OpenSegment makes it easy to add a large 7-segment display to your project. Because larger 7-segment displays pull more power than a microcontroller is able to drive directly, the OpenSegment has 8 PNP and 4 NPN transistors in order to drive the segments at their maximum brightness!
The on-board ATmega328 receives data over multiple digital interfaces (such as TWI, UART and SPI) and does all the PWM and upkeep of the display so your main controller doesn’t have to. There are even two built-in functions that can be activated with solder jumpers. The counter function simply counts up or down, incrementing when you pull down SDO and decrementing when you pull down SDI. The meter function gives you a voltage read-out of the ADC!
OpenSegment runs at 5V and uses a standard FTDI connection for programming. The board is pre-flashed with a bootloader compatible with the Arduino Pro Mini @ 8MHz setting under the Arduino IDE. This firmware is an updated version of the Serial 7-Segment firmware designed to run on both devices. The commands will be largely the same except, of course, that this display only has decimals and no colon. See the datasheet for the Serial 7-Segment below to get an idea of the serial command set.
This skill defines how difficult the soldering is on a particular product. It might be a couple simple solder joints, or require special reflow tools.
Skill Level: Noob - Some basic soldering is required, but it is limited to a just a few pins, basic through-hole soldering, and couple (if any) polarized components. A basic soldering iron is all you should need.
See all skill levels
If a board needs code or communicates somehow, you're going to need to know how to program or interface with it. The programming skill is all about communication and code.
Skill Level: Rookie - You will need a better fundamental understand of what code is, and how it works. You will be using beginner-level software and development tools like Arduino. You will be dealing directly with code, but numerous examples and libraries are available. Sensors or shields will communicate with serial or TTL.
See all skill levels
If it requires power, you need to know how much, what all the pins do, and how to hook it up. You may need to reference datasheets, schematics, and know the ins and outs of electronics.
Skill Level: Noob - You don't need to reference a datasheet, but you will need to know basic power requirements.
See all skill levels
Based on 3 ratings:
I purchased this display to make a clock. I have it connected to a Raspberry Pi A+ using SPI. It works great. I’m using Derek Scholten’s Python library (see the link below).
I didn’t notice that the display did not have a colon for time. It’s not a deal breaker, but would have been nice to have.
Since the Pi can run two, I’m thinking of getting a second to display the date on my clock.
This is a relatively easy to use, affordable 4 digit display in a larger size. If you also have another Micro Controller in your project (e.g. an Arduino compatible), you can drive the display with very few I/O pins and have several protocols available. It has good library support and the only reason I didn’t give it a Five Star review is that this display lacks a colon, which is nice for showing the time.
I needed a precision speedometer for my tractor. I had to be able to read the display outdoors in full sunlight, and the display had to show my speed in 10ths of MPH.
This display was easy to configure and communicate with. I especially found the cursor control and decimal control a must for my project (my project only reads out three digits, so I masked off the first digit and then offset the display mounting in the bezel.)
I would suggest to those who want a colon (such as for a clock display) get creative and wire in a surface mount LED over one of the existing decimals. With a little work you may even be able to grind a little trough in the face and mount the LED flush, but I have not tried it myself.
One thing to note is that the blue display I bought lacked contrast and was very difficult to see in bright light conditions. This may be the case with the other colors as well, and the effect is even apparent in the product photos. The lack of contrast comes from the fact the segment bezels are cast in a white/diffuse plastic which, in bright lighting, does not contrast much with the light from the LEDS.
The visibility in bright lighting can be vastly improved with the proper color filter. I keep a swatchbook of sample gel cinematic lighting filters from Rosco in my desk for just such purposes. I found that placing the Roscolux #4290 CalColor Blue sample between my blue display and the clear protective window I made gave me a beautiful bright, deep blue over “black” appearance, which is easy to see even in full and direct sunlight with the brightness set at 75%.
It is interesting to note that even though the filter I used only transmits 15% of the light, the portion it sends through at about 400 nm is such a good match that the display ends up appearing much brighter.
Swatchboooks can be bought for a few dollars from places such as stagelightingstore.com and others. As I said, they are handy for all sorts of optics and lighting projects and even include several frosted and diffusion type samples.
I would guess that all of these Open Segment displays would benefit from the proper filtering.
All in all, I am very satisfied with this display and I cant wait to find an excuse to use one in a future project.
I wish I could copy/paste this information in the review sections for the other colored Open Segment displays, as I think it might be useful to others, but it does not look like I can post a review without actually buying the product. Maybe if one of the SF staff sees this they can copy it over to the others??