Bitvis VIP AXI4-Lite

Quick Access

• BFM

  • axilite_write()

  • axilite_read()

  • axilite_check()

  • init_axilite_if_signals()

• VVC

  • axilite_write()

  • axilite_read()

  • axilite_check()

---

BFM

BFM functionality is implemented in axilite_bfm_pkg.vhd

Signal Record

t_axilite_if

Record element	Type
write_address_channel	t_axilite_write_address_channel
write_data_channel	t_axilite_write_data_channel
write_response_channel	t_axilite_write_response_channel
read_address_channel	t_axilite_read_address_channel
read_data_channel	t_axilite_read_data_channel

Note

• For more information on the AXI4-Lite signals, refer to “AMBA® AXI™ and ACE™ Protocol Specification”, Part B (ARM IHI 0022G), available from ARM.

Configuration Record

t_axilite_bfm_config

Default value for the record is C_AXILITE_BFM_CONFIG_DEFAULT.

Record element	Type	Default	Description
max_wait_cycles	natural	10	The maximum number of clock cycles to wait for the DUT ready or valid signals before reporting a timeout alert
max_wait_cycles_severity	t_alert_level	TB_FAILURE	The above timeout will have this severity
clock_period	time	-1 ns	Period of the clock signal
clock_period_margin	time	0 ns	Input clock period margin to specified clock_period. Will check ‘T/2’ if input clock is low when BFM is called and ‘T’ if input clock is high.
clock_margin_severity	t_alert_level	TB_ERROR	The above margin will have this severity
setup_time	time	-1 ns	Generated signals setup time. Suggested value is clock_period/4. An alert is reported if setup_time exceeds clock_period/2.
hold_time	time	-1 ns	Generated signals hold time. Suggested value is clock_period/4. An alert is reported if hold_time exceeds clock_period/2.
bfm_sync	t_bfm_sync	SYNC_ON_CLOCK_ONLY	When set to SYNC_ON_CLOCK_ONLY the BFM will enter on the first falling edge, estimate the clock period, synchronize the output signals and exit ¼ clock period after a succeeding rising edge. When set to SYNC_WITH_SETUP_AND_HOLD the BFM will use the configured setup_time, hold_time and clock_period to synchronize output signals with clock edges.
match_strictness	t_match_strictness	MATCH_EXACT	Matching strictness for std_logic values in check procedures. MATCH_EXACT requires both values to be the same. Note that the expected value can contain the don’t care operator ‘-‘. MATCH_STD allows comparisons between ‘H’ and ‘1’, ‘L’ and ‘0’ and ‘-’ in both values.
expected_response	t_xresp	OKAY	Sets the expected response for both read and write transactions
expected_response_severity	t_alert_level	TB_FAILURE	A response mismatch will have this severity
protection_setting	t_axprot	UNPRIVILEGED_NONSECURE_DATA	Sets the access permissions (e.g. write to data/instruction, privileged and secure access)
num_aw_pipe_stages	natural	1	Write Address Channel pipeline steps
num_w_pipe_stages	natural	1	Write Data Channel pipeline steps
num_ar_pipe_stages	natural	1	Read Address Channel pipeline steps
num_r_pipe_stages	natural	1	Read Data Channel pipeline steps
num_b_pipe_stages	natural	1	Response Channel pipeline steps
id_for_bfm	t_msg_id	ID_BFM	Message ID used for logging general messages in the BFM
id_for_bfm_wait	t_msg_id	ID_BFM_WAIT	Message ID used for logging waits in the BFM
id_for_bfm_poll	t_msg_id	ID_BFM_POLL	Message ID used for logging polling in the BFM

Methods

• All signals are active high.

• All parameters in brackets are optional.

Note

The AXI4-Lite BFM procedures do not access the AXI channels independently. However, this is sufficient for most use cases. If independent channel access is required, for instance simultaneous read and write accesses, use the VVC.

axilite_write()

Writes the given data to the given address of the DUT, using the AXI4-Lite protocol. For protocol details, see the AXI4-Lite specification. If the byte_enable argument is not used, it will be set to all ‘1’, i.e. all bytes are used.

