Pages: [1]   Go Down
Author Topic: 4x4x4 Cube (muxing with TLC5940 or TLC5951  (Read 844 times)
0 Members and 1 Guest are viewing this topic.
Offline Offline
Newbie
*
Karma: 0
Posts: 4
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hello, everyone. I'm building an 8x8x8 cube and have eight TLC5951s and a handful of a P-channel Power MOSFET found at http://www.ti.com/product/csd25401q3. I'm pretty new to embedded electronics, and - specifically - transistors, so I was wondering how I could use the driver and transistor in combination to be able to mux one horizontal plane at a time. All of the RGB LEDs in one horizontal plane share an anode. My µC runs off of 3.3V and defaults to an internal pull-up. Thanks!
Logged

Global Moderator
Boston area, metrowest
Online Online
Brattain Member
*****
Karma: 514
Posts: 26252
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

http://www.ti.com/lit/ds/symlink/tlc5951.pdf

Each TLC device will control a row of LEDs. Eight devices will control 8 rows, that's 1 layer. All the anodes from 1 layer will have current sourced from 1 PNP, or P-channel, device.
All the LEDs in a column get their cathodes connected in parallel, to a single TLC pin.
Send out TLC data for 1 layer, enable that layer's current source.
Repeat the next layer.
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Offline Offline
Newbie
*
Karma: 0
Posts: 4
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

http://www.ti.com/lit/ds/symlink/tlc5951.pdf

Each TLC device will control a row of LEDs. Eight devices will control 8 rows, that's 1 layer. All the anodes from 1 layer will have current sourced from 1 PNP, or P-channel, device.
All the LEDs in a column get their cathodes connected in parallel, to a single TLC pin.
Send out TLC data for 1 layer, enable that layer's current source.
Repeat the next layer.

Thanks. Having the drain connected to 3.3V, source to the TLC5951 pin, and switching the gate between GND and 3.3V has no effect (LED is always on).
Logged

Global Moderator
Boston area, metrowest
Online Online
Brattain Member
*****
Karma: 514
Posts: 26252
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Source goes to the RGB LED anodes. LED cathodes go to the TLC pins.
What you are doing is selecting which set of LEDs are having current sunk thru them by the TLC.
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Offline Offline
Newbie
*
Karma: 0
Posts: 4
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Source goes to the RGB LED anodes. LED cathodes go to the TLC pins.
What you are doing is selecting which set of LEDs are having current sunk thru them by the TLC.

Sorry... that's what I meant. What you described is my configuration. Switching the gate between GND and 3.3V does not change the state of a test LED. Any tips?
Logged

Global Moderator
Boston area, metrowest
Online Online
Brattain Member
*****
Karma: 514
Posts: 26252
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

You are sure its a common anode LED?
LEDs might also have higher Vf, need more than 3.3V to turn on.
Got a part number?
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Offline Offline
Newbie
*
Karma: 0
Posts: 4
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hm... I doubt that's the issue; like I said, it's always on.
Logged

Global Moderator
Boston area, metrowest
Online Online
Brattain Member
*****
Karma: 514
Posts: 26252
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

VGS = –2.5V 13.5 mΩ
VGS = –4.5V 8.8 mΩ

At 3.3V it should switch on/off okay.

Can you post a pic of your setup?
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Pages: [1]   Go Up
Jump to: