XPM_FIFO_AXIL - 2025.2 English - Parameterized Macro: AXI Memory Mapped (AXI Lite) FIFO - UG1485

Versal Architecture Premium Series Libraries Guide (UG1485)
Document ID
UG1485
Release Date
2025-12-17
Version
2025.2 English

Parameterized Macro: AXI Memory Mapped (AXI Lite) FIFO

  • MACRO_GROUP: XPM
  • MACRO_SUBGROUP: XPM_FIFO

Introduction

This macro is used to instantiate AXI Memory Mapped (AXI Lite) FIFO.

AXI4 FIFO is derived from the XPM_FIFO_SYNC and XPM_FIFO_ASYNC. The AXI interface protocol uses a two-way valid and ready handshake mechanism. The information source uses the valid signal to show when valid data or control information is available on the channel. The information destination uses the ready signal to show when it can accept the data.

Timing Diagrams

Figure 1. Timing for Read and Write Operations to the AXI Stream FIFO

In the timing diagram above, the information source generates the valid signal to indicate when the data is available. The destination generates the ready signal to indicate that it can accept the data, and transfer occurs only when both the valid and ready signals are High.

Because AXI4 FIFO is derived from XPM_FIFO_SYNC and XPM_FIFO_ASYNC, much of the behavior is common between them. The ready signal is generated based on availability of space in the FIFO and is held high to allow writes to the FIFO. The ready signal is pulled Low only when there is no space in the FIFO left to perform additional writes. The valid signal is generated based on availability of data in the FIFO and is held High to allow reads to be performed from the FIFO. The valid signal is pulled Low only when there is no data available to be read from the FIFO. The information signals are mapped to the din and dout bus of XPM_FIFO_SYNC and XPM_FIFO_ASYNC. The width of the AXI4-Full FIFO is determined by concatenating all of the information signals of the AXI interface. The information signals include all AXI signals except for the valid and ready handshake signals.

AXI4 FIFO operates only in First-Word Fall-Through mode. The First-Word Fall-Through (FWFT) feature provides the ability to look ahead to the next word available from the FIFO without issuing a read operation. When data is available in the FIFO, the first word falls through the FIFO and appears automatically on the output data bus.