The procedure reports an alert if:

• Data length is neither 32 bit nor 64 bit (alert level: TB_ERROR)

• wready does not occur within max_wait_cycles clock cycles (alert level: max_wait_cycles_severity, set in the config)

• awready does not occur within max_wait_cycles clock cycles (alert level: max_wait_cycles_severity, set in the config)

• bresp is not set to expected_response (set in the config) when bvalid is set to ‘1’ (alert level: expected_response_severity, set in the config)

• bvalid is not set within max_wait_cycles clock cycles (alert level: max_wait_cycles_severity, set in the config)

axilite_write(addr_value, data_value, [byte_enable,] msg, clk, axilite_if, [scope, [msg_id_panel, [config]]])

Object	Name	Dir.	Type	Description
constant	addr_value	in	unsigned	The address of an AXI4-Lite accessible register
constant	data_value	in	std_logic_vector	The data value to be written to the addressed register
constant	byte_enable	in	std_logic_vector	This argument selects which bytes to use (all ‘1’ means all bytes are updated)
constant	msg	in	string	A custom message to be appended in the log/alert
signal	clk	in	std_logic	The clock signal used to read and write data in/out of the AXI4-Lite BFM
signal	axilite_if	inout	t_axilite_if	AXI4-Lite signal interface record
constant	scope	in	string	Describes the scope from which the log/alert originates. Default value is C_BFM_SCOPE (“AXILITE_BFM”).
constant	msg_id_panel	in	t_msg_id_panel	Controls verbosity within a specified scope. Default value is shared_msg_id_panel.
constant	config	in	t_axilite_bfm_config	Configuration of BFM behavior and restrictions. Default value is C_AXILITE_BFM_CONFIG_DEFAULT.

-- Examples:
axilite_write(x"00101155", x"AAAA", "Writing data to Peripheral 1", clk, axilite_if, C_SCOPE, shared_msg_id_panel, C_AXILITE_BFM_CONFIG_DEFAULT);
axilite_write(C_ADDR_PERIPHERAL_1, x"00F1", "01", "Writing first byte to Peripheral 1", clk, axilite_if, C_SCOPE, shared_msg_id_panel, C_AXILITE_BFM_CONFIG_DEFAULT);

-- Suggested usage (requires local overload, see 'Local BFM overloads' section):
axilite_write(C_ADDR_DMA, x"AAAA", "Writing data to DMA");

axilite_read()

Reads data from the DUT at the given address, using the AXI4-Lite protocol. For protocol details, see the AXI4-Lite specification. The read data is placed on the output ‘data_value’ when the read has completed.

The procedure reports an alert if:

• The read data length (rdata) is neither 32 bit nor 64 bit (alert level: TB_ERROR)

• arready does not occur within max_wait_cycles clock cycles (alert level: max_wait_cycles_severity, set in the config)

• rresp is not set to expected_response (set in the config) when rvalid is set to ‘1’ (alert level: expected_response_severity, set in the config)

• rvalid is not set within max_wait_cycles clock cycles (alert level: max_wait_cycles_severity, set in the config)

axilite_read(addr_value, data_value, msg, clk, axilite_if, [scope, [msg_id_panel, [config]]])

Object	Name	Dir.	Type	Description
constant	addr_value	in	unsigned	The address of an AXI4-Lite accessible register
variable	data_value	out	std_logic_vector	The data value to be read from the addressed register
constant	msg	in	string	A custom message to be appended in the log/alert
signal	clk	in	std_logic	The clock signal used to read and write data in/out of the AXI4-Lite BFM
signal	axilite_if	inout	t_axilite_if	AXI4-Lite signal interface record
constant	scope	in	string	Describes the scope from which the log/alert originates. Default value is C_BFM_SCOPE (“AXILITE_BFM”).
constant	msg_id_panel	in	t_msg_id_panel	Controls verbosity within a specified scope. Default value is shared_msg_id_panel.
constant	config	in	t_axilite_bfm_config	Configuration of BFM behavior and restrictions. Default value is C_AXILITE_BFM_CONFIG_DEFAULT.

-- Examples:
axilite_read(C_ADDR_PERIPHERAL_1, v_data_out, "Read from Peripheral 1", clk, axilite_if, C_SCOPE, shared_msg_id_panel, C_AXILITE_BFM_CONFIG_DEFAULT);

-- Suggested usage (requires local overload, see 'Local BFM overloads' section):
axilite_read(C_ADDR_IO, v_data_out, "Reading from IO device");

axilite_check()

Reads data from the DUT at the given address, using the AXI4-Lite protocol. For protocol details, see the AXI4-Lite specification. After reading data from the AXI4-Lite bus, the read data is compared with the expected data, and if they don’t match, an alert with severity ‘alert_level’ is reported. The procedure also report alerts for the same conditions as the axilite_read() procedure.

axilite_check(addr_value, data_exp, msg, clk, axilite_if, [alert_level, [scope, [msg_id_panel, [config]]]])

