SteveyG, You were absolutely right! Turning all the displays off by putting some delay right before updating information got rid of the ghosting problem. But I had to put somewhat a large amount of delay to get rid of it completely by implementing a "for loop" that does nothing. This affects my duty cyle which is a little decreased but I can fix the brigthness of the LEDs. Maybe there is a better way of doing that but now I know what the problem is. Also now I understand what that "blanking feature" was for the BCD to 7-segment decoder. I assume if you do not use that feature, you get ghosting as well? Anyways, I did not spend too much time on software thinking that the problem was a hardware issue. Now it works. Thanks a bunch!
Indeed... In my code I disable the latch of the 4543 decoder, send new data, select the correct digit and then re-enable the latch (16 instructions = about 16µsec with 4.096MHz clock between latch disable-enable instructions). CD
No lots of updates at the moment (but lots of sorrows with my company ...) Still working on the code for the VFD version of the LED clock, and the code for the 2.1" 9-digit blue 5x7 dotmatrix version. I just received (for free!) a working red 2.1" 19-digit 5x7 dotmatrix PCB panel (75cm wide) complete with 74HCT164 shift registers and TD62003 drivers which will help debugging the code without having to develop a complete PCB for the display first. Edit: Picture of the messageboard (remember, PCB is 75cm wide): A first version of the LED clock main PCB, complete with solder mask and silkscreen, will be sent out in a few days for professional manufacturing. Still looking for a solution for the manufacturing of the enormous 68x14cm display board for the 4.0" displays as my Circad'98 PCB demo version doesn't allow for Gerber export, and my Sprint Layout PCB software doesn't allow for boards bigger than 30x30cm... In the meanwhile I finally found white 4.0" LED 7-segment displays at LEDs-buy.nl, but they are quite expensive (22.00 Euro each=132 Euro for six = about GBP91 or us$170). CD
LED Clock v.3 Here's another one for the collection which I built yesterday with some 7 segment displays I got last year from ebay for £1.50. The displays are 1" tall, with two LEDs per segment. The buttons on the back are (left to right) Brightness, Alarm on/off, Alarm set, Hours, Minutes, Seconds. I included an alarm with this clock so that I can use it as a bedside clock. Hopefully I'll get time tommorow to bend some clear red acrylic into shape to make a stand for it. When the alarm is turned on, the decimal point next to the seconds is illuminated. Pressing the "Alarm set" button on the back allows the alarm time to be set/displayed... There's a piezo sounder on the PCB for producing the alarm tone/tune. Because this is a piezo sounder rather than a piezo buzzer, it can be used to make melodious noises that I'm hoping might be more pleasant to wake up to... I'll let you know in the morning
A schematic wouldn't be much use on it's own. I'm still finalising the the firmware as there's one or two minor bugs if the buttons are mashed randomly...
*looks for a simple/cheap/no programming needed schematics and makes a clock* maybe this is a nice project for me this summer
Another... I've just whipped up another clock for the collection. This one was just for fun and as an experiment with a different style to the norm. I also included 100ths of a second on this one too As you can see, this clock was built on stripboard since I found some while sorting out the rubbish in my room - this is the first time I've stripboarded something in about 8 years and now I remember why I started making PCBs instead! I feel sorry for all of you who cannot make PCBs - stripboards are awful to work with! Still need to make cases for both of these clocks when I find time.
