NanoBoard 3000 - Generic User Switches

Frozen Content

Modified by Admin on Sep 13, 2017

The NanoBoard 3000 provides a further five push button style switches that are wired to separate I/O pins of the User FPGA. They can be used as generic switch inputs to a design.

PDA-style push buttons.

Each switch is of type SPNO – Single Pole Normally Open. In the open position, it provides a logical High signal to the FPGA device, changing to logical Low when pressed.

The five switch signals arrive at the User FPGA as signals SW0 to SW4. On the motherboard, SW0 is the signal associated with switch number 1, in the left-most position.

The switch signals are also made available at pins 1-5, respectively, of an FFC 2x20 pin connector, labeled 'SWITCH&LED IO'. This connector provides convenient exposure not only of these generic switch signals, but also signals relating to the board's RGB User LEDs.

1.8" ATA/IDE interface
connector for accessing
switch and LED I/O.

Location on the Board

The switches (designated SW1 - SW5) are located on the component side of the board, below the NanoTalk Controller FPGA (U30).

The 'SWITCH&LED IO' connector (designated J28) is located on the component side of the board, to the left of the User FPGA (U8) and below the backup battery for the board's Real-Time Clock.

Schematic Reference

The switches can be found on the following sheets of the motherboard schematics:

Sheet 35 (SW_PB_SPNOx5_SMD.SchDoc, entitled PDA-Style 5 x SPNO Switch)

Sheet 36 (CON_NB3000_LEDKB.SchDoc, entitled LED and Button Ext. Connector) – showing the 40-pin connector from where the generic switch signals are made externally available.

Design Interface Component

Table 1 summarizes the available design interface components that can be placed from the FPGA NB3000 Port-Plugin.IntLib, to access and use the push button switches, SW1 - SW5.

Table 1. User switches port-plugin components.

Component Symbol	Component Name	Description
	`USER_BUTTONS`	Place this component to use all five push button switches (`SW1` - `SW5`) in your FPGA design.
	`USER_BUTTON0`	Place this component to use push button switch `SW1` in your FPGA design.
	`USER_BUTTON1`	Place this component to use push button switch `SW2` in your FPGA design.
	`USER_BUTTON2`	Place this component to use push button switch `SW3` in your FPGA design.
	`USER_BUTTON3`	Place this component to use push button switch `SW4` in your FPGA design.
	`USER_BUTTON4`	Place this component to use push button switch `SW5` in your FPGA design.

Although the five signals arrive at the User FPGA device on separate pins, the USER_BUTTONS interface component provides a 5-bit bus input. Connection to the component's bus port depends on where in the design these signals are destined. If, for example, you wanted to use single switch signals in different areas of the design, you would need to use an appropriate bus joiner device.

Remember that each switch provides a Low signal when pressed. If you require a signal that goes High when the corresponding switch is pressed, you will need to place an inverter component within your design accordingly.

For more information on the available bus joiner and inverter components available for use in an FPGA design, refer to the Functional Classes – Bus Joiner and Functional Classes – Inverter sections of the FPGA Generic Library Guide respectively.