Object	Name	Dir.	Type	Description
constant	addr_value	in	unsigned	The address of an AXI4-Lite accessible register
constant	data_exp	in	std_logic_vector	The data value to expect when reading the addressed register
constant	msg	in	string	A custom message to be appended in the log/alert
signal	clk	in	std_logic	The clock signal used to read and write data in/out of the AXI4-Lite BFM
signal	axilite_if	inout	t_axilite_if	AXI4-Lite signal interface record
constant	alert_level	in	t_alert_level	Sets the severity for the alert. Default value is ERROR.
constant	scope	in	string	Describes the scope from which the log/alert originates. Default value is C_BFM_SCOPE (“AXILITE_BFM”).
constant	msg_id_panel	in	t_msg_id_panel	Controls verbosity within a specified scope. Default value is shared_msg_id_panel.
constant	config	in	t_axilite_bfm_config	Configuration of BFM behavior and restrictions. Default value is C_AXILITE_BFM_CONFIG_DEFAULT.

-- Examples:
axilite_check(C_ADDR_PERIPHERAL_1, x"3B", "Check data from Peripheral 1", clk, axilite_if, C_SCOPE, shared_msg_id_panel, ERROR, C_AXILITE_BFM_CONFIG_DEFAULT);

-- Suggested usage (requires local overload, see 'Local BFM overloads' section):
axilite_check(C_ADDR_UART_RX, x"3B", "Checking data in UART RX register");

init_axilite_if_signals()

Initializes the AXI4-Lite interface. All the BFM outputs are set to ‘0’, and BFM inputs are set to ‘Z’. awprot and arprot are set to UNPRIVILEGED_NONSECURE_DATA (“010”).

t_axilite_if := init_axilite_if_signals(addr_width, data_width)

Object	Name	Dir.	Type	Description
constant	addr_width	in	natural	Width of the address signals
constant	data_width	in	natural	Width of the data signals

-- Examples:
axilite_if <= init_axilite_if_signals(addr_width, data_width)

Local types

t_axilite_write_address_channel

Record element	Type
awaddr	std_logic_vector
awvalid	std_logic
awprot	std_logic_vector(2 downto 0)
awready	std_logic

t_axilite_write_data_channel

Record element	Type
wdata	std_logic_vector
wstrb	std_logic_vector
wvalid	std_logic
wready	std_logic

t_axilite_write_response_channel

Record element	Type
bready	std_logic
bresp	std_logic_vector(1 downto 0)
bvalid	std_logic

t_axilite_read_address_channel

Record element	Type
araddr	std_logic_vector
arvalid	std_logic
arprot	std_logic_vector(2 downto 0)
arready	std_logic

t_axilite_read_data_channel

Record element	Type
rready	std_logic
rdata	std_logic_vector
rresp	std_logic_vector(1 downto 0)
rvalid	std_logic

t_axprot

UNPRIVILEGED_NONSECURE_DATA, UNPRIVILEGED_NONSECURE_INSTRUCTION, UNPRIVILEGED_SECURE_DATA, UNPRIVILEGED_SECURE_INSTRUCTION, PRIVILEGED_NONSECURE_DATA, PRIVILEGED_NONSECURE_INSTRUCTION, PRIVILEGED_SECURE_DATA, PRIVILEGED_SECURE_INSTRUCTION

t_xresp

OKAY, SLVERR, DECERR, ILLEGAL

Local BFM overloads

A good approach for better readability and maintainability is to make simple, local overloads for the BFM procedures in the TB process. This allows calling the BFM procedures with the key parameters only, e.g.

axilite_write(C_ADDR_PERIPHERAL_1, C_TEST_DATA, "Sending data to Peripheral 1");

rather than

axilite_write(C_ADDR_PERIPHERAL_1, C_TEST_DATA, "Sending data to Peripheral 1", clk, axilite_if, C_SCOPE, shared_msg_id_panel, C_AXILITE_BFM_CONFIG_DEFAULT);

By defining the local overload as e.g.

procedure axilite_write(
  constant addr_value   : in unsigned;
  constant data_value   : in std_logic_vector;
  constant msg          : in string
) is
begin
  axilite_write(
    addr_value,                  -- Keep as is
    data_value,                  -- Keep as is
    msg,                         -- Keep as is
    clk,                         -- Signal must be visible in local process scope
    axilite_if,                  -- Signal must be visible in local process scope
    C_SCOPE,                     -- Setting a default value
    shared_msg_id_panel,         -- Use global, shared msg_id_panel
    C_AXILITE_BFM_CONFIG_LOCAL); -- Use locally defined configuration or C_AXILITE_BFM_CONFIG_DEFAULT
end procedure;

Using a local overload like this also allows the following – if wanted:

• Have address value as natural – and convert in the overload

• Set up defaults for constants. May be different for two overloads of the same BFM

• Apply dedicated message ID panel to allow dedicated verbosity control

Compilation

• This BFM package may only be compiled with VHDL-2008 or newer. It is dependent on the Utility Library, which is only compatible with VHDL-2008 or newer.

