XPM_MEMORY_DPDISTRAM - 2022.2 English

Parameterized Macro: Dual Port Distributed RAM

MACRO_GROUP: XPM
MACRO_SUBGROUP: XPM_MEMORY

Introduction

This macro is used to instantiate Dual Port Distributed RAM. Port-A can be used to perform both read and write operations and simultaneously port B can be used to perform read operations from the memory. Write operations are not allowed through port B.

The following describes the basic read and write port usage of an XPM_MEMORY instance. It does not distinguish between ports A and B.

All synchronous signals are sensitive to the rising edge of clk[a|b], which is assumed to be a buffered and toggling clock signal behaving according to target device and memory primitive requirements.
A read operation is implicitly performed to address addr[a|b] combinatorially. The data output is registered each clk[a|b] cycle that en[a|b] is asserted.
Read data appears on the dout[a|b] port READ_LATENCY_[A|B] clk[a|b] cycles after the associated read operation.
A write operation is explicitly performed, writing dina to address addra, when both ena and wea are asserted on each clka cycle.
All read and write operations are gated by the value of en[a|b] on the initiating clk[a|b] cycle, regardless of input or output latencies. The addra and wea inputs have no effect when ena is de-asserted on the coincident clka cycle.
For each clk[a|b] cycle that rst[a|b] is asserted, the final output register is immediately but synchronously reset to READ_RESET_VALUE_[A|B], irrespective of READ_LATENCY_[A|B].
For each clk[a|b] cycle that regce[a|b] is asserted and rst[a|b] is de-asserted, the final output register captures and outputs the value from the previous pipeline register.
Undriven or unknown values provided on module inputs will produce undefined memory array and output port behavior.
When MEMORY INIT PARAM is used, the maximum supported memory size 4K bits.

Note:

When the attribute “CLOCKING_MODE” is set to “common_clock”, all read/write operations to memory through port A and port B are performed on clka. If this attribute is set to “independent_clock”, then read/write operations through port A are performed based on clka, and read/write operations through port B are performed based on clkb.
Writing to an out-of-range address location may overwrite a valid address location when effective address bits match to a physical memory address location.
set_false_path constraint is needed for the independent clock distributed RAM based memory if the design takes care of avoiding address collision (write address != read address at any given point of time). Set USE_EMBEDDED_CONSTRAINT = 1 if XPM_MEMORY needs to take care of necessary constraints. If USE_EMBEDDED_CONSTRAINT = 0, Vivado may trigger Timing-6 or Timing-7 or both. Alternatively, you can also add the constraint when USE_EMBEDDED_CONSTRAINT = 0. An example of adding this constraint is provided below. If Port-B also has write permissions for an Independent clock configuration, then a similar constraint needs to be added for clkb as well.
```
set_false_path -from [filter [all_fanout -from [get_ports clka]
-flat -endpoints_only] {IS_LEAF}] -through [get_pins -of_objects
[get_cells -hier * -filter {PRIMITIVE_SUBGROUP==LUTRAM ||
PRIMITIVE_SUBGROUP==dram || PRIMITIVE_SUBGROUP==drom}]
-filter {DIRECTION==OUT}]
```
If "CLOCKING_MODE" is set to "independent_clock", Vivado may trigger a false positive CDC-1 warning and can be ignored.

