Propeller Powered 6.5" 6-Digit 7-Segment Clock
Duane Degn
Posts: 10,588
Ever since seeing Sparkfun's 6.5" 7-segment displays, I've wanted to make a clock using them as the display.
I used six TPIC6B595 high power shift registers (one for each digit) to drive the displays.
I had originally planned to use four digits in my clock. Fortunately one of the displays I ordered arrived with the decimal point broken off. After emailing SparkFun a photo of the damaged display, they sent me a replacement and allowed me to keep the original damaged display as well. So I then had five digits. I thought a six digit display would be more useful than a five digit display so I purchased one more display from SparkFun.
I had been trying to figure out what I'd do to make the colons needed for separating the hours, minutes and seconds. I thought I might use a red LED to make the needed dots. The broken decimal point gave the idea of trying to use it above one of the attached decimal point to make a colon. It took a bt of work to solder wires to the broken decimal point, but I was able to get the decimal point to light up when power was connected to the display.
I carefully removed the decimal point from one other digit. I used this second decimal point to make another colon.
I plan to display output from my lab equipment with this display. None of my equipment use more than four digits after the decimal so by placing the decimal point deprived digits at the beginning and end of the display, I could still use decimal points when using the clock to display data.
I included a DS1307 RTC with the project so the time is preserved when I turn the display off.
I'm working on some code to use a Wii Nunchuck as an interface for setting the time and for starting and stopping countdowns. I plan to add a wireless interface. I'd also like to make it easier for the clock to be portable. I'll need a way of attaching the battery and Propeller controller board to the back of the clock.
The six digits are attached to corrugated plastic (it looks like plastic cardboard). I used nylon nuts and bolts to secure the digits. I made the frame from expanded PVC. I learned about expanded PVC from Gordon here on the forum. It (expanded PVC) is cool stuff, just as Gordon claimed. It cuts easily with a table saw.
I ordered a piece of transparent red acrylic from Tap's Plastic (I actually ordered two pieces, since two piece didn't cost much more than one piece). The frame and front are all held together with Gorilla Tape.
I noticed in my controlling program, I have the duty cycle of the LEDs set to 50%, so the display should be able to be brighter than shown in the video.
Sometime in the future, I might paint the PCB of all the digits the same color. There are three different colors of PCB in the display. I personally think this is rather annoying since the PCB will likely be seen when theses are used in their intended purpose. For now, it doesn't bother me enough to paint them.
I used six TPIC6B595 high power shift registers (one for each digit) to drive the displays.
I had originally planned to use four digits in my clock. Fortunately one of the displays I ordered arrived with the decimal point broken off. After emailing SparkFun a photo of the damaged display, they sent me a replacement and allowed me to keep the original damaged display as well. So I then had five digits. I thought a six digit display would be more useful than a five digit display so I purchased one more display from SparkFun.
I had been trying to figure out what I'd do to make the colons needed for separating the hours, minutes and seconds. I thought I might use a red LED to make the needed dots. The broken decimal point gave the idea of trying to use it above one of the attached decimal point to make a colon. It took a bt of work to solder wires to the broken decimal point, but I was able to get the decimal point to light up when power was connected to the display.
I carefully removed the decimal point from one other digit. I used this second decimal point to make another colon.
I plan to display output from my lab equipment with this display. None of my equipment use more than four digits after the decimal so by placing the decimal point deprived digits at the beginning and end of the display, I could still use decimal points when using the clock to display data.
I included a DS1307 RTC with the project so the time is preserved when I turn the display off.
I'm working on some code to use a Wii Nunchuck as an interface for setting the time and for starting and stopping countdowns. I plan to add a wireless interface. I'd also like to make it easier for the clock to be portable. I'll need a way of attaching the battery and Propeller controller board to the back of the clock.
The six digits are attached to corrugated plastic (it looks like plastic cardboard). I used nylon nuts and bolts to secure the digits. I made the frame from expanded PVC. I learned about expanded PVC from Gordon here on the forum. It (expanded PVC) is cool stuff, just as Gordon claimed. It cuts easily with a table saw.
