Dinx4 and midio 128

[superdavies]

Hi everybody

Just a simple question: I'm building a midio128 and i'm connecting the 4 dinx4 module together for having the 128 digital imput (normal midification of a double keyboard). In the page of the din module I find this in the part that talk about the components and I can't understand: "If you are using the DIN module with a MIDIO128, you maybe want to drive the pins "high-active" (which means: +5V = on, 0V = off). In this case please solder the two red isolated cables not to 5V, but to 0V (Vss), so that the resistors act as pull-downs"  What does it means? Where are the two red isolated cables? I see the schematics for connecting 32 buttons on a din, what's the difference in this new configuration?

Thank you in advance!!!

Andrea

[jimhenry]

Just trying to answer the "maybe you want to drive the pins active high" part. If the answer is no, you can ignore the rest.

A DIN reads a digital input meaning an input that has only two states, ON or OFF. The two states need to be represented by two voltages, +5 volts (the power voltage for the Midibox) and 0 volts (the Midibox ground). The usual way to read a simple switch is to connect one side of the switch to ground and the other side to the DIN input pin. When the switch is closed, the input will be 0 volts. To get the +5 volts when the switch is open, the input pin is also connected to a resistor that is connected to +5 volts at the other end. This resistor is on the DIN board. The resistor has enough resistance that it won't supply any appreciable amount of current when the switch is closed. The result is an input for the DIN pin that is +5 volts when the switch is open and 0 volts when the switch is closed.

If for some reason you wanted to connect your switch to +5 volts instead of ground, then you need to reverse the voltage on the other end of the resistor. This would be the "drive the pins active high" configuration.