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Topic: ulm2803 connections (Read 1 time) previous topic - next topic

aes92000

595, ulm2803 and uno for 8x8x8 rgb cube

i built cube with 3904's and turned out to be a $#^@* job.  the 2803's seem to be an esier setup and a lot smaller board.

by googling, i am understanding i do not need the resistors ahead of array like the 3904's, is this correct??

is my schematic looking correct for wiring

PaulRB

#1
Dec 03, 2014, 07:32 am Last Edit: Dec 03, 2014, 08:06 am by PaulRB
Hi, you don't need resistors between the 595 outputs and the 2803 inputs, if that's what you're asking. There are 2K7 built-in to the 2803 inputs.

I think the pin labelled CD+ (normally labelled COM) on the 2803 should go to 5V rather than ground.

A simpler design than this would be to use tpic6c595. This is a medium current shift register similar to the 74hc595 but with fet transistors on the outputs, so the 2803 would not be needed.

If only someone had already designed a board combining an Arduino and a bunch of tpic chips and would be willing to sell you one....

Paul

larryd

Connecting pin 10 to ground will turn on all the LEDs, similar to a lamp test.
Pin 10 is connected to + on the o/p power supply for relay coil snubbing.

You are using LEDs so pin 10 can be left open.
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aes92000

thanks for replies and hope everyone is having good holiday(s).

where i have my account to purchase supplies, it's either a crap-load of 3904's (200+) or 2803's (25)
i like the idea of the 2803's simply for easier wiring and smaller board IF the design will work the same way.

if understanding correctly,
i can omit the wiring to pin10 completely
i DO NOT need the resistor between 595 being the 2803 have the 2.7k already


larryd

i can omit the wiring to pin10 completely
Yes if you are driving LEDs

i DO NOT need the resistor between 595 being the 2803 have the 2.7k already
Yes
No technical PMs.
If you are asked a question, please respond with an answer.
If you are asked for more information, please supply it.
If you need clarification, ask for help.

aes92000

THANK YOU ;D

im excited now to get started.

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