Port Descriptions

Port Direction Width Domain Sense Handling if Unused Function
dbiterr_rdch Output 1 m_aclk LEVEL_HIGH DoNotCare Double Bit Error- Indicates that the ECC decoder detected a double-bit error and data in the FIFO core is corrupted.
dbiterr_wdch Output 1 m_aclk LEVEL_HIGH DoNotCare Double Bit Error- Indicates that the ECC decoder detected a double-bit error and data in the FIFO core is corrupted.
injectdbiterr_rdch Input 1 s_aclk LEVEL_HIGH 0 Double Bit Error Injection- Injects a double bit error if the ECC feature is used.
injectdbiterr_wdch Input 1 s_aclk LEVEL_HIGH 0 Double Bit Error Injection- Injects a double bit error if the ECC feature is used.
injectsbiterr_rdch Input 1 s_aclk LEVEL_HIGH 0 Single Bit Error Injection- Injects a single bit error if the ECC feature is used.
injectsbiterr_wdch Input 1 s_aclk LEVEL_HIGH 0 Single Bit Error Injection- Injects a single bit error if the ECC feature is used.
m_aclk Input 1 NA EDGE_RISING Active Master Interface Clock: All signals on master interface are sampled on the rising edge of this clock.
m_axi_araddr Output AXI_ADDR_WIDTH m_aclk NA Active ARADDR: The read address bus gives the initial address of a read burst transaction. Only the start address of the burst is provided and the control signals that are issued alongside the address detail how the address is calculated for the remaining transfers in the burst.
m_axi_arprot Output 1 m_aclk NA Active ARPROT: Indicates the normal, privileged, or secure protection level of the transaction and whether the transaction is a data access or an instruction access.
m_axi_arready Input 1 m_aclk LEVEL_HIGH Active ARREADY: Indicates that the master can accept a transfer in the current cycle.
m_axi_arvalid Output 1 m_aclk LEVEL_HIGH Active ARVALID: Indicates that the master is driving a valid transfer.
  • A transfer takes place when both ARVALID and ARREADY are asserted
m_axi_awaddr Output AXI_ADDR_WIDTH m_aclk NA Active AWADDR: The write address bus gives the address of the first transfer in a write burst transaction. The associated control signals are used to determine the addresses of the remaining transfers in the burst.
m_axi_awprot Output 1 m_aclk NA Active AWPROT: Indicates the normal, privileged, or secure protection level of the transaction and whether the transaction is a data access or an instruction access.
m_axi_awready Input 1 m_aclk LEVEL_HIGH Active AWREADY: Indicates that the master can accept a transfer in the current cycle.
m_axi_awvalid Output 1 m_aclk LEVEL_HIGH Active AWVALID: Indicates that the master is driving a valid transfer.
  • A transfer takes place when both AWVALID and AWREADY are asserted
m_axi_bready Output 1 m_aclk LEVEL_HIGH Active BREADY: Indicates that the master can accept a transfer in the current cycle.
m_axi_bresp Input 1 m_aclk NA Active BRESP: Write Response. Indicates the status of the write transaction. The allowable responses are OKAY, EXOKAY, SLVERR, and DECERR.
m_axi_bvalid Input 1 m_aclk LEVEL_HIGH Active BVALID: Indicates that the master is driving a valid transfer.
  • A transfer takes place when both BVALID and BREADY are asserted
m_axi_rdata Input AXI_DATA_WIDTH m_aclk NA Active RDATA: The primary payload that is used to provide the data that is passing across the interface. The width of the data payload is an integer number of bytes.
m_axi_rready Output 1 m_aclk LEVEL_HIGH Active RREADY: Indicates that the master can accept a transfer in the current cycle.
m_axi_rresp Input 1 m_aclk NA Active RRESP: Indicates the status of the read transfer. The allowable responses are OKAY, EXOKAY, SLVERR, and DECERR.
m_axi_rvalid Input 1 m_aclk LEVEL_HIGH Active RVALID: Indicates that the master is driving a valid transfer.
  • A transfer takes place when both RVALID and RREADY are asserted
m_axi_wdata Output AXI_DATA_WIDTH m_aclk NA Active WDATA: The primary payload that is used to provide the data that is passing across the interface. The width of the data payload is an integer number of bytes.
m_axi_wready Input 1 m_aclk LEVEL_HIGH Active WREADY: Indicates that the master can accept a transfer in the current cycle.
m_axi_wstrb Output AXI_DATA_WIDTH / 8 m_aclk NA Active WSTRB: The byte qualifier that indicates whether the content of the associated byte of TDATA is processed as a data byte or a position byte. For a 64-bit DATA, bit 0 corresponds to the least significant byte on DATA, and bit 0 corresponds to the least significant byte on DATA, and bit 7 corresponds to the most significant byte. For example:
  • STROBE[0] = 1b, DATA[7:0] is valid
  • STROBE[7] = 0b, DATA[63:56] is not valid
m_axi_wvalid Output 1 m_aclk LEVEL_HIGH Active WVALID: Indicates that the master is driving a valid transfer.
  • A transfer takes place when both WVALID and WREADY are asserted
prog_empty_rdch Output 1 m_aclk LEVEL_HIGH DoNotCare

Programmable Empty- This signal is asserted when the number of words in the Read Data Channel FIFO is less than or equal to the programmable empty threshold value.

It is de-asserted when the number of words in the Read Data Channel FIFO exceeds the programmable empty threshold value.
prog_empty_wdch Output 1 m_aclk LEVEL_HIGH DoNotCare

Programmable Empty- This signal is asserted when the number of words in the Write Data Channel FIFO is less than or equal to the programmable empty threshold value.

It is de-asserted when the number of words in the Write Data Channel FIFO exceeds the programmable empty threshold value.
prog_full_rdch Output 1 s_aclk LEVEL_HIGH DoNotCare

Programmable Full: This signal is asserted when the number of words in the Read Data Channel FIFO is greater than or equal to the programmable full threshold value.

