Scanning 40 keys......?

[jit_singh_tara]

What would be the best method for scanning 40 keys using pic microcontroller :

1.interrupt based using multiple port expanders mcp23017 or mcp23s17.

2.Using a dedicated controller for key scanning and sending data using rs232 tx pin.

3.Any other method.

 

[IanP]

That depends on how far are you going to be involved in this ..

If you think you can do it by yourself then this option:

1.interrupt based using multiple port expanders mcp23017 or mcp23s17.

looks reasonable ..

Rgds,
IanP
:|

 

[anandpv2009]

What would be the best method for scanning 40 keys using pic microcontroller :

1.interrupt based using multiple port expanders mcp23017 or mcp23s17.

2.Using a dedicated controller for key scanning and sending data using rs232 tx pin.

3.Any other method.

I prefer dedicated controller.

1. Scanning
2. Pressed->interrupt master controller <10ms delay/debounce>--->send 8bit address to master corresponding to pressed key