Logic Symbols.

Presentation on theme: "Logic Symbols."— Presentation transcript:

Logic Symbols

Analog and Digital In a Crestron World
For Crestron programming purposes Digital is single digit Binary (1/0, On/Off) Analog is 16 bit Binary, Decimal or Hex

Digital Decisions Digital decisions are made by logic “elements” or “gates” A logic element will have it’s output state determined by the state of it’s inputs The most basic gates are: AND OR NOT

OR + This gate may have 2 or more inputs
A + B B This gate may have 2 or more inputs The output is “true” when any input is true The + sign represents OR A + B means A or B

AND . This gate may have 2 or more inputs
A . B B This gate may have 2 or more inputs The output is “true” when ALL inputs are true The . sign represents AND A . B means A AND B

______ NOT This gate has only 1 input
This is sometimes called an INVERTER The output is true when the input is not true ___ The represents NOT _ A means NOT A

Truth Tables Truth Tables are useful in determining the action of a logic symbol A truth table shows all combinations of inputs and the corresponding output for each.

AND Truth Table Input A B Output A AND B 1

OR Truth Table Input A B Output A OR B 1

NOT Truth Table A _ 1

Make your own Truth Table or Logic Statement
Given a scenario, if you can create a truth table or a “logic statement”, it will help to create the program logic. Example: You want the DVD power on to work only before 11:00 at night so the kids don’t stay up late. You also want the DVD power button to be smart, meaning not to power off if you mean to leave it on.

Assumptions You have a signal from the built in clock that tells you it is after 11:00 (ELEVEN) You have a signal from i/o port 1 that tells you the DVD Power is On (DVD_ON) The touchpanel signal from press-join 10 is called DVDPOWERON

Start a statement You need to send out the power signal to the DVD player when it is before 11:00 and someone pushes the DVD power on button and the DVD player is off. Make the statement more of an equation DVDPOWER = DVDPOWERON and NOT DVD_ON and NOT ELEVEN

Truth Table DVDPOWER = DVDPOWERON and NOT DVD_ON and NOT ELEVEN
1

Truth Table DVDPOWER = DVDPOWERON and NOT DVD_ON and NOT ELEVEN
1

Draw the Logic From statement or truth table or both, develop the logic diagram DVDPOWERON AND ELEVEN NOT DVDPOWER DVDON NOT

Program the logic

Use a Truth Table Symbol
Crestron has a truth table symbol It may be easier than building your own logic You still have to understand the logic to make the truth table correct