It is de-asserted when the number of words in the Read Data Channel FIFO is less than the programmable full threshold value.
prog_full_wdch Output 1 s_aclk LEVEL_HIGH DoNotCare

Programmable Full: This signal is asserted when the number of words in the Write Data Channel FIFO is greater than or equal to the programmable full threshold value.

It is de-asserted when the number of words in the Write Data Channel FIFO is less than the programmable full threshold value.
rd_data_count_rdch Output RD_DATA_COUNT_WIDTH_RDCH m_aclk NA DoNotCare Read Data Count- This bus indicates the number of words available for reading in the Read Data Channel FIFO.
rd_data_count_wdch Output RD_DATA_COUNT_WIDTH_WDCH m_aclk NA DoNotCare Read Data Count- This bus indicates the number of words available for reading in the Write Data Channel FIFO.
s_aclk Input 1 NA EDGE_RISING Active Slave Interface Clock: All signals on slave interface are sampled on the rising edge of this clock.
s_aresetn Input 1 NA LEVEL_LOW Active Active low asynchronous reset.
s_axi_araddr Input AXI_ADDR_WIDTH s_aclk NA Active ARADDR: The read address bus gives the initial address of a read burst transaction. Only the start address of the burst is provided and the control signals that are issued alongside the address detail how the address is calculated for the remaining transfers in the burst.
s_axi_arprot Input 1 s_aclk NA Active ARPROT: Indicates the normal, privileged, or secure protection level of the transaction and whether the transaction is a data access or an instruction access.
s_axi_arready Output 1 s_aclk LEVEL_HIGH Active ARREADY: Indicates that the slave can accept a transfer in the current cycle.
s_axi_arvalid Input 1 s_aclk LEVEL_HIGH Active ARVALID: Indicates that the master is driving a valid transfer.
  • A transfer takes place when both ARVALID and ARREADY are asserted
s_axi_awaddr Input AXI_ADDR_WIDTH s_aclk NA Active AWADDR: The write address bus gives the address of the first transfer in a write burst transaction. The associated control signals are used to determine the addresses of the remaining transfers in the burst.
s_axi_awprot Input 1 s_aclk LEVEL_HIGH Active AWPROT: Indicates the normal, privileged, or secure protection level of the transaction and whether the transaction is a data access or an instruction access.
s_axi_awready Output 1 s_aclk LEVEL_HIGH Active AWREADY: Indicates that the slave can accept a transfer in the current cycle.
s_axi_awvalid Input 1 s_aclk LEVEL_HIGH Active AWVALID: Indicates that the master is driving a valid transfer.
  • A transfer takes place when both AWVALID and AWREADY are asserted
s_axi_bready Input 1 s_aclk LEVEL_HIGH Active BREADY: Indicates that the slave can accept a transfer in the current cycle.
s_axi_bresp Output 1 s_aclk NA Active BRESP: Write Response. Indicates the status of the write transaction. The allowable responses are OKAY, EXOKAY, SLVERR, and DECERR.
s_axi_bvalid Output 1 s_aclk LEVEL_HIGH Active BVALID: Indicates that the master is driving a valid transfer.
  • A transfer takes place when both BVALID and BREADY are asserted
s_axi_rdata Output AXI_DATA_WIDTH s_aclk NA Active RDATA: The primary payload that is used to provide the data that is passing across the interface. The width of the data payload is an integer number of bytes.
s_axi_rready Input 1 s_aclk LEVEL_HIGH Active RREADY: Indicates that the slave can accept a transfer in the current cycle.
s_axi_rresp Output 1 s_aclk NA Active RRESP: Indicates the status of the read transfer. The allowable responses are OKAY, EXOKAY, SLVERR, and DECERR.
s_axi_rvalid Output 1 s_aclk LEVEL_HIGH Active RVALID: Indicates that the master is driving a valid transfer.
  • A transfer takes place when both RVALID and RREADY are asserted
s_axi_wdata Input AXI_DATA_WIDTH s_aclk NA Active WDATA: The primary payload that is used to provide the data that is passing across the interface. The width of the data payload is an integer number of bytes.
s_axi_wready Output 1 s_aclk LEVEL_HIGH Active WREADY: Indicates that the slave can accept a transfer in the current cycle.
s_axi_wstrb Input AXI_DATA_WIDTH / 8 s_aclk NA Active WSTRB: The byte qualifier that indicates whether the content of the associated byte of TDATA is processed as a data byte or a position byte. For a 64-bit DATA, bit 0 corresponds to the least significant byte on DATA, and bit 0 corresponds to the least significant byte on DATA, and bit 7 corresponds to the most significant byte. For example:
  • STROBE[0] = 1b, DATA[7:0] is valid
  • STROBE[7] = 0b, DATA[63:56] is not valid
s_axi_wvalid Input 1 s_aclk LEVEL_HIGH Active WVALID: Indicates that the master is driving a valid transfer.
  • A transfer takes place when both WVALID and WREADY are asserted
sbiterr_rdch Output 1 m_aclk LEVEL_HIGH DoNotCare Single Bit Error- Indicates that the ECC decoder detected and fixed a single-bit error.
sbiterr_wdch Output 1 m_aclk LEVEL_HIGH DoNotCare Single Bit Error- Indicates that the ECC decoder detected and fixed a single-bit error.
wr_data_count_rdch Output WR_DATA_COUNT_WIDTH_RDCH s_aclk NA DoNotCare Write Data Count: This bus indicates the number of words written into the Read Data Channel FIFO.
wr_data_count_wdch Output WR_DATA_COUNT_WIDTH_WDCH s_aclk NA DoNotCare Write Data Count: This bus indicates the number of words written into the Write Data Channel FIFO.