• After UVVM-Util has been compiled, the BFM package can be compiled into any desired library.

• See Essential Mechanisms - Compile Scripts for information about compile scripts.

Simulator compatibility and setup

• See Prerequisites for a list of supported simulators.

• For required simulator setup see UVVM-Util Simulator compatibility and setup.

Additional Documentation

For more information on the AXI4-Lite specification, refer to “AMBA® AXI™ and ACE™ Protocol Specification”, Part B (ARM IHI 0022G), available from ARM.

Important

• This is a simplified Bus Functional Model (BFM) for AXI4-Lite.

• The given BFM complies with the basic AXI4-Lite protocol and thus allows a normal access towards an AXI4-Lite interface.

• This BFM is not an AXI4-Lite protocol checker.

• For a more advanced BFM please contact UVVM support at info@uvvm.org

---

VVC

• VVC functionality is implemented in axilite_vvc.vhd

• For general information see VVC Framework - Essential Mechanisms.

Entity

Generics

Name	Type	Default	Description
GC_ADDR_WIDTH	integer	8	Width of the AXI4-Lite address bus
GC_DATA_WIDTH	integer	32	Width of the AXI4-Lite data bus
GC_INSTANCE_IDX	natural	1	Instance number to assign the VVC
GC_AXILITE_CONFIG	t_axilite_bfm_config	C_AXILITE_BFM_CONFIG_DEFAULT	Configuration for the AXI4-Lite BFM
GC_CMD_QUEUE_COUNT_MAX	natural	C_CMD_QUEUE_COUNT_MAX	Absolute maximum number of commands in the VVC command queue
GC_CMD_QUEUE_COUNT_THRESHOLD	natural	C_CMD_QUEUE_COUNT_THRESHOLD	An alert will be generated when reaching this threshold to indicate that the command queue is almost full. The queue will still accept new commands until it reaches GC_CMD_QUEUE_COUNT_MAX.
GC_CMD_QUEUE_COUNT_THRESHOLD_SEVERITY	t_alert_level	C_CMD_QUEUE_COUNT_THRESHOLD_SEVERITY	Alert severity which will be used when command queue reaches GC_CMD_QUEUE_COUNT_THRESHOLD
GC_RESULT_QUEUE_COUNT_MAX	natural	C_RESULT_QUEUE_COUNT_MAX	Maximum number of unfetched results before result_queue is full
GC_RESULT_QUEUE_COUNT_THRESHOLD	natural	C_RESULT_QUEUE_COUNT_THRESHOLD	An alert will be issued if result queue exceeds this count. Used for early warning if result queue is almost full. Will be ignored if set to 0.
GC_RESULT_QUEUE_COUNT_THRESHOLD_SEVERITY	t_alert_level	C_RESULT_QUEUE _COUNT_THRESHOLD_SEVERITY	Severity of alert to be initiated if exceeding GC_RESULT_QUEUE_COUNT_THRESHOLD

Signals

Object	Name	Dir.	Type	Description
signal	clk	in	std_logic	VVC Clock signal
signal	axilite_vvc_master_if	inout	t_axilite_if	AXI4-Lite signal interface record

In this VVC, the interface has been encapsulated in a signal record of type t_axilite_if in order to improve readability of the code. Since the AXI4-Lite interface buses can be of arbitrary size, the interface vectors have been left unconstrained. These unconstrained vectors need to be constrained when the interface signals are instantiated. For this interface, it could look like:

signal axilite_if : t_axilite_if(write_address_channel(awaddr(C_ADDR_WIDTH    -1 downto 0)),
                                 write_data_channel   (wdata (C_DATA_WIDTH    -1 downto 0),
                                                       wstrb ((C_DATA_WIDTH/8)-1 downto 0)),
                                 read_address_channel (araddr(C_ADDR_WIDTH    -1 downto 0)),
                                 read_data_channel    (rdata (C_DATA_WIDTH    -1 downto 0)));

