Hi everyone,
as part of a bigger project I'm going to build a (hopefully) nifty little controll for a couple of seven segment displays (gonna call them 7SDs from now on) I had lying around from one of those cheap surprise packages.
It's supposed to give a nice interface for a microcontroller.
Now I thought I'd post it here hoping for some feedback of you guys. Maybe I forgot something or there are better ways of doing it. After all I am not very expierienced in the field of electronics yet.
And of course I hope this thread will help someone who's looking for something similar.
So, here's what I got so far.
The displays:
And this is the datasheet for it... or close enough I guess: http://www.es.co.th/esmobile/Schemetic/PDF/TOD-4201FG-B.PDF
And after some coffee and a bit of research I came up with this. It's hand-drawn for now but since I want to make a PCB I'll put it in KiCad soon. Of course I'll make those files available here.
The schematic is in the attachments.
A little bit of explanation on my schematic:
So, if you have some experiece: What do you think? Have I missed something or is there anything I could optimize?
And if you dont: I hope this thread helps you!
as part of a bigger project I'm going to build a (hopefully) nifty little controll for a couple of seven segment displays (gonna call them 7SDs from now on) I had lying around from one of those cheap surprise packages.
It's supposed to give a nice interface for a microcontroller.
Now I thought I'd post it here hoping for some feedback of you guys. Maybe I forgot something or there are better ways of doing it. After all I am not very expierienced in the field of electronics yet.
And of course I hope this thread will help someone who's looking for something similar.
So, here's what I got so far.
The displays:
And this is the datasheet for it... or close enough I guess: http://www.es.co.th/esmobile/Schemetic/PDF/TOD-4201FG-B.PDF
And after some coffee and a bit of research I came up with this. It's hand-drawn for now but since I want to make a PCB I'll put it in KiCad soon. Of course I'll make those files available here.
The schematic is in the attachments.
A little bit of explanation on my schematic:
- The 3 blocks marked "shift" are going to be 8-bit SIPO shift registers. I thought of making it 1 16-bit and 1 8-bit register but then I would have to use 2 instead of one clock-inputs and we wouldn't win anything. I got some of these lying around, so I'll use those: http://www.ti.com/lit/ds/symlink/cd74hc164.pdf
- The 4 blocks marked "7446" are going to be 7446-ICs like this one: http://www.ti.com/lit/ds/symlink/sn5447a.pdf
- Now, I have read that some 7446s already have resistors built into them so I might be able to save 14 of those R1 resistors.
- The resistors connected to the 7SD are going to be the R1 resistors, all the same value which I havent calculated yet.
- The unmarked resistors are the second type (R2) which I'm going to choose so that the transistors are saturated. (Hope I'll do this correctly.)
- The thing marked LTJ is either a jumper or I'll make it a push switch which is in on-state when not pushed. Anyway, it's going to be ment for the LampTest function of the 7446s.
- The transistors on the bottom are meant to drive the cathodes of the individual digits and the anodes of the dot-leds. If you don't get what I mean take a look at the datasheet for the 7SDs and look at the internal circuit diagramm on the bottom of the first page.
- The blank lines are logic-lines the red ones are simply +5V supply and the brown ones are common ground.
So, if you have some experiece: What do you think? Have I missed something or is there anything I could optimize?
And if you dont: I hope this thread helps you!
Attachments
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