Design Entry Method

Instantiation Yes
Inference No
IP and IP Integrator Catalog No

Available Attributes

Attribute Type Allowed Values Default Description
AXI_ADDR_WIDTH DECIMAL 1 to 64 32 Defines the width of the ADDR ports, s_axi_araddr, s_axi_awaddr, m_axi_araddr and m_axi_awaddr
AXI_DATA_WIDTH DECIMAL 8 to 1024 32 Defines the width of the DATA ports, s_axi_rdata, s_axi_wdata, m_axi_rdata and m_axi_wdata NOTE: The maximum FIFO size (width x depth) is limited to 150-Megabits.
CASCADE_HEIGHT DECIMAL 0 to 64 0

0- No Cascade Height, Allow Vivado Synthesis to choose.

1 or more - Vivado Synthesis sets the specified value as Cascade Height.
CDC_SYNC_STAGES DECIMAL 2 to 8 2

Specifies the number of synchronization stages on the CDC path.

Applicable only if CLOCKING_MODE = "independent_clock"
CLOCKING_MODE STRING "common_clock", "independent_clock" "common_clock" Designate whether AXI Memory Mapped FIFO is clocked with a common clock or with independent clocks-
  • "common_clock"- Common clocking; clock both write and read domain s_aclk
  • "independent_clock"- Independent clocking; clock write domain with s_aclk and read domain with m_aclk
ECC_MODE_RDCH STRING "no_ecc", "en_ecc" "no_ecc"
  • "no_ecc" - Disables ECC
  • "en_ecc" - Enables both ECC Encoder and Decoder
ECC_MODE_WDCH STRING "no_ecc", "en_ecc" "no_ecc"
  • "no_ecc" - Disables ECC
  • "en_ecc" - Enables both ECC Encoder and Decoder
EN_RESET_SYNCHRONIZER DECIMAL 0 to 1 1

0- Disable synchronizing stages in the reset path.