Port Descriptions

Port	Direction	Width	Domain	Sense	Handling if Unused	Function
addra	Input	ADDR_WIDTH_A	clka	NA	Active	Address for port A write and read operations.
addrb	Input	ADDR_WIDTH_B	clkb	NA	Active	Address for port B write and read operations.
clka	Input	1	NA	EDGE_RISING	Active	Clock signal for port A. Also clocks port B when parameter CLOCKING_MODE is "common_clock".
clkb	Input	1	NA	EDGE_RISING	Active	Clock signal for port B when parameter CLOCKING_MODE is "independent_clock". Unused when parameter CLOCKING_MODE is "common_clock".
dina	Input	WRITE_DATA_WIDTH_A	clka	NA	Active	Data input for port A write operations.
douta	Output	READ_DATA_WIDTH_A	clka	NA	Active	Data output for port A read operations.
doutb	Output	READ_DATA_WIDTH_B	clkb	NA	Active	Data output for port B read operations.
ena	Input	1	clka	LEVEL_HIGH	Active	Memory enable signal for port A. Must be high on clock cycles when read or write operations are initiated. Pipelined internally.
enb	Input	1	clkb	LEVEL_HIGH	Active	Memory enable signal for port B. Must be high on clock cycles when read or write operations are initiated. Pipelined internally.
regcea	Input	1	clka	LEVEL_HIGH	1	Clock Enable for the last register stage on the output data path.
regceb	Input	1	clkb	LEVEL_HIGH	Active	Do not change from the provided value.
rsta	Input	1	clka	LEVEL_HIGH	Active	Reset signal for the final port A output register stage. Synchronously resets output port douta to the value specified by parameter READ_RESET_VALUE_A.
rstb	Input	1	clkb	LEVEL_HIGH	Active	Reset signal for the final port B output register stage. Synchronously resets output port doutb to the value specified by parameter READ_RESET_VALUE_B.
wea	Input	WRITE_DATA_WIDTH_A / BYTE_WRITE_WIDTH_A	clka	LEVEL_HIGH	Active	Write enable vector for port A input data port dina. 1 bit wide when word-wide writes are used. In byte-wide write configurations, each bit controls the writing one byte of dina to address addra. For example, to synchronously write only bits [15-8] of dina when WRITE_DATA_WIDTH_A is 32, wea would be 4'b0010.

