Blain, did you ever get the display working?
I'm asking because several more might become available in a few weeks.
If you post a blog on the website with a photo and the tech info, I'll
go to the trouble to pull all the displays I can. I'll save at least a
few for you (or whoever posts it on the website) and toss the rest in
the free box.
That is, if anyone gets it working and posts the info....
On 10/12/2014 11:40 PM, Paul Stoffregen wrote:
On 10/12/2014 11:13 PM, Blain C wrote:
Do you have any idea how they were wired up? Or is it gonna be a
total guessing game? Knowing the pinout of the connector would be
great, at least. :P
Here's the info I can share.
This display is 3:1 muxed, so you need to shift in 40 bits to control
all 5 'HC595 chips, and do that 3 times for the whole display, of
course repeatedly to keep refreshing it.
All the bits you shift in are active low. 0 turns a LED on, 1 turns
it off.
The first byte controls the LEDs farthest from the input. In each
byte, the low 7 bits control the 7 segments. The MSB of the first 2
bytes is ignored. On the last 3 bytes, the MSB controls which of the
places (ones, tens, hundreds) those 5 bytes control. As you refresh
the display, clear one of those 3 MSBs and set the other 2.
Just clock in 40 bits, then pulse the latch pin high to use them.
The enable pin needs to be low for the display to work. On the green
boards, it's got a pullup resistor. On the yellow prototype, the
pullup was mistakenly connected to data. The idea (with the pullup)
is for the display to default to off, rather than showing something
random. If you don't care about that, just connect the enable pin to
ground.
As long as you apply power and ground correctly, and apply valid logic
levels to the 4 inputs, there's pretty much nothing you can do to
damage it.
Knowing that it's 3.3v is helpful, 'cause I would have probably given
it five out of habit.
-Blain
"So you're Chekov, huh? Well, this here's McCoy. Find a Spock, we got
us an away team." ~Murphy MacManus
"MOM! I'm goin' into my headphones now! If I'm not back in one hour,
just wait longer!" ~ Cameron Bartolini
On Sun, Oct 12, 2014 at 11:07 PM, Paul Stoffregen <[email protected]
<mailto:[email protected]>> wrote:
Yup, those were my doing. I believe I still have several more
hiding in old boxes, which will probably hit the free parts box
someday.
There were actually 2 different designs for that PCB, one with 4
displays, the other with 5. Neither has a schematic. They have
very different wiring. As I recall, the 4-display one was meant
to run on 5 volts, and the 5-display one used 3.3V power.
On 10/12/2014 10:52 PM, Aaron Eiche wrote:
IIRC, These were Paul's. I'm pretty sure they're just 595s in
series. I have mine out in my car right now. I'd be interested
in working it out as well.
On Sun, Oct 12, 2014 at 10:38 PM, Blain C <[email protected]
<mailto:[email protected]>> wrote:
Hey there, dorks,
At one of the previous meetings, I picked up an array of
five seven-segment displays (each three-digit with decimal
dots between each digit, a separator colon between digits 1
and 2, and an indicator dot on the top between digits 2 and
3, part number LTC-4624JR) driven by five 74VHC595 shift
registers.
It looks like custom work, and I was wondering if the person
who built them would happen to have the circuit diagram for
me to look at. I'm considering building this into a project
instead of setting up my own, and I'd rather not fry it in a
hurry.
The board is plain, and definitely not group order. I'll
attach a picture of the module below.
Any help is good help, but I suppose I could probably suss
out the circuit myself if noone knows.
Thanks!
-Blain
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