Primitive: Bi-Directional Differential Buffer with DCI Enable/Disable and Input Disable
This design element is a bidirectional differential I/O buffer used to connect internal logic to an external bidirectional pin. This element includes Digitally Controlled Impedance (DCI) termination enable/disable as well as input path disable as additional power saving features when the I/O is either in an unused state or being used as an output for a sustained amount of time. This element may only be placed in High Performance (HP) banks in the 7 series devices.
|IO||In/out||1||Bi-directional p-side port connection. Connect directly to top-level port in the design.|
|IOB||In/out||1||Bi-directional p-side port connection. Connect directly to top-level port in the design.|
|I||Input||1||Buffer input representing the output path to the device.|
|IBUFDISABLE||Input||1||Disables input path. When this signal is asserted HIGH and the attribute USE_IBUFDISABLE is set to "TRUE", the input path through the input buffer is disabled and forced to a logic HIGH.. If USE_IBUFDISABLE is set to "FALSE" this input is ignored and should be tied to ground. This feature is generally used to reduce power at times when the I/O is either idle or during sustained write (output) conditions.|
|DCITERMDISABLE||Input||1||Disables DCI termination. When this signal is asserted HIGH, DCI termination is disabled. This feature is generally used to reduce power at times when the I/O is either idle or during sustained write (output) conditions.|
|T||Input||1||Sets the I/O in a high impedance 3-state mode when the I/O is being used for a read (input) operation. The T pin also affects the IBUFDISABLE function when USE_IBUFDISABLE = "TRUE".|
|O||Output||1||Buffer output representing the input path to the device.|
Design Entry Method
|DIFF_TERM||STRING||"TRUE", "FALSE"||"FALSE"||Turns the built-in differential termination on (TRUE) or off (FALSE).|
|IBUF_LOW_PWR||STRING||"TRUE", "FALSE"||"TRUE"||Allows a trade off of lower power consumption vs. highest performance.|
|IOSTANDARD||STRING||See Data Sheet||"DEFAULT"||Assigns an I/O standard to the element.|
|SLEW||STRING||"SLOW", "FAST",||"SLOW"||Sets the output rise and fall time. See the Data Sheet for recommendations of the best setting for this attribute.|
|USE_IBUFDISABLE||STRING||"TRUE", "FALSE"||"TRUE"||Enables or disables the feature of IBUFDISABLE. Set to FALSE when it is not desirable to have the T pin disable input path to allow a read during write operation. When set to TRUE deasserting T (IO used as output) or asserting IBUFDISABLE will disable the input path through the buffer and forces to a logic high.|
VHDL Instantiation Template
Unless they already exist, copy the following two statements and paste them before the entity declaration.
Library UNISIM; use UNISIM.vcomponents.all;
-- IOBUFDS_DCIEN: Differential Bi-directional Buffer with Digital Controlled Impedance (DCI) -- and Input path enable/disable -- May only be placed in High Performance (HP) Banks -- 7 Series -- Xilinx HDL Language Template, version 2021.2 IOBUFDS_DCIEN_inst : IOBUFDS_DCIEN generic map ( DIFF_TERM => "FALSE", -- Differential termination (TRUE/FALSE) IBUF_LOW_PWR => "TRUE", -- Low Power - TRUE, HIGH Performance = FALSE IOSTANDARD => "BLVDS_25", -- Specify the I/O standard SLEW => "SLOW", -- Specify the output slew rate USE_IBUFDISABLE => "TRUE") -- Use IBUFDISABLE function "TRUE" or "FALSE" port map ( O => O, -- Buffer output IO => IO, -- Diff_p inout (connect directly to top-level port) IOB => IOB, -- Diff_n inout (connect directly to top-level port) DCITERMDISABLE => DCITERMDISABLE, -- DCI Termination enable input I => I, -- Buffer input IBUFDISABLE => IBUFDISABLE, -- Input disable input, high=disable T => T -- 3-state enable input, high=input, low=output ); -- End of IOBUFDS_DCIEN_inst instantiation
Verilog Instantiation Template
// IOBUFDS_DCIEN: Differential Bi-directional Buffer with Digital Controlled Impedance (DCI) // and Input path enable/disable // May only be placed in High Performance (HP) Banks // 7 Series // Xilinx HDL Language Template, version 2021.2 IOBUFDS_DCIEN #( .DIFF_TERM("FALSE"), // Differential Termination ("TRUE"/"FALSE") .IBUF_LOW_PWR("TRUE"), // Low Power - "TRUE", High Performance = "FALSE" .IOSTANDARD("BLVDS_25"), // Specify the I/O standard .SLEW("SLOW"), // Specify the output slew rate .USE_IBUFDISABLE("TRUE") // Use IBUFDISABLE function, "TRUE" or "FALSE" ) IOBUFDS_DCIEN_inst ( .O(O), // Buffer output .IO(IO), // Diff_p inout (connect directly to top-level port) .IOB(IOB), // Diff_n inout (connect directly to top-level port) .DCITERMDISABLE(DCITERMDISABLE), // DCI Termination enable input .I(I), // Buffer input .IBUFDISABLE(IBUFDISABLE), // Input disable input, high=disable .T(T) // 3-state enable input, high=input, low=output ); // End of IOBUFDS_DCIEN_inst instantiation
- See the 7 Series FPGA SelectIO Resources User Guide (UG471).