Design Entry Method

Instantiation	Yes
Inference	No
IP and IP Integrator Catalog	No

Available Attributes

Attribute	Type	Allowed Values	Default	Description
ADDR_WIDTH_A	DECIMAL	1 to 20	6	Specify the width of the port A address port addra, in bits. Must be large enough to access the entire memory from port A, i.e. >= $clog2(MEMORY_SIZE/[WRITE\|READ]_DATA_WIDTH_A).
ADDR_WIDTH_B	DECIMAL	1 to 20	6	Specify the width of the port B address port addrb, in bits. Must be large enough to access the entire memory from port B, i.e. >= $clog2(MEMORY_SIZE/[WRITE\|READ]_DATA_WIDTH_B).
BYTE_WRITE_WIDTH_A	DECIMAL	1 to 4608	32	To enable byte-wide writes on port A, specify the byte width, in bits. 8- 8-bit byte-wide writes, legal when WRITE_DATA_WIDTH_A is an integer multiple of 8 9- 9-bit byte-wide writes, legal when WRITE_DATA_WIDTH_A is an integer multiple of 9 Or to enable word-wide writes on port A, specify the same value as for WRITE_DATA_WIDTH_A.
CLOCKING_MODE	STRING	"common_clock", "independent_clock"	"common_clock"	Designate whether port A and port B are clocked with a common clock or with independent clocks- "common_clock"- Common clocking; clock both port A and port B with clka "independent_clock"- Independent clocking; clock port A with clka and port B with clkb
MEMORY_INIT_FILE	STRING	String	"none"	Specify "none" (including quotes) for no memory initialization, or specify the name of a memory initialization file- Enter only the name of the file with .mem extension, including quotes but without path (e.g. "my_file.mem"). File format must be ASCII and consist of only hexadecimal values organized into the specified depth by narrowest data width generic value of the memory. Initialization of memory happens through the file name specified only when parameter MEMORY_INIT_PARAM value is equal to "". When using XPM_MEMORY in a project, add the specified file to the Vivado project as a design source.
MEMORY_INIT_PARAM	STRING	String	"0"	Specify "" or "0" (including quotes) for no memory initialization through parameter, or specify the string containing the hex characters. Enter only hex characters with each location separated by delimiter (,). Parameter format must be ASCII and consist of only hexadecimal values organized into the specified depth by narrowest data width generic value of the memory. For example, if the narrowest data width is 8, and the depth of memory is 8 locations, then the parameter value should be passed as shown below. parameter MEMORY_INIT_PARAM = "AB,CD,EF,1,2,34,56,78" Where "AB" is the 0th location and "78" is the 7th location.
MEMORY_OPTIMIZATION	STRING	"true", "false"	"true"	Specify "true" to enable the optimization of unused memory or bits in the memory structure. Specify "false" to disable the optimization of unused memory or bits in the memory structure
MEMORY_SIZE	DECIMAL	2 to 150994944	2048	Specify the total memory array size, in bits. For example, enter 65536 for a 2kx32 RAM.
MESSAGE_CONTROL	DECIMAL	0 to 1	0	Specify 1 to enable the dynamic message reporting such as collision warnings, and 0 to disable the message reporting
READ_DATA_WIDTH_A	DECIMAL	1 to 4608	32	Specify the width of the port A read data output port douta, in bits. The values of READ_DATA_WIDTH_A and WRITE_DATA_WIDTH_A must be equal.
READ_DATA_WIDTH_B	DECIMAL	1 to 4608	32	Specify the width of the port B read data output port doutb, in bits. The values of READ_DATA_WIDTH_B and WRITE_DATA_WIDTH_B must be equal.
READ_LATENCY_A	DECIMAL	0 to 100	2	Specify the number of register stages in the port A read data pipeline. Read data output to port douta takes this number of clka cycles. To target block memory, a value of 1 or larger is required- 1 causes use of memory latch only; 2 causes use of output register. To target distributed memory, a value of 0 or larger is required- 0 indicates combinatorial output. Values larger than 2 synthesize additional flip-flops that are not retimed into memory primitives.
READ_LATENCY_B	DECIMAL	0 to 100	2	Specify the number of register stages in the port B read data pipeline. Read data output to port doutb takes this number of clkb cycles (clka when CLOCKING_MODE is "common_clock"). To target block memory, a value of 1 or larger is required- 1 causes use of memory latch only; 2 causes use of output register. To target distributed memory, a value of 0 or larger is required- 0 indicates combinatorial output. Values larger than 2 synthesize additional flip-flops that are not retimed into memory primitives.
READ_RESET_VALUE_A	STRING	String	"0"	Specify the reset value of the port A final output register stage in response to rsta input port is assertion. The value mentioned must be accomodated in READ_DATA_WIDTH_A number of bits.
READ_RESET_VALUE_B	STRING	String	"0"	Specify the reset value of the port B final output register stage in response to rstb input port is assertion. The value mentioned must be accomodated in READ_DATA_WIDTH_B number of bits.
RST_MODE_A	STRING	"SYNC", "ASYNC"	"SYNC"	Describes the behaviour of the reset "SYNC" - when reset is applied, synchronously resets output port douta to the value specified by parameter READ_RESET_VALUE_A "ASYNC" - when reset is applied, asynchronously resets output port douta to zero
RST_MODE_B	STRING	"SYNC", "ASYNC"	"SYNC"	Describes the behaviour of the reset "SYNC" - when reset is applied, synchronously resets output port doutb to the value specified by parameter READ_RESET_VALUE_B "ASYNC" - when reset is applied, asynchronously resets output port doutb to zero
SIM_ASSERT_CHK	DECIMAL	0 to 1	0	0- Disable simulation message reporting. Messages related to potential misuse will not be reported. 1- Enable simulation message reporting. Messages related to potential misuse will be reported.
USE_EMBEDDED_CONSTRAINT	DECIMAL	0 to 1	0	Specify 1 to enable the set_false_path constraint addition between clka of Distributed RAM and doutb_reg on clkb
USE_MEM_INIT	DECIMAL	0 to 1	1	Specify 1 to enable the generation of below message and 0 to disable generation of the following message completely. "INFO - MEMORY_INIT_FILE and MEMORY_INIT_PARAM together specifies no memory initialization. Initial memory contents will be all 0s." NOTE: This message gets generated only when there is no Memory Initialization specified either through file or Parameter.
USE_MEM_INIT_MMI	DECIMAL	0 to 1	0	Specify 1 to expose this memory information to be written out in the MMI file.
WRITE_DATA_WIDTH_A	DECIMAL	1 to 4608	32	Specify the width of the port A write data input port dina, in bits. The values of WRITE_DATA_WIDTH_A and READ_DATA_WIDTH_A must be equal.