I ordered a piece of transparent red acrylic from Tap's Plastic (I actually ordered two pieces, since two piece didn't cost much more than one piece). The frame and front are all held together with Gorilla Tape.
I noticed in my controlling program, I have the duty cycle of the LEDs set to 50%, so the display should be able to be brighter than shown in the video.
Sometime in the future, I might paint the PCB of all the digits the same color. There are three different colors of PCB in the display. I personally think this is rather annoying since the PCB will likely be seen when theses are used in their intended purpose. For now, it doesn't bother me enough to paint them.
92 x 92 - 5K
Comments
This next picture is the board with all the shift registers on it.
And this last one, is the controller board with a Propeller, switching voltage regulators and DS1307 (far left with red electrical tape on it).
This code has remnants of all sorts of other projects. A LED array, sprinkler controller, radio control interface.
I'll post new versions as they become available.
I hope to add a wireless interface soon.
I believe the only part the code that works right now is the clock. The clock may be set using a Wii Nunckuck using he Prop's I2C lines.
I have had this display used as count down timer as well. I'm not sure if the count down timer works since I added the clock function.
Edit(3/11/15): Warning, the code attached is an old version. There are likely better options available.
I plan to upload this program or an improved version to my GitHub account
If there isn't code similar to what is attached here on my on GitHub, send me a message and I'll make and check for any improved versions of the code.
There are couple of things that make it easier for me to find time.
1) Good employees to do the tedious stuff.
2) Propeller assisted data logging and testing equipment that makes running the tests I perform go much faster (as well as more accurate, and more fun).
I should add, that I've been trying to make a point of finishing up some older projects that I've been working on for a long time. I also plan to document here on the forum some of my past projects. It will probably look like I'm more productive than I am as I post details about projects that have been the the works for a long time.
Cool project. For making the colons another option may be to use the large 10mm LED's or even the monster 20mm LED's. At one point they used to sell the 20mm ones at Radio Shack but I don't know if they carry them any more. You can still get them from Digikey.
Do you have an estimate as to when you can get more details about this project up?
Thanks.
I was just thinking about this project. I want to add a wireless capability to it so I might need to use a different Propeller board since this small one is running out of space.
Is there some aspect of the project you'd like me to cover first? Are you more interested in the wiring and hardware? Or do you want to see the software for controlling the shift registers so they end up outputing the time? (The code is really messy but I'll post it if you want me to.)
@Robert, Thanks for the kind words. Do you think I should use 10mm LEDs? I kind of like the colons the way they are but then it might be because I'm used to them this way. Do they look funny? (Do these light emitting diodes make me look fat?)
The code and the schematics specifically. messy code is fine by me.
They look fine the way they are. Just wanted to mention them since it may be easier to use a set of four 5MM, 10MM, or 20MM LED's instead of modifying the displays. That way you can leave the DP intact on each panel. It will help if you ever decide to reuse the displays for a different project that may need the DP.
Robert
That's what I thought you meant. I just started to second guess myself. Thanks for the ideas.
Messy code as been uploaded. I was new to the Propeller when I wrote a lot of it.
I think the shematic could be inferred from the pin outs. The shift registers in this project only sink current, they can't source current like many 595s can.
The board that's attached to the back of the display has nine wires attached to it. Six of the wires are the shift register control lines input, shift clock and register clock. One set for three shift registers. The other three wires are 5V, 12V and ground. The 12V go to each LED anode and each LED cathode connects with a pin of the high power shift registers.
I don't see any resistors on the board so I assume (and hope) the displays take care of their own current limiting needs. Again, I made this very earlier in my Propeller education, I hope I didn't make some big mistake in the wiring.
I'll try to work on a schematic some today.
I'll likely add some sort of current limiting resistor on the back of the board that has the six shift registers (if there aren't already some there).