Configuration Record

vvc_config accessible via shared_axilite_vvc_config

Record element	Type	Default	Description
inter_bfm_delay	t_inter_bfm_delay	C_AXILITE_INTER_BFM_DELAY_DEFAULT	Delay between any requested BFM accesses towards the DUT. TIME_START2START: Time from a BFM start to the next BFM start (a TB_WARNING will be issued if access takes longer than TIME_START2START). TIME_FINISH2START: Time from a BFM end to the next BFM start. Any insert_delay() command will add to the above minimum delays, giving for instance the ability to skew the BFM starting time.
cmd_queue_count_max	natural	C_CMD_QUEUE_COUNT_MAX	Maximum pending number in command queue before queue is full. Adding additional commands will result in an ERROR.
cmd_queue_count_threshold	natural	C_CMD_QUEUE_COUNT_THRESHOLD	An alert will be issued if command queue exceeds this count. Used for early warning if command queue is almost full. Will be ignored if set to 0.
cmd_queue_count_threshold_severity	t_alert_level	C_CMD_QUEUE_COUNT_THRESHOLD_SEERITY	Severity of alert to be initiated if exceeding cmd_queue_count_threshold
result_queue_count_max	natural	C_RESULT_QUEUE_COUNT_MAX	Maximum number of unfetched results before result_queue is full
result_queue_count_threshold	natural	C_RESULT_QUEUE_COUNT_THRESHOLD	An alert will be issued if result queue exceeds this count. Used for early warning if result queue is almost full. Will be ignored if set to 0.
result_queue_count_threshold_severity	t_alert_level	C_RESULT_QUEUE_COUNT_THRESHOLD_SEVERITY	Severity of alert to be initiated if exceeding result_queue_count_threshold
bfm_config	t_axilite_bfm_config	C_AXILITE_BFM_CONFIG_DEFAULT	Configuration for the AXI4-Lite BFM
msg_id_panel	t_msg_id_panel	C_VVC_MSG_ID_PANEL_DEFAULT	VVC dedicated message ID panel. See Scope of Verbosity Control for how to use verbosity control.
force_single_pending_transac/ tion	boolean	false	Waits until the previous transaction is completed before starting the next one
unwanted_activity_severity	t_alert_level	C_UNWANTED_ACTIVITY_SEVERITY	Severity of alert to be issued if unwanted activity on the DUT outputs is detected. It is enabled with ERROR severity by default.

Note

cmd/result queue parameters in the configuration record are unused and will be removed in v3.0, use instead the entity generic constants.

The configuration record can be accessed from the Central Testbench Sequencer through the shared variable array, e.g.

shared_axilite_vvc_config(1).inter_bfm_delay.delay_in_time := 50 ns;
shared_axilite_vvc_config(1).bfm_config.clock_period := 10 ns;

Status Record

vvc_status accessible via shared_axilite_vvc_status

The current status of the VVC can be retrieved during simulation. This is achieved by reading from the shared variable from the test sequencer. The record contents can be seen below:

Record element	Type	Description
current_cmd_idx	natural	Command index currently running
previous_cmd_idx	natural	Previous command index to run
pending_cmd_idx	natural	Pending number of commands in the command queue

Methods

• All VVC procedures are defined in vvc_methods_pkg.vhd (dedicated to this VVC).

• See Common VVC Methods for procedures which are common to all VVCs.

• It is also possible to send a multicast to all instances of a VVC with ALL_INSTANCES as parameter for vvc_instance_idx.

• All parameters in brackets are optional.

Caution

Orange description is preliminary.

axilite_write()

Adds a write command to the AXI4-Lite VVC executor queue, which will distribute this command to the various channel executors which in turn will run as soon as all preceding commands have completed. When the command is scheduled to run, the executors call the AXI4-Lite procedures in axilite_channel_handler_pkg.vhd. This procedure can be called with or without byte_enable constant. When not set, byte_enable is set to all ‘1’, indicating that all bytes are valid.

axilite_write(VVCT, vvc_instance_idx, addr, data, [byte_enable,] msg, [scope])

Object	Name	Dir.	Type	Description
signal	VVCT	inout	t_vvc_target_record	VVC target type compiled into each VVC in order to differentiate between VVCs
constant	vvc_instance_idx	in	integer	Instance number of the VVC
constant	addr	in	unsigned	The address of an AXI4-Lite accessible register
constant	data	in	std_logic_vector	The data value to be written to the addressed register
constant	byte_enable	in	std_logic_vector	This argument selects which bytes to use (all ‘1’ means all bytes are updated)
constant	msg	in	string	A custom message to be appended in the log/alert
constant	scope	in	string	Describes the scope from which the log/alert originates. Default value is C_VVC_CMD_SCOPE_DEFAULT.

-- Examples:
axilite_write(AXILITE_VVCT, 0, x"0011A000", x"F102", "Writing data to Peripheral 1", C_SCOPE);
axilite_write(AXILITE_VVCT, 0, C_ADDR_PERIPHERAL_1, x"F102", b"11", "Writing data to Peripheral 1", C_SCOPE);
axilite_write(AXILITE_VVCT, 0, C_ADDR_DMA, x"1155F102", "Writing data to DMA", C_SCOPE);

axilite_read()

Adds a read command to the AXI4-Lite VVC executor queue, which will distribute this command to the various channel executors which in turn will run as soon as all preceding commands have completed. When the command is scheduled to run, the executors call the AXI4-Lite procedures in axilite_channel_handler_pkg.vhd.

