Switch between different sets of inputs

I have a pic micro controller that is hooked up to 5 devices that each have 7 wires for control. Only 1 device needs to be used at a time. I don't have 5*7 = 35 ports on my pic. How can use less pins on my pic? I'm thinking something like a multiplexer would help but I'm not sure how to implement it in this case.

Which PICmicro are you using? You can use 5 octal latch ICs (like 74LS373), each for individual device control signals. All the inputs of latches will be connected in parallel. This way, you can send 7 control signals to all devices but it will be received by only one whose Latch Circuit is Output Enabled. Check datasheets for 74LS373. Also check for 74LS273.

- Raj
Experiments with PIC16F628A

Powzoom said:

I have a pic micro controller that is hooked up to 5 devices that each have 7 wires for control. Only 1 device needs to be used at a time. I don't have 5*7 = 35 ports on my pic. How can use less pins on my pic? I'm thinking something like a multiplexer would help but I'm not sure how to implement it in this case.

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Can you have an enable line for each device? Then you could connect the 7 wires to all the 5 devices, and 5 enable wires. Total of 12 ports.

someting I made up quick, It might help


Sorry 48 Input ports - it was late...