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#1
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Digital I/O Expansion
I have to expand i/o on a system that now has only 4 inputs and 4 outputs.
I need 12 inputs and 13 outputs. Anybody got any ideas, i thought this would be easier. Im familiar with the '249 output latches '151 and input multiplexors but cant seem to get what i need... ????? |
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#2
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Digital I/O Expansion
Hard to offer any advice when you give no clue as to the type of system you
are talking about Computer Data Logger Controller of some type etc -- Dan Hollands 1120 S Creek Dr Webster NY 14580 585-872-2606 www.QuickScoreRace.com "David Andrews" wrote in message news:tpS7f.9607$%A1.9383@trndny01... I have to expand i/o on a system that now has only 4 inputs and 4 outputs. I need 12 inputs and 13 outputs. Anybody got any ideas, i thought this would be easier. Im familiar with the '249 output latches '151 and input multiplexors but cant seem to get what i need... ????? |
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#3
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Digital I/O Expansion
Dan,
It is a small embedded controller. I have to design an interface board anyway. Problem is mainly with the outputs now. I cant figure out how to expand the 4 into a greater number. Im am not worried about the software end of it.. "Dan Hollands" wrote in message .. . Hard to offer any advice when you give no clue as to the type of system you are talking about Computer Data Logger Controller of some type etc -- Dan Hollands 1120 S Creek Dr Webster NY 14580 585-872-2606 www.QuickScoreRace.com "David Andrews" wrote in message news:tpS7f.9607$%A1.9383@trndny01... I have to expand i/o on a system that now has only 4 inputs and 4 outputs. I need 12 inputs and 13 outputs. Anybody got any ideas, i thought this would be easier. Im familiar with the '249 output latches '151 and input multiplexors but cant seem to get what i need... ????? |
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#4
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Digital I/O Expansion
"David Andrews" wrote in message news:7yc8f.14224$%A1.10257@trndny01... Dan, It is a small embedded controller. I have to design an interface board anyway. Problem is mainly with the outputs now. I cant figure out how to expand the 4 into a greater number. Im am not worried about the software end of it.. "Dan Hollands" wrote in message .. . Hard to offer any advice when you give no clue as to the type of system you are talking about Computer Data Logger Controller of some type etc -- Dan Hollands 1120 S Creek Dr Webster NY 14580 585-872-2606 www.QuickScoreRace.com "David Andrews" wrote in message news:tpS7f.9607$%A1.9383@trndny01... I have to expand i/o on a system that now has only 4 inputs and 4 outputs. I need 12 inputs and 13 outputs. Anybody got any ideas, i thought this would be easier. Im familiar with the '249 output latches '151 and input multiplexors but cant seem to get what i need... ????? Would a binary to decimal decoder work? Program the four outputs to be 4bit binary numbers and end up with 16 outputs? Look at truth table for Fairchild's DM74LS154 chip. Bart |
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#5
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Digital I/O Expansion
On 2005-10-26, David Andrews wrote:
I have to expand i/o on a system that now has only 4 inputs and 4 outputs. I need 12 inputs and 13 outputs. Anybody got any ideas, i thought this would be easier. Im familiar with the '249 output latches '151 and input multiplexors but cant seem to get what i need... ????? use two of your pins one to clock and one to sense state zero on a counter that gives you a sequential address scanner... your 6 remaining lines are inputs and outputs to those addresses. -- Bye. Jasen |
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