The value read from DUT will not be returned in this procedure call since it is non-blocking for the sequencer/caller, but the read data will be stored in the VVC for a potential future fetch (see example with fetch_result below). If the data_routing is set to TO_SB, the read data will be sent to the AXI4-Lite VVC dedicated scoreboard where it will be checked against the expected value (provided by the testbench).

axilite_read(VVCT, vvc_instance_idx, addr, [data_routing,] msg, [scope])

Object	Name	Dir.	Type	Description
signal	VVCT	inout	t_vvc_target_record	VVC target type compiled into each VVC in order to differentiate between VVCs
constant	vvc_instance_idx	in	integer	Instance number of the VVC
constant	addr	in	unsigned	The address of an AXI4-Lite accessible register
constant	data_routing	in	t_data_routing	Selects the destination of the read data
constant	msg	in	string	A custom message to be appended in the log/alert
constant	scope	in	string	Describes the scope from which the log/alert originates. Default value is C_VVC_CMD_SCOPE_DEFAULT.

-- Examples:
axilite_read(AXILITE_VVCT, 0, x"00099555", "Read from Peripheral 1", C_SCOPE);
axilite_read(AXILITE_VVCT, 0, C_ADDR_IO, "Read from IO device", C_SCOPE);

-- Example with fetch_result() call: Result is placed in v_result
variable v_cmd_idx         : natural;                       -- Command index for the last read
variable v_result          : work.vvc_cmd_pkg.t_vvc_result; -- Result from read
...
axilite_read(AXILITE_VVCT, 0, x"112252AA", "Read from Peripheral 1");
v_cmd_idx := get_last_received_cmd_idx(AXILITE_VVCT, 0);
await_completion(AXILITE_VVCT, 0, v_cmd_idx, 100 ns, "Wait for read to finish");
fetch_result(AXILITE_VVCT, 0, v_cmd_idx, v_result, "Fetching result from read operation");

Hint

t_vvc_result is defined in the corresponding vvc_cmd_pkg.vhd for the VIP.

axilite_check()

Adds a check command to the AXI4-Lite VVC executor queue, which will distribute this command to the various channel executors which in turn will run as soon as all preceding commands have completed. When the command is scheduled to run, the executors call the AXI4-lite procedures in axilite_channel_handler_pkg.vhd. The axilite_check() procedure will perform a read operation, then check if the read data is equal to the ‘data’ parameter. If the read data is not equal to the expected data, an alert with severity ‘alert_level’ will be issued. The read data will not be stored by this procedure.

axilite_check(VVCT, vvc_instance_idx, addr, data, msg, [alert_level, [scope]])

Object	Name	Dir.	Type	Description
signal	VVCT	inout	t_vvc_target_record	VVC target type compiled into each VVC in order to differentiate between VVCs
constant	vvc_instance_idx	in	integer	Instance number of the VVC
constant	addr	in	unsigned	The address of an AXI4-Lite accessible register
constant	data	in	std_logic_vector	The data value to expect when reading the addressed register
constant	msg	in	string	A custom message to be appended in the log/alert
constant	alert_level	in	t_alert_level	Sets the severity for the alert. Default value is ERROR.
constant	scope	in	string	Describes the scope from which the log/alert originates. Default value is C_VVC_CMD_SCOPE_DEFAULT.

-- Examples:
axilite_check(AXILITE_VVCT, 0, x"00099555", x"393B", "Check data from Peripheral 1", ERROR, C_SCOPE);

Activity Watchdog

The VVCs support a centralized VVC activity register which the activity watchdog uses to monitor the VVC activities. The VVCs will register their presence to the VVC activity register at start-up, and report when ACTIVE and INACTIVE, using dedicated VVC activity register methods, and trigger the global_trigger_vvc_activity_register signal during simulations. The activity watchdog is continuously monitoring the VVC activity register for VVC inactivity and raises an alert if no VVC activity is registered within the specified timeout period.

Include activity_watchdog(num_exp_vvc, timeout, [alert_level, [msg]]) in the testbench to start using the activity watchdog. Note that setting the exact number of expected VVCs in the VVC activity register can be omitted by setting num_exp_vvc = 0.

More information can be found in Essential Mechanisms - Activity Watchdog.

Transaction Info

This VVC supports transaction info, a UVVM concept for distributing transaction information in a controlled manner within the complete testbench environment. The transaction info may be used in many different ways, but the main purpose is to share information directly from the VVC to a DUT model.

