AN 265: Using Altera MAX Series as Microcontroller I/O Expanders

ID 683386
Date 9/22/2014
Public

1.5.1. Simulating Microcontroller I/O Expander Write Mode Timing

Figure 2. Write Mode Timing Simulation of the Microcontroller I/O Expander


  1. With all the I/O pins in tri-state mode, initialize each port.
  2. After initialization, configure port A and port B as output, and port C and port D as input.
  3. Enable port B for write operation.
    When WR asserts a low signal, the clock through the output data registers is enabled and creates a new output value (146) at the output port B from the MCU port.
  4. Once the LOAD signal asserts low, enable port A.
    When the WR signal is low to enable the clock through the output data registers, the MCU port data (108) is created at the output port A.