VHDL Instantiation Template

Unless they already exist, copy the following two statements and paste them before the entity declaration.

Library xpm;
use xpm.vcomponents.all;


-- xpm_memory_dpdistram: Dual Port Distributed RAM
-- Xilinx Parameterized Macro, version 2022.2

xpm_memory_dpdistram_inst : xpm_memory_dpdistram
generic map (
   ADDR_WIDTH_A => 6,               -- DECIMAL
   ADDR_WIDTH_B => 6,               -- DECIMAL
   BYTE_WRITE_WIDTH_A => 32,        -- DECIMAL
   CLOCKING_MODE => "common_clock", -- String
   MEMORY_INIT_FILE => "none",      -- String
   MEMORY_INIT_PARAM => "0",        -- String
   MEMORY_OPTIMIZATION => "true",   -- String
   MEMORY_SIZE => 2048,             -- DECIMAL
   MESSAGE_CONTROL => 0,            -- DECIMAL
   READ_DATA_WIDTH_A => 32,         -- DECIMAL
   READ_DATA_WIDTH_B => 32,         -- DECIMAL
   READ_LATENCY_A => 2,             -- DECIMAL
   READ_LATENCY_B => 2,             -- DECIMAL
   READ_RESET_VALUE_A => "0",       -- String
   READ_RESET_VALUE_B => "0",       -- String
   RST_MODE_A => "SYNC",            -- String
   RST_MODE_B => "SYNC",            -- String
   SIM_ASSERT_CHK => 0,             -- DECIMAL; 0=disable simulation messages, 1=enable simulation messages
   USE_EMBEDDED_CONSTRAINT => 0,    -- DECIMAL
   USE_MEM_INIT => 1,               -- DECIMAL
   USE_MEM_INIT_MMI => 0,           -- DECIMAL
   WRITE_DATA_WIDTH_A => 32         -- DECIMAL
)
port map (
   douta => douta,   -- READ_DATA_WIDTH_A-bit output: Data output for port A read operations.
   doutb => doutb,   -- READ_DATA_WIDTH_B-bit output: Data output for port B read operations.
   addra => addra,   -- ADDR_WIDTH_A-bit input: Address for port A write and read operations.
   addrb => addrb,   -- ADDR_WIDTH_B-bit input: Address for port B write and read operations.
   clka => clka,     -- 1-bit input: Clock signal for port A. Also clocks port B when parameter
                     -- CLOCKING_MODE is "common_clock".

   clkb => clkb,     -- 1-bit input: Clock signal for port B when parameter CLOCKING_MODE is
                     -- "independent_clock". Unused when parameter CLOCKING_MODE is "common_clock".

   dina => dina,     -- WRITE_DATA_WIDTH_A-bit input: Data input for port A write operations.
   ena => ena,       -- 1-bit input: Memory enable signal for port A. Must be high on clock cycles when read
                     -- or write operations are initiated. Pipelined internally.

   enb => enb,       -- 1-bit input: Memory enable signal for port B. Must be high on clock cycles when read
                     -- or write operations are initiated. Pipelined internally.

   regcea => regcea, -- 1-bit input: Clock Enable for the last register stage on the output data path.
   regceb => regceb, -- 1-bit input: Do not change from the provided value.
   rsta => rsta,     -- 1-bit input: Reset signal for the final port A output register stage. Synchronously
                     -- resets output port douta to the value specified by parameter READ_RESET_VALUE_A.

   rstb => rstb,     -- 1-bit input: Reset signal for the final port B output register stage. Synchronously
                     -- resets output port doutb to the value specified by parameter READ_RESET_VALUE_B.

   wea => wea        -- WRITE_DATA_WIDTH_A/BYTE_WRITE_WIDTH_A-bit input: Write enable vector for port A
                     -- input data port dina. 1 bit wide when word-wide writes are used. In byte-wide write
                     -- configurations, each bit controls the writing one byte of dina to address addra. For
                     -- example, to synchronously write only bits [15-8] of dina when WRITE_DATA_WIDTH_A is
                     -- 32, wea would be 4'b0010.

