What is the threshold voltage when reading an input to the SSC-32? What voltage will be interepreted as High, what will be interpreted as low? This refers to commands like the A or AL command for binary reads. Thanks!
The SSC-32 uses processor inputs in digital mode for the A and AL type commands, so the thresholds are based on the input pin characteristics of the ATmega8 processor. At room temperature the typical thresholds would be about 1.4V for logic ‘0’ and 1.8V for logic ‘1’. The pins have about 0.4V hysteresis, so if the input is between 1.4 and 1.8V it will keep its previous value.
In case you are not familiar with hysteresis, the interpretation of the numbers above would be this. If the voltage on the input pin slowly rises from 0V, the logic value would be ‘0’ until the voltage reaches 1.8V, at which time it would change to logic ‘1’. If the voltage then begins to decrease, the logic value would remain at ‘1’ until the voltage got to 1.4V, at which time it would change to logic ‘0’. The threshold is different for a 0->1 transition than for a 1->0 transition. This keeps the input from chattering back and forth when the input is close to the threshold value.
The numbers above are typical values at room temperature. The datasheet also has guaranteed values over the entire temperature range. They guarantee that any input less than 1V will read as a logic ‘0’, and any input greater than 3V will read as logic ‘1’.
I hope this helps.