1- Enable synchronizing stages in the reset path. Based on CLOCKING_MODE number of synchronizing stages will differ
EN_SIM_ASSERT_ERR STRING String "warning"
  • "warning" - Report warning message for FIFO overflow and underflow in simulation.
  • "error" - Report error message for FIFO overflow and underflow in simulation.
  • "fatal" - Report fatal message for FIFO overflow and underflow in simulation.
FIFO_DEPTH_RACH DECIMAL 16 to 4194304 2048 Defines the AXI Memory Mapped FIFO Write Depth, must be power of two NOTE: The maximum FIFO size (width x depth) is limited to 150-Megabits.
FIFO_DEPTH_RDCH DECIMAL 16 to 4194304 2048 Defines the AXI Memory Mapped FIFO Write Depth, must be power of two NOTE: The maximum FIFO size (width x depth) is limited to 150-Megabits.
FIFO_DEPTH_WACH DECIMAL 16 to 4194304 2048 Defines the AXI Memory Mapped FIFO Write Depth, must be power of two NOTE: The maximum FIFO size (width x depth) is limited to 150-Megabits.
FIFO_DEPTH_WDCH DECIMAL 16 to 4194304 2048 Defines the AXI Memory Mapped FIFO Write Depth, must be power of two NOTE: The maximum FIFO size (width x depth) is limited to 150-Megabits.
FIFO_DEPTH_WRCH DECIMAL 16 to 4194304 2048 Defines the AXI Memory Mapped FIFO Write Depth, must be power of two NOTE: The maximum FIFO size (width x depth) is limited to 150-Megabits.
FIFO_MEMORY_TYPE_RACH STRING "auto", "block", "distributed", "ultra" "auto" Designate the fifo memory primitive (resource type) to use-
  • "auto"- Allow Vivado Synthesis to choose
  • "block"- Block RAM FIFO
  • "distributed"- Distributed RAM FIFO
  • "ultra"- URAM FIFO
NOTE: There may be a behavior mismatch if Block RAM or Ultra RAM specific features, like ECC or Asymmetry, are selected with FIFO_MEMORY_TYPE_RACH set to "auto".
FIFO_MEMORY_TYPE_RDCH STRING "auto", "block", "distributed", "ultra" "auto" Designate the fifo memory primitive (resource type) to use-
  • "auto"- Allow Vivado Synthesis to choose
  • "block"- Block RAM FIFO
  • "distributed"- Distributed RAM FIFO
  • "ultra"- URAM FIFO
NOTE: There may be a behavior mismatch if Block RAM or Ultra RAM specific features, like ECC or Asymmetry, are selected with FIFO_MEMORY_TYPE_RDCH set to "auto".
FIFO_MEMORY_TYPE_WACH STRING "auto", "block", "distributed", "ultra" "auto" Designate the fifo memory primitive (resource type) to use-
  • "auto"- Allow Vivado Synthesis to choose
  • "block"- Block RAM FIFO
  • "distributed"- Distributed RAM FIFO
  • "ultra"- URAM FIFO
NOTE: There may be a behavior mismatch if Block RAM or Ultra RAM specific features, like ECC or Asymmetry, are selected with FIFO_MEMORY_TYPE_WACH set to "auto".
FIFO_MEMORY_TYPE_WDCH STRING "auto", "block", "distributed", "ultra" "auto" Designate the fifo memory primitive (resource type) to use-
  • "auto"- Allow Vivado Synthesis to choose
  • "block"- Block RAM FIFO
  • "distributed"- Distributed RAM FIFO
  • "ultra"- URAM FIFO
NOTE: There may be a behavior mismatch if Block RAM or Ultra RAM specific features, like ECC or Asymmetry, are selected with FIFO_MEMORY_TYPE_WDCH set to "auto".
FIFO_MEMORY_TYPE_WRCH STRING "auto", "block", "distributed", "ultra" "auto" Designate the fifo memory primitive (resource type) to use-
  • "auto"- Allow Vivado Synthesis to choose
  • "block"- Block RAM FIFO
  • "distributed"- Distributed RAM FIFO
  • "ultra"- URAM FIFO
NOTE: There may be a behavior mismatch if Block RAM or Ultra RAM specific features, like ECC or Asymmetry, are selected with FIFO_MEMORY_TYPE_WRCH set to "auto".
PROG_EMPTY_THRESH_RDCH DECIMAL 5 to 4194301 10

Specifies the minimum number of read words in the FIFO at or below which prog_empty is asserted.