);

-- End of xpm_memory_dpdistram_inst instantiation

Verilog Instantiation Template


// xpm_memory_dpdistram: Dual Port Distributed RAM
// Xilinx Parameterized Macro, version 2022.2

xpm_memory_dpdistram #(
   .ADDR_WIDTH_A(6),               // DECIMAL
   .ADDR_WIDTH_B(6),               // DECIMAL
   .BYTE_WRITE_WIDTH_A(32),        // DECIMAL
   .CLOCKING_MODE("common_clock"), // String
   .MEMORY_INIT_FILE("none"),      // String
   .MEMORY_INIT_PARAM("0"),        // String
   .MEMORY_OPTIMIZATION("true"),   // String
   .MEMORY_SIZE(2048),             // DECIMAL
   .MESSAGE_CONTROL(0),            // DECIMAL
   .READ_DATA_WIDTH_A(32),         // DECIMAL
   .READ_DATA_WIDTH_B(32),         // DECIMAL
   .READ_LATENCY_A(2),             // DECIMAL
   .READ_LATENCY_B(2),             // DECIMAL
   .READ_RESET_VALUE_A("0"),       // String
   .READ_RESET_VALUE_B("0"),       // String
   .RST_MODE_A("SYNC"),            // String
   .RST_MODE_B("SYNC"),            // String
   .SIM_ASSERT_CHK(0),             // DECIMAL; 0=disable simulation messages, 1=enable simulation messages
   .USE_EMBEDDED_CONSTRAINT(0),    // DECIMAL
   .USE_MEM_INIT(1),               // DECIMAL
   .USE_MEM_INIT_MMI(0),           // DECIMAL
   .WRITE_DATA_WIDTH_A(32)         // DECIMAL
)
xpm_memory_dpdistram_inst (
   .douta(douta),   // READ_DATA_WIDTH_A-bit output: Data output for port A read operations.
   .doutb(doutb),   // READ_DATA_WIDTH_B-bit output: Data output for port B read operations.
   .addra(addra),   // ADDR_WIDTH_A-bit input: Address for port A write and read operations.
   .addrb(addrb),   // ADDR_WIDTH_B-bit input: Address for port B write and read operations.
   .clka(clka),     // 1-bit input: Clock signal for port A. Also clocks port B when parameter CLOCKING_MODE
                    // is "common_clock".

   .clkb(clkb),     // 1-bit input: Clock signal for port B when parameter CLOCKING_MODE is
                    // "independent_clock". Unused when parameter CLOCKING_MODE is "common_clock".

   .dina(dina),     // WRITE_DATA_WIDTH_A-bit input: Data input for port A write operations.
   .ena(ena),       // 1-bit input: Memory enable signal for port A. Must be high on clock cycles when read
                    // or write operations are initiated. Pipelined internally.

   .enb(enb),       // 1-bit input: Memory enable signal for port B. Must be high on clock cycles when read
                    // or write operations are initiated. Pipelined internally.

   .regcea(regcea), // 1-bit input: Clock Enable for the last register stage on the output data path.
   .regceb(regceb), // 1-bit input: Do not change from the provided value.
   .rsta(rsta),     // 1-bit input: Reset signal for the final port A output register stage. Synchronously
                    // resets output port douta to the value specified by parameter READ_RESET_VALUE_A.

   .rstb(rstb),     // 1-bit input: Reset signal for the final port B output register stage. Synchronously
                    // resets output port doutb to the value specified by parameter READ_RESET_VALUE_B.

   .wea(wea)        // WRITE_DATA_WIDTH_A/BYTE_WRITE_WIDTH_A-bit input: Write enable vector for port A input
                    // data port dina. 1 bit wide when word-wide writes are used. In byte-wide write
                    // configurations, each bit controls the writing one byte of dina to address addra. For
                    // example, to synchronously write only bits [15-8] of dina when WRITE_DATA_WIDTH_A is
                    // 32, wea would be 4'b0010.

);

// End of xpm_memory_dpdistram_inst instantiation