Other Special Components

In this section, you complete the Calc design by adding a STARTUP symbol to make the logic resetable and a CONFIG symbol to specify the Xilinx part number on the schematic.

The STARTUP Block (Optional: XC4000E/EX and XC5200 only)

The STARTUP block allows you to globally control different aspects of a design. This example uses STARTUP to connect an external signal to the global set/reset net built into the XC4000 family and XC5200 architectures. This global net connects to all flip-flops in the device and sets or resets them asynchronously. (Set or reset is determined at the flip-flop level.) An advantage to using this built-in resource is that no routing resources are wasted tying a system-wide reset signal to all flip-flops in the design. For more information on STARTUP, see the Xilinx Libraries Guide.

The STARTUP symbol is used here to implement a system-wide reset signal called NOTGBLRESET. This signal is active-low; therefore, when NOTGBLRESET is low, the Calc circuitry is reset.

1. In the Calc schematic, add the components, nets, and labels as shown in the following figure.
   
   You may take IPAD and IBUF from the BY TYPE io section of the Xilinx Library, INV from BY TYPE logic, and STARTUP from BY TYPE general.
   
   

   Figure 9.51 Adding the STARTUP Symbol

   An inverter is added to the signal path since the GSR pin on STARTUP is active-high. Also, since GSR is implicitly connected to all reset logic throughout the device, GBLRESET is connected only to the GSR pin on the schematic.
   
   

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   NOTE

   If you target an XC5200 device, connect your chip-wide reset signal to the GR pin on the STARTUP module.

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2. Check and save the Calc design.
   
   

Adding the CONFIG Symbol (Optional)

The CONFIG symbol tells the place-and-route software how to process the design. This example uses CONFIG to specify the part number for this device.

To add the CONFIG symbol, follow these steps.

1. From the Calc schematic use the BY TYPE general menu to call up the CONFIG symbol from the Xilinx Library.
   
   
2. Place this symbol in the lower-right hand corner of the Calc schematic.
   
   
3. With the CONFIG symbol still highlighted, select Right Mouse Button Properties Add Add Single Property.
   
   
4. In the Add Property dialog box, enter the Property Name as “PART” and the Property Value as “XC4003E-4-PC84” and click OK.
   
   This specifies an XC4003E device with -4 speed grade (approximately 4 nanoseconds delay through a CLB) in an 84-pin PLCC.
   
   The PART value may take one of the following two formats:
   
   [XC] part_number-speed-package
   [XC] part_number-package-speed
   
   Therefore, the following values for the PART property are all legal:
   
   XC4003E-4-PC84 (recommended)
   XC4003E-PC84-4
   4003E-4-PC84
   4003E-PC84-4
   
   

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   NOTE

   If using a different device, type that device number into the Property Value field instead, e.g., XC95108-10-PC84

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5. Place the property text within the CONFIG symbol as shown in the following figure.
   
   

   Figure 9.52 Adding the CONFIG Symbol

6. Check and save the Calc schematic.