Multiplexing Project
I have a basic stamp 2p40 (the 40 pin version)
I have 10 7 segment displays all (common anode).
I would like to learn how to multiplex the digits to display 0-9.
I need help understanding the following.
1. How do I turn on and turn off each display? Should I use an external Chip or clock? If so How do I do it?
2. How do I ensure the displays will be bright enough?
A. I know about using transistors.
B. What size resistor should I use for these displays to ensure proper brightness?
I have 10 7 segment displays all (common anode).
I would like to learn how to multiplex the digits to display 0-9.
I need help understanding the following.
1. How do I turn on and turn off each display? Should I use an external Chip or clock? If so How do I do it?
2. How do I ensure the displays will be bright enough?
A. I know about using transistors.
B. What size resistor should I use for these displays to ensure proper brightness?
Comments
http://www.parallax.com/Portals/0/Downloads/docs/books/sw/Web-SW-v2.1.pdf
Look at Experiment Number 31 which goes into the use of the Motorola MC14489 for multiplexing the seven segment displays. Although this only does 5 digits, with two of the units you would should be able to control all 10.
I think the MC14489 is the why to go as MSDTech suggested. Go take a look at the Data sheet for the MC14489 "mouser.com",Plug the part# in the search window then click on Data sheet when the page opens. Since this is a 5 digit decoder and Your loading it w/ 10 digits in ,5 digits will over flow. the "data out" pin on the first MC14489 should be tied to the "data in" pin on the 2nd MC14489. This will make use of all 10 digits sent out. I forgot to look at the BANK out pins , But this will be in the datasheet
Hope this helps, If not drop another post reply and will go from their.
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Chris Savage
Parallax Engineering