AXI4-Lite transaction info record fields. Transaction Type: t_base_transaction (BT) - accessible via shared_axilite_vvc_transaction_info.bt_wr and shared_axilite_vvc_transaction_info.bt_rd

Info field	Type	Default	Description
operation	t_operation	NO_OPERATION	Current VVC operation, e.g. INSERT_DELAY, POLL_UNTIL, READ, WRITE
vvc_meta	t_vvc_meta	C_VVC_META_DEFAULT	VVC meta data of the executing VVC command
-> msg	string	“”	Message of executing VVC command
-> cmd_idx	integer	-1	Command index of executing VVC command
transaction_status	t_transaction_status	INACTIVE	Set to INACTIVE, IN_PROGRESS, FAILED or SUCCEEDED during a transaction

AXI4-Lite transaction info record fields. Transaction type: t_arw_transaction (ST) - accessible via shared_axilite_vvc_transaction_info.st_aw and shared_axilite_vvc_transaction_info.st_ar

Info field	Type	Default	Description
operation	t_operation	NO_OPERATION	Current VVC operation, e.g. INSERT_DELAY, POLL_UNTIL, READ, WRITE
arwaddr	unsigned(31 downto 0)	0x0	The address for a read or write transaction
vvc_meta	t_vvc_meta	C_VVC_META_DEFAULT	VVC meta data of the executing VVC command
-> msg	string	“”	Message of executing VVC command
-> cmd_idx	integer	-1	Command index of executing VVC command
transaction_status	t_transaction_status	INACTIVE	Set to INACTIVE, IN_PROGRESS, FAILED or SUCCEEDED during a transaction

AXI4-Lite transaction info record fields. Transaction type: t_w_transaction (ST) - accessible via shared_axilite_vvc_transaction_info.st_w

Info field	Type	Default	Description
operation	t_operation	NO_OPERATION	Current VVC operation, e.g. INSERT_DELAY, POLL_UNTIL, READ, WRITE
wdata	std_logic_vector(255 downto 0)	0x0	Write data
wstrb	std_logic_vector(31 downto 0)	0x0	Write strobe
vvc_meta	t_vvc_meta	C_VVC_META_DEFAULT	VVC meta data of the executing VVC command
-> msg	string	“”	Message of executing VVC command
-> cmd_idx	integer	-1	Command index of executing VVC command
transaction_status	t_transaction_status	INACTIVE	Set to INACTIVE, IN_PROGRESS, FAILED or SUCCEEDED during a transaction

AXI4-Lite transaction info record fields. Transaction type: t_b_transaction (ST) - accessible via shared_axilite_vvc_transaction_info.st_b

Info field	Type	Default	Description
operation	t_operation	NO_OPERATION	Current VVC operation, e.g. INSERT_DELAY, POLL_UNTIL, READ, WRITE
vvc_meta	t_vvc_meta	C_VVC_META_DEFAULT	VVC meta data of the executing VVC command
-> msg	string	“”	Message of executing VVC command
-> cmd_idx	integer	-1	Command index of executing VVC command
transaction_status	t_transaction_status	INACTIVE	Set to INACTIVE, IN_PROGRESS, FAILED or SUCCEEDED during a transaction

AXI4-Lite transaction info record fields. Transaction type: t_r_transaction (ST) - accessible via shared_axilite_vvc_transaction_info.st_r

Info field	Type	Default	Description
operation	t_operation	NO_OPERATION	Current VVC operation, e.g. INSERT_DELAY, POLL_UNTIL, READ, WRITE
rdata	std_logic_vector(255 downto 0)	0x0	Read data
vvc_meta	t_vvc_meta	C_VVC_META_DEFAULT	VVC meta data of the executing VVC command
-> msg	string	“”	Message of executing VVC command
-> cmd_idx	integer	-1	Command index of executing VVC command
transaction_status	t_transaction_status	INACTIVE	Set to INACTIVE, IN_PROGRESS, FAILED or SUCCEEDED during a transaction

More information can be found in Essential Mechanisms - Distribution of Transaction Info.

Scoreboard

This VVC has built in Scoreboard functionality where data can be routed by setting the TO_SB parameter in supported method calls, i.e. axilite_read(). Note that the data is only stored in the scoreboard and not accessible with the fetch_result() method when the TO_SB parameter is applied. The AXI4-Lite scoreboard is accessible from the testbench as a shared variable AXILITE_VVC_SB, located in the vvc_methods_pkg.vhd, e.g.

AXILITE_VVC_SB.add_expected(C_AXILITE_VVC_IDX, pad_axilite_sb(v_expected), "Adding expected");

The AXI4-Lite scoreboard is per default 256 bits wide standard logic vector. When sending expected result to the scoreboard, where the result width is smaller than the default scoreboard width, we recommend zero-padding the data with the pad_axilite_sb() function, e.g.

