Brads Electronic Projects Forum

rd1196 wrote:in the schematic the 7442 ground is in the 12th pin but in the pic you showed us the its on the 8th pin are they both right or is the schematic wrong.

You will find that each IC may have the ground and VCC pins in different places.

Ground for the 7442 is pin 8 while VCC is pin 16

Ground for the microcontroller is pin 5 while VDD is pin 14

Just on a side note, we call the +ve connection on the 7442 VCC because it is made up of BJT transistors internally (the C is for the collector terminal) We call the +ve connection on the microcontroller VDD because it is made up of MOSFETS (the D is for the drain terminal)

And by the way, the schematic looks good to me!

really it looks good the vcc and ground from the decoder and microcontroller are good i dont have to add anything

Thanks Brad

Looking at your schematics, I think your 8x8 matrix lines from the 7442 are incorrect. and you need to had a GND to pin 12 of the 7442, this is a data line or control line and may give you the wrong results from the 7442 if this is left floating.

Hi Brad! I'm making the smiley face on my breadboard, i don't know how to connect the matrix, i have 12 pins on the matrix, can you explain how to make it with 12 pins.. a simple draw?? thank you!
marC:)

bitfogav has an excellent answer for this question. just check out the following link to another forum topic.

viewtopic.php?f=2&t=250

I am guessing that you mean there are 12 pins on each side of your matrix (which makes 24 total) This is made up of 8 common anode connections, then 8 common cathode for red and 8 common cathode for green. (8 + 8 + 8 = 24)

brad wrote:Can you upload a photo?

Hey Brad!

I have uploaded the video on my youtube of brad smile, tell me if it is okay, because i tried the scrolling digits and it doesnt seems to work ok!

tell me what you think!

here's the video : http://www.youtube.com/watch?v=5_yaGuvU ... e=youtu.be

have a good day
marC:)

Hi marC, looks to me like your matrix is wired incorrectly. can you please also confirm that your matrix has 24 pins ?


Gavin.

I agree with bitfogav, it certainly is cycling through the graphic data, but it must be wired incorrectly for it to be giving you that on the display. Have you had a read through this forum topic to see just how to connect the display? - do you need to rotate the display 180 degrees maybe?

i got these matrix from sure electronics, same as yours brad " http://www.sureelectronics.net/goods.php?id=230

i'm getting all mixed up.. i need a detailed draw of the connection.. along the brad smile schematic

here's how i wired up all this :

thanks!
marC:)

I can' really understand your schematic.

Are you able to maybe post a photo of your actual project? is it on a breadboard?

Hi Brad! Thanks for helping me out! I'm really have big trouble make this matrix works.. i will explain :

i just want to know the pin 1 of the 7442 goes to the word's name side and the first green wire from the left?? and the pin 2 of the 7442 goes to the pin 1 from the left of the other's side of the word's name? i don't know to to wire this schematic?

thanks!
marC:)

Hopefully this will help?

bitfogav wrote:Hopefully this will help?

matrixconnections.jpg

oh thanks big! that clear all up!


i will post a video soon

thanks again!
marC:)

Hopefully that helps, if you want to make the matrix display in RED leds then you need to swap the GREEN connections to the RED connections, if you need help with that then just ask and I will change the picture above for you.

Let us know if your matrix now works correctly




Thanks Gavin.