connecting Multiplexer to 7-segments LED question

Borna

Hello all,
I’m working on a project with stamp II and need to display a 4 digits number to 4X7-segments LED. I have purchased MC14489BP multiplexer. Can someone please help me explain if I want to display a 4 digit number s such as 1234 which pins on the MC14489 need to be connected to which pin on the 4 X 7-segments LED? I'm very new to these stuffs and not sure about which pines get connected to which pins
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You can see the technical data for MCI14489 at this link
http://www.jameco.com/wcsstore/Jameco/Products/ProdDS/241824MOT.pdf
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The LED data can be found at this link
http://www.futurlec.com/LED/7SEG4RCC.shtml
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Thanks for the help

Jon Williams

I'm a bit swamped right now, so the best I can do is share some code for you -- the MCP14489 is a little tricky and doens't lend itself to a quick explanation.· But, if you look over the product docs and my program, you'll probably figure it out without much trouble.

BTW, my November column in Nuts & Volts magazine covers the MC14489 and does go into detail.· It should hit newstands shortly.

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Jon Williams
Applications Engineer, Parallax

Borna

Hello Jon, thanks for the replay.
from what I underestand looks like MAX7219 is an easier to use than MCP14489

do you know if there is any difference between MAX7219 and MAX7219CNG? can both be used to drive 7-sigments LEDs?
Thanks
Borna

Jon Williams

I don't know that there's any difference -- you should be able to download the spec sheet (hint, hint...) and suss it out from there.

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Jon Williams
Applications Engineer, Parallax

Borna

Hi Jon
You said you're covering the MC14489 in more details in Nov issue of nuts and volts. Can I get this magazine from bookstore such as borders book store or Barnes·& Noble? Also is there anyway to have access to the schematic of coin counter article?
Thanks
Borna

Jon Williams

Yes, you can usually find·Nuts & Volts magazine in larger book sellers like Barnes & Noble, and in the magazine section at Fry's Electronics.· I just got the November issue in the mail yesterday, so it should be in stores now.

I've attached the MC14489 portion of the coin program -- the "coin" inputs are just active-low push-buttons.

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Jon Williams
Applications Engineer, Parallax

Borna

Thanks again for your help. I will try to buid the circuit tonight.

Jon Williams

Note that the schematic I provided is for the PDB -- you don't nee the 470 ohm resistors if you're using another board (they're part of the PDB and can't be removed).

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Jon Williams
Applications Engineer, Parallax

Suzi

Hi Guys,
I'm new to basic stamp and loving it so far. Jon, I looked at your code and have a few questions and wonder if you can help me

What is the purpose of the following

config = %11101101 ' setup for "HELLO"

also do you always call Update_Cfg after a call to Update_Segs?

oh I forgot what is the purpose of Decode characters such as
Ltr_H CON $2
why do you give it a value of $2
thanks
Suzi

Jon Williams

Suzi,

The reason for those bits of code is that I'm doing what is required by the MC14489. Download the data sheet for that part and study it carefully, the code will start to make sense. The other thing you can do is pick up the November issue of Nuts & Volts magazine; my column discusses the MC14489.

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Jon Williams
Applications Engineer, Parallax