I will look into it now.

Really impressed with this open source Arduino, thanks 8)

Another query if I may,

For unknown reason I got 4 individual 7 segment led's I want to run them as pairs, am I better of buying duals ?

Or can I still use them ?

You can still use them, not too differently from duals.

Use them the same. Still connect alll the segments in parallel, still have single common anode or cathode for each digit.

Thanks for the reply's, its really helping while I am planning my build.

I have decided not to run the LED matrix,

So I will only be running one 16x2 lcd and four 7 segment led's as pairs.

Can anyone point my in the right direction, can I run this from the uno, or will I need to use other components.

Which LCD are you using? An SPI interface'd unit as suggested in reply #2, or something else>?
SPI display

only needs SS, MOSI, SCK connected (altho MISO is also tied up).
Another SS can be used to drive MAX7221, it will drive 4 digits and then up to 32 other LEDs (plus 4 decimal points from the 4 digits if not being used).
So 2 SS's, SCK, MISO, MOSI, 5 pins.
2 pins for serial interfacing with the Flight Sim.
Leaves you 13 pins free for buttons or whatever.

Thanks for the help, the lcd and Led's linked below is what I have

1602ZFC 16x2 Alphanumeric LCD Module
ebay link

and 7 segment led's
ebay link

Ooh, that's too bad.
That LCD needs 11 control lines.

Had to hunt around for a datasheet on the display
Green common anode part, so you need to fool around with PNP transistors or a UDN2981 type part for multiplexing too.
0.3" viewable at 3 meters (10 feet).

So, 11 for LCD, 7 for segments, 4 for digit selection, 2 for serial, and you still have those 25 other LEDs, need 3 or 4 more digit selection lines, so so yeah, you're gonna need some additional hardware, or a processor with more IO pins, like something 1284 based, with 32 IO.

Thanks for the reply CrossRoads,

I no longer need the other 25 LED's so it will just be the LCD and the segments.

and is it possible to purchase these other boards ready made or is it purely self construction ?

Most of the 16x2 LCD modules will also support using a 4 bit data bus instead of 8 bit so you could reduce the LCD pin count by 4.

I have now ordered a 4 bus lcd so that will save on some pins :slight_smile:

and no need for the LED matrix

so just need to cover the 4 7-segment led's

possible on the uno ? or still need to expand ?

Yes, I sell the bare boards for the '1284 I showed, almost all thru hole & intended to be easily assembled. $4.50 if you want one (maybe $5 for shipping to UK, would have to check on that), needs $12-15 in parts. The surface mount parts are the 2 regulators and the power fuse to protect the USB port, all big pads with wide spacing. The PL is here Cross Roads Electronics

With the other LCD selected:
So, 11 is now 7 for the LCD, 7 for segments, 4 for digit selection, 2 for serial, that uses All the IO on an Uno.
You don't have a need for any buttons or other IO?

You're going to need a small board to hold the LED displays, the 7 current limit resistors for the LED segments, a transistor array if you are multiplexing whole digits (vs multiplexing all 28 segments), you could add a shift register to drive the segments and gain a few pins back that way also. Or add two, and drive the digit transistors the same way, and gain those pins also. (common shift clock, data pin, and 2 unique output latch pins).

What I am doing is building the upfront controller from a AV-8B Harrier, I have already built a keypad and I am using another board to handle all of my key presses.

The main reason for using the UNO was to control the LCD and the segments, I will be exporting data from the sim I fly to display real time data on the lcd / led's on my upfront controller

with luck lol

I am still going through a huge learning curve at the moment, so thanks for the help you guys have given me.

and I will take a look at your site, and keep it in mind as I slowly build.