Hey these look cool! I was also thinking about showing the 100ths of a second on my clock but then I thought it would make me feel like i am in a hurry all the time or something do not wanna get paranoid.. By the way for your switches are you using vectored interrupts or simply poll for the I/O pins to see if they are high/low in your code? PS: How come I cannot post pics here?? Seems like i am not allowed to attach anything
Regarding the pictures, you have to host them elsewhere and link to them here using the [img ] [/img ] tags. Switches are either change on portb or external interrupts allowing the weak pull-ups to be used, though it depends on the PIC, number of switches and availability of port pins as to which I use. Please add to the thread with the clock(s) you've made
Hey SteveyG, Yeah I read about the thing earlier but thought it was for people who wanted to host pics from a server specifically. I guess we have to do it that way anyways eh? At the moment I do not have a website that I can host pics. I should look into those generic picture hosting websites I guess. So far I have one working prototype with 0.56" blue led's. That was the one I wanted to post the pics for. As far as the design goes, I am still thinking about whether I should add alarm functionality or not. I should definitely add auto light adjustment though. The 2.3" one will be very bright - which i like - but a bit distractive for sleeping I think. As soon as I get a host for the pics I will post them here. In the meanwhile I will work a bit more on the code to make it more functional. By the way with daily work and coding with a new uC architecture, this clock design is going much slower than I thought. I have not even started the PCB yet and seems like it will be a long time before I can do that... Cheers!
i just found this: http://www.sparkfun.com/commerce/present.php?p=GPSClock-1 It's pretty cool because it's HUGE, but the coolest thing is that it's GPS controlled. BTW: SteveyG: i love the large text display you made! i want something like that. I want it to be controlled via network, though. (could be done via the printserver in my router (USB or paralell))
So suprised this thread is still going, I recall looking at it at least a year ago I am about to embark on making a large LED clock, I have some LED digits (4" red) that were salvaged out of some old sports scoreboards I got for cheap. They have got serially loaded low side drivers, so no multiplexing issues to contend with (http://www.trademe.co.nz/Browse/Listing.aspx?id=58201950) - anyway, will probarbly make it a wall hanging type thing. - Electrically not an issue, just mechanically I need to resolve it. What I really want to do is make one that has large 16 segment displays (4" or 2.3"). Has anyone that has been looking around LED manufacturers seen any? I have had a look at some, but not found any 14/16 segmenters that are large (Blue would be nice too, but cant have everything)
I would like to make a large 2 or 3 digit Outdoor lap counter somewhere between 18 inches and 24 inches tall. It has to be able manually controlled to count up/ down by single digits 000 to 999 and be able to manually enter any digit needed at any time example we are at lap 20 but we need to go back to lap 18. I could get away with a 2 digit counter but would like the 3 digit as we run a few races over a hundred laps. I would also like to make it work wirelessly at a distance of 300-500ft but would not rule out a wired option. Anyone up to the challenge or have any ideas how to make this? email me at dkollander@juno.com
CME8000 We've made some progress towards our own clock. We are basing it around a Maxim MAX6954 display driver and C-Max time code receiver CME8000. The basic code seems to work fine for driving the blue 14 and 7 segment LEDs. Free running time keeping is pretty poor despite our best efforts. We are not having a great deal of luck getting the receiver to pickup a good signal. It seems whenever it gets anywhere near our breadboard, the signal gets close to 0. Has anyone else using any receiver with breadboard had luck and specifically, has anyone been able to make the C-Max CME8000 work? Thanks, Stuart
My clock Well, it's been 4 months since I got hold of the displays, but I have finally got my clock to work! It took two attempts to get the PCBs to work, even then I missed a driver off, so I had to bodge it, It's brighter that that IRL, just the flash lit up the segments a bit I used a PICAXE-28X and a DS1307 RTC, then a load of logic crap so I didnt need so many outputs, I also hooked up a IR sensor and temp sensor, so you can control it all with a TV remote, stuff like brightness, 12/24h display, showing the date and temperature and stuff, I just need to make a case for it now, then finish off the programming, cos atm you can't set the time without a computer
Hi Stuart, How is your clock project going? Very busy (too busy ) at the moment (profesionnally), not much time left for private projects... I have best results with the bigger LDR's (more sensitive than the smaller ones) I also bought some small and sensitive but more expensive Silonex NSL06S53 LDR's from Farnell (ref. 3168347). They are working perfect and have a TO18 case. CD
