RPi GPIO Test #2: Loopback Testing

In this system configuration (GPIO_TEST), the Raspberry Pi GPIO configuration and loopback connection are identical to those of the previous example, with the addition of HMI elements such that the operation is as follows:

• Clicking on the OUTPUT check box causes the OUTPUT.OUT value to flip; this value is passed to the PIN3.X input.
• An event is passed from OUTPUT.IND to PIN3.REQ; this causes the flipped value at PIN3.X to be written to pin 3 of the Raspberry Pi 2 GPIO header.
• The output state is passed electrically from pin 3 to pin 5 of the GPIO header.
• An event is passed from PIN3.CNF to PIN5.REQ, which causes the value of the input at pin 5 of the header to appear at PIN5.X, which is passed to INPUT.IN.
• An event is passed from PIN5.CNF to INPUT.REQ, which causes the INPUT display to be updated with the new value of PIN5.IN.