  • Min_Value = 5
  • Max_Value = FIFO_WRITE_DEPTH - 5
NOTE: The default threshold value is dependent on default FIFO_WRITE_DEPTH value. If FIFO_WRITE_DEPTH value is changed, ensure the threshold value is within the valid range though the programmable flags are not used.
PROG_EMPTY_THRESH_WDCH DECIMAL 5 to 4194301 10

Specifies the minimum number of read words in the FIFO at or below which prog_empty is asserted.

  • Min_Value = 5
  • Max_Value = FIFO_WRITE_DEPTH - 5
NOTE: The default threshold value is dependent on default FIFO_WRITE_DEPTH value. If FIFO_WRITE_DEPTH value is changed, ensure the threshold value is within the valid range though the programmable flags are not used.
PROG_FULL_THRESH_RDCH DECIMAL 5 to 4194301 10

Specifies the maximum number of write words in the FIFO at or above which prog_full is asserted.

  • Min_Value = 5 + CDC_SYNC_STAGES
  • Max_Value = FIFO_WRITE_DEPTH - 5
NOTE: The default threshold value is dependent on default FIFO_WRITE_DEPTH value. If FIFO_WRITE_DEPTH value is changed, ensure the threshold value is within the valid range though the programmable flags are not used.
PROG_FULL_THRESH_WDCH DECIMAL 5 to 4194301 10

Specifies the maximum number of write words in the FIFO at or above which prog_full is asserted.

  • Min_Value = 5 + CDC_SYNC_STAGES
  • Max_Value = FIFO_WRITE_DEPTH - 5
NOTE: The default threshold value is dependent on default FIFO_WRITE_DEPTH value. If FIFO_WRITE_DEPTH value is changed, ensure the threshold value is within the valid range though the programmable flags are not used.
RD_DATA_COUNT_WIDTH_RDCH DECIMAL 1 to 23 1 Specifies the width of rd_data_count_rdch. To reflect the correct value, the width should be log2(FIFO_DEPTH)+1.
RD_DATA_COUNT_WIDTH_WDCH DECIMAL 1 to 23 1 Specifies the width of rd_data_count_wdch. To reflect the correct value, the width should be log2(FIFO_DEPTH)+1.
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_ADV_FEATURES_RDCH STRING String "1000"

Enables rd_data_count_rdch, prog_empty_rdch, wr_data_count_rdch, prog_full_rdch sideband signals.

  • Setting USE_ADV_FEATURES_RDCH[1] to 1 enables prog_full_rdch flag; Default value of this bit is 0
  • Setting USE_ADV_FEATURES_RDCH[2] to 1 enables wr_data_count_rdch; Default value of this bit is 0
  • Setting USE_ADV_FEATURES_RDCH[9] to 1 enables prog_empty_rdch flag; Default value of this bit is 0
  • Setting USE_ADV_FEATURES_RDCH[10] to 1 enables rd_data_count_rdch; Default value of this bit is 0
USE_ADV_FEATURES_WDCH STRING String "1000"

Enables rd_data_count_wdch, prog_empty_wdch, wr_data_count_wdch, prog_full_wdch sideband signals.

  • Setting USE_ADV_FEATURES_WDCH[1] to 1 enables prog_full_wdch flag; Default value of this bit is 0
  • Setting USE_ADV_FEATURES_WDCH[2] to 1 enables wr_data_count_wdch; Default value of this bit is 0
  • Setting USE_ADV_FEATURES_WDCH[9] to 1 enables prog_empty_wdch flag; Default value of this bit is 0
  • Setting USE_ADV_FEATURES_WDCH[10] to 1 enables rd_data_count_wdch; Default value of this bit is 0
WR_DATA_COUNT_WIDTH_RDCH DECIMAL 1 to 23 1 Specifies the width of wr_data_count_rdch. To reflect the correct value, the width should be log2(FIFO_DEPTH)+1.
WR_DATA_COUNT_WIDTH_WDCH DECIMAL 1 to 23 1 Specifies the width of wr_data_count_wdch. To reflect the correct value, the width should be log2(FIFO_DEPTH)+1.

VHDL Instantiation Template

Verilog Instantiation Template

Related Information