Description
A net is a set of interconnected pins, ports, and wires. Every wire has a net name, which identifies it. Two or more wires can have the same net name. All wires sharing a common net name are part of a single NET, and all pins or ports connected to these wires are electrically connected.
A default net name is assigned to the NET object as it is added to the netlist design during elaboration or compilation of the RTL source files into a netlist design. You can also manually assign names to nets.
Nets can either be scalar nets, with a single signal, or can be bus nets, which are groups of scalar nets with multiple signals. Buses are a convenient way to group related signals, allowing a less cluttered, more understandable schematics. It also clarifies the connection between the main circuit and a block symbol. Buses are especially useful for the following:
- Routing a number of signals from one side of the schematic to the other
- Connecting more than one signal to a block symbol
- Connecting more than one signal to pass between hierarchical levels by connecting to a single I/O marker
Related Objects
In the design netlist, a NET can be connected to the PIN of a CELL, or to a PORT. Net objects are also associated with CLOCKs brought onto the design through PORTs, and to TIMING_PATHs in the design. NETs can also be associated with DRC_VIOLATIONs to allow you to more quickly locate and resolve design issues. You can query the nets associated with these different design objects:
get_nets -of [get_cells dbg_hub]As the design is mapped onto the target AMD FPGA, the NET is mapped to routing resources such as WIREs, NODEs, and PIPs on the device, and is connected to BELs through BEL_PINs, and to SITEs through SITE_PINs. You can query the clock, pin, port, bel, bel_pin, site, site_pin, tile, node, pip, wire associated with a specific net or nets in the design:
get_bel_pins -of [get_nets ddr4_sdram_adr[0]]Properties
The specific properties on a net object can vary depending on the type of net the object represents. The following table lists some of the properties assigned to a net object in the Vivado Design Suite, with example values:
Property Type Read-only Visible Value
AREA_GROUP string true true
BEL string true true
BLKNM string true true
BUFFER_TYPE enum false true
BUFG enum true true
BUS_NAME string true true DataIn_pad_0_i
BUS_START int true true 7
BUS_STOP int true true 0
BUS_WIDTH int true true 8
CLASS string true true net
CLOCK_BUFFER_TYPE enum false true
CLOCK_DEDICATED_ROUTE enum false true
CLOCK_REGION_ASSIGNMENT string false true
CLOCK_ROOT string* false true
COLLAPSE bool true true
COOL_CLK bool true true
DATA_GATE bool true true
DCI_VALUE int false true
DIFF_TERM bool false true
DIRECT_ENABLE bool false true
DIRECT_RESET bool false true
DONT_TOUCH bool false true
DRIVE int true false
DRIVER_COUNT int true true 1
ESSENTIAL_CLASSIFICATION_VALUE int false true
FILE_NAME string true true
FIXED_ROUTE string false true
FLAT_PIN_COUNT int true true 1
FLOAT bool true true
GATED_CLOCK bool false true
HBLKNM string true true
HD.NO_ROUTE_CONTAINMENT bool false true
HIERARCHICALNAME string true false top.DataIn_pad_0_i[0]
HU_SET string true false
IBUF_DELAY_VALUE double true true
IBUF_LOW_PWR bool false true
IFD_DELAY_VALUE double true true
IN_TERM enum true true
IOB enum false true
IOBDELAY enum false true
IOSTANDARD string true false LVCMOS18
IO_BUFFER_TYPE enum false true
IS_CONTAIN_ROUTING bool true true 0
IS_INTERNAL bool true true 0
IS_REUSED bool true true 0
IS_ROUTE_FIXED bool false true 0
KEEP bool true true
KEEPER bool true true
LINE_NUMBER int true true
LOC string true true
MARK_DEBUG bool false true 0
MAXDELAY double true true
MAXSKEW double true true
MAX_FANOUT string false true
METHODOLOGY_DRC_VIOS string false true
MULTI_CLOCK_ROOT string* false true
NAME string true true DataIn_pad_0_i[0]
NODELAY bool true true
NOREDUCE bool true true
OUT_TERM enum true true
PARENT string true true DataIn_pad_0_i[0]
PARENT_CELL string true true
PIN_COUNT int true true 1
PULLDOWN bool true true
PULLUP bool true true
PWR_MODE enum true true
RAM_STYLE enum false true
REUSE_STATUS enum true true
RLOC string true true
RLOC_ORIGIN string true false
RLOC_RANGE string true false
ROM_STYLE enum false true
ROUTE string false true
ROUTE_STATUS enum true true INTRASITE
RPM_GRID enum true true
RTL_KEEP string true false
RTL_MAX_FANOUT string true false
S bool true true
SCHMITT_TRIGGER bool true true
SLEW string true true
SUSPEND string true true
TYPE enum true true SIGNAL
USELOWSKEWLINES bool true true
USE_DSP48 enum false true
U_SET string true false
WEIGHT int false true
WIREAND bool true true
XBLKNM string true true
XLNX_LINE_COL int false false
XLNX_LINE_FILE long false false
_HAVE_MD_DT bool true false
async_reg string false true
To report the properties for a net object, you can copy and paste the following command into the Vivado Design Suite Tcl shell or Tcl Console:
report_property -all [lindex [get_nets] 0]