But recall the Verilog description is only part of the solution - we must also connect the “logical” circuit names in our design (i.e., sw and led) to the physical pins on the Xilinx device – in this case, to the pins connected to the switch and LED we wish to use. Only a single assign statement is needed in the Verilog code to connect the “sw” input to the “led” output, and this is shown below. The input port is called “sw”, and the output port is called “led”. We will build a simple circuit called led_sw that passes a signal through the FPGA, from an input slide switch to an output LED, without using any other components. In this tutorial, a slide switch is used as an input device, and an LED is used as an output. Your Real Digital board contains several input and output devices that can produce and consume I/O port signals. Likewise, there are many devices that might receive output port signals, like LEDs, speakers, actuators, other electronic devices, etc. There are many devices and sources that can drive input port signals, including pushbuttons, slide switches, keyboards, touch panels, other electronic devices. In the example circuit shown below, the input port signals A, B, and C are connected to pushbuttons, and the output ports are connected to LEDs. Within the digital circuit, there are typically several signals that transport information between devices inside the circuit, and that never see the outside world and there are several signals called ports that communicate with the outside world. Although signals are wires that transport voltage, we tend to think of digital signals as transporting information (a ‘0’ or a’1’).Ī digital circuit combines and manipulates information transported by input signals (‘0’ or ‘1’) using various logical constructs like AND’ing or OR’ing, and produces one or more output signals that return information to the “outside world”. Recall digital signals are voltage signals that are constrained to be at the circuits “high” voltage (typically 3.3V, also called a ‘1’), or the circuits “low” voltage (or ground, also called a ‘0’). This simple exercise is intended to demonstrate how input and output devices are connected to your circuits – in the next exercise, you will add logic circuits between the inputs and outputs.ĭigital circuits receive information from the “outside world” in the form of digital signals. In this tutorial, slide switch inputs are connected through the FPGA to the LED outputs, without any logic in between. This case, also known as a "default" case, will fire if the first case's condition doesn't pass (when the page is scrolled up past Y=200).This second tutorial demonstrates how to describe a basic digital circuit using Verilog, and in particular, how to connect circuit inputs and outputs to physical devices on the Boolean board. Notice that even though we didn't set up a condition for this case, it has the condition ELSE IF true. In the Condition Builder dialog that appears, name the case Scroll Up and click OK without adding any logic. Back in Axure RP, hover over the Window Scrolled heading in the Interactions pane and click Add Case to the right.Show the Scrolling Header Again When the Page Is Scrolled Up Add a Second Window Scrolled Case The header should stick in place once it reaches the top of the page.Ĥ. Hiding that group and showing the Sticky Header dynamic panel at the same time will give the appearance that the header has stopped scrolling.Ĭlick OK to close the Condition Builder dialog. This condition will be met when the page has been scrolled 200 pixels downward, which is precisely when the Scrolling Header group, located at (0,200), will reach the top of the page. The summary at the bottom of the Condition Builder dialog should now read: if "]" is greater than or equals "200". In the condition row's third field, select is greater than or equals. (This bracketed expression represents the number of pixels the page has been scrolled vertically in the web browser.) The field at the top of the dialog should now read: ]. In the list that appears, select Window.scrollY under the Window heading. Then click the fx icon to the right of the second field to open the Edit Text dialog.Īt the top of the dialog, click Insert Variable or Function. In the condition row that appears, select value in the first dropdown. In the Condition Builder dialog that appears, name the case Scroll Down and click Add Logic. Hover over the Window Scrolled heading in the Interactions pane and click Enable Cases to the right. Add a Condition That Checks the Page's Scroll Position
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