I have followed the very first example provided from the “STEP-MXO2 Software Manual”. It is a AND function. But when I have done and burned into the STEP board, I have the impression it is an OR gate instead. Because when none the 2 button is pressed, the LED is off, when any or all of the 2 buttons is pressed the LED is on. Anyone there please help to explain. Many thanks
Got the following infor from the “STEP-MXO2 V2 software manual”:
When the single of LED on the STEP-FPGA is low, the led will be brighten, and initial state of button is high, when you push it, the single of button is low.
So, when the FPGA is running, the led will be brighten if you push any button.
1. LED is active LOW. When FPGA gives an output LOW, so the connected LED is on! And when the FPGA delivers an logic HIGH output, the connected LED is off.
2. For the push buttons, they give HIGH output when NOT being pressed down. And when a button is pressed, it provides a LOW output
This is basic defenition of boolean logic.
NOT (AND(NOT A,NOT B)) equal OR(A,B)
NOT ((NOT 0) AND (NOT 0)) = 0 = 0 OR 0
NOT ((NOT 1) AND (NOT 0)) = 1 = 1 OR 0
NOT ((NOT 0) AND (NOT 1)) = 1 = 0 OR 1
NOT ((NOT 1) AND (NOT 1)) = 1 = 1 OR 1
In MAX10 boards i have some problem, invers signals from buttons and LEDs.