AXILITE_VVC_SB.add_expected(<AXI-Lite VVC instance number>, pad_axilite_sb(<exp data>));

See the Bitvis VIP Scoreboard for a complete list of available commands and additional information. All of the listed Generic Scoreboard commands are available for the AXI4-Lite VVC scoreboard using the AXILITE_VVC_SB.

Unwanted Activity Detection

This VVC supports detection of unwanted activity from the DUT. This mechanism will give an alert if the DUT generates any unexpected bus activity. It assures that no data is output from the DUT when it is not expected, i.e. read/receive/check/expect VVC methods are not called. Once the VVC is inactive, it starts to monitor continuously on the DUT outputs. When unwanted activity is detected, the VVC issues an alert.

The unwanted activity detection can be configured from the central testbench sequencer, where the severity of alert can be changed to a different value. To disable this feature in the testbench, e.g.

shared_axilite_vvc_config(C_VVC_INDEX).unwanted_activity_severity := NO_ALERT;

Note that the ready signals (awready, wready, arready) are not monitored in this VVC. The ready signals are allowed to be set independently of the valid signals (awvalid, wvalid, arvalid), and there is no method to differentiate between the unwanted activity and intended activity. See the AXI4-Lite protocol specification for more information.

The unwanted activity detection is ignored when the valid signals (bvalid, rvalid) go low within one clock period after the VVC becomes inactive. This is to handle the situation when the read command exits before the next rising edge, causing signal transitions during the first clock cycle after the VVC is inactive.

For AXI4-Lite VVC, the unwanted activity detection feature is enabled by default with severity ERROR.

More information can be found in Essential Mechanisms - Unwanted Activity Detection.

Compilation

The AXI4-Lite VVC must be compiled with VHDL-2008 or newer. It is dependent on the following libraries:

• UVVM Utility Library (UVVM-Util)

• UVVM VVC Framework

• Bitvis VIP Scoreboard

• AXI4-Lite BFM

Before compiling the AXI4-Lite VVC, assure that uvvm_util, uvvm_vvc_framework and bitvis_vip_scoreboard have been compiled.

See Essential Mechanisms - Compile Scripts for information about compile scripts.

Compile order for the AXI4-Lite VVC

Compile to library	File	Comment
bitvis_vip_axilite	axilite_bfm_pkg.vhd	AXI4-Lite BFM
bitvis_vip_axilite	transaction_pkg.vhd	AXI4-Lite transaction package with DTT types, constants, etc.
bitvis_vip_axilite	vvc_cmd_pkg.vhd	AXI4-Lite VVC command types and operations
bitvis_vip_axilite	axilite_channel_handler_pkg.vhd	Package containing procedures for accessing AXI4-Lite channels. Only for use by the VVC.
bitvis_vip_axilite	../uvvm_vvc_framework/src_target_dependent/td_target_support_pkg.vhd	UVVM VVC target support package, compiled into this VVC library
bitvis_vip_axilite	../uvvm_vvc_framework/src_target_dependent/td_vvc_framework_common_methods_pkg.vhd	Common UVVM framework methods compiled into the this VVC library
bitvis_vip_axilite	vvc_sb_pkg.vhd	AXI4-Lite VVC scoreboard
bitvis_vip_axilite	vvc_methods_pkg.vhd	AXI4-Lite VVC methods
bitvis_vip_axilite	../uvvm_vvc_framework/src_target_dependent/td_queue_pkg.vhd	UVVM queue package for this VVC
bitvis_vip_axilite	../uvvm_vvc_framework/src_target_dependent/td_vvc_entity_support_pkg.vhd	UVVM VVC entity support compiled into this VVC library
bitvis_vip_axilite	axilite_vvc.vhd	AXI4-Lite VVC
bitvis_vip_axilite	vvc_context.vhd	AXI4-Lite VVC context file

Simulator compatibility and setup

• See Prerequisites for a list of supported simulators.

• For required simulator setup see UVVM-Util Simulator compatibility and setup.

Additional Documentation

For more information on the AXI4-Lite specification, refer to “AMBA® AXI™ and ACE™ Protocol Specification”, Part B (ARM IHI 0022G), available from ARM.

Important

• This is a simplified Verification IP (VIP) for AXI4-Lite.

• The given VIP complies with the basic AXI4-Lite protocol and thus allows a normal access towards an AXI4-Lite interface.

• This VIP is not an AXI4-Lite protocol checker.

• For a more advanced VIP please contact UVVM support at info@uvvm.org

Note

Disclaimer: This IP and any part thereof are provided “as is”, without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and non-infringement. In no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with this IP.