External VIP APB

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BFM
VVC

BFM

BFM functionality is implemented in apb_bfm_pkg.vhd

Signal Record

t_apb_if

Record element	Type
pclk	std_logic
paddr	std_logic_vector
pprot	std_logic_vector(2 downto 0)
psel	std_logic
penable	std_logic
pwrite	std_logic
pwdata	std_logic_vector
pstrb	std_logic_vector
prdata	std_logic_vector
pready	std_logic
pslverr	std_logic

Note

BFM calls can also be made with listing of single signals rather than t_apb_if.

Configuration Record

t_apb_bfm_config

Default value for the record is C_APB_BFM_CONFIG_DEFAULT.

Record element	Type	Default	Description
max_wait_cycles	natural	1000	The maximum number of clock cycles to wait for the DUT ready signal before reporting a timeout alert
max_wait_cycles_severity	t_alert_level	FAILURE	The above timeout will have this severity
clock_period	time	C_UNDEFINED_TIME	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	C_UNDEFINED_TIME	Generated signals setup time. Suggested value is clock_period/4. An alert is reported if setup_time exceeds clock_period/2.
hold_time	time	C_UNDEFINED_TIME	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 always wait for the first falling edge of the clock. Then the interface output signals will be set up immediately. After that, the BFM will wait for the rising edge of the clock, sample or set relevant interface signals (if any), and estimate the clock period. The BFM will deactivate potential interface output signals and exit ¼ clock period after a succeeding rising edge. When set to SYNC_WITH_SETUP_AND_HOLD the BFM will always wait for the configured setup time before the first rising edge of the clock. Then the interface output signals will be set up immediately. After that, the BFM will wait for the rising edge of the clock, and sample or set relevant interface signals (if any). Note that the clock period needs to be configured in this mode. The BFM will deactivate potential interface output signals and exit after the configured hold time after a succeeding rising edge.
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.
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

Methods

The record t_apb_if can be replaced with the signals listed in said record.
All signals are active high.
All parameters in brackets are optional.

apb_write()

Writes the given data to the given address on the DUT, using the APB protocol:

1. During the setup phase:
    a. paddr is set to addr_value
    b. pwdata is set to data_value
    c. pprot is set to protection
    d. pstrb is set to byte_enable
    e. psel is set to '1'
    f. pwrite is set to '1'
    g. penable is set to '0'
2. During the access phase:
    a. penable is set to '1'
    b. the BFM waits for pready to be '1'
3. Before exiting the procedure:
    e. psel is set to '0'
    g. penable is set to '0'

The procedure reports an alert if pready signal is not set to ‘1’ within ‘config.max_wait_cycles’ after penable is set to ‘1’ (alert_level: config.max_wait_cycles_severity).

apb_write(addr_value, data_value, byte_enable, protection, msg, apb_if, [scope, [msg_id_panel, [config]]])

Object	Name	Dir.	Type	Description
constant	addr_value	in	unsigned	The memory address of the peripheral being accessed
constant	data_value	in	std_logic_vector	The data value to be written to the memory address
constant	byte_enable	in	std_logic_vector	Each bit indicates which byte in data_value is valid
constant	protection	in	std_logic_vector(2 downto 0)	Indicates normal, privileged or secure protection levels and whether it’s a data or instruction access
constant	msg	in	string	A custom message to be appended in the log/alert
signal	apb_if	inout	t_apb_if	APB signal interface record
constant	scope	in	string	Describes the scope from which the log/alert originates. Default value is C_BFM_SCOPE (“APB BFM”).
constant	msg_id_panel	in	t_msg_id_panel	Controls verbosity within a specified scope. Default value is shared_msg_id_panel. For more information see Scope of Verbosity Control.
constant	config	in	t_apb_bfm_config	Configuration of BFM behavior and restrictions. Default value is C_APB_BFM_CONFIG_DEFAULT.

-- Examples:
apb_write(x"1000", x"AA55", "1111", "000", "Write data to Peripheral 1", apb_if);
apb_write(x"1000", x"AA55", "1111", "000", "Write data to Peripheral 1", apb_if, C_SCOPE, shared_msg_id_panel, C_APB_BFM_CONFIG_DEFAULT);

-- Suggested usage (requires local overload, see 'Local BFM overloads' section):
apb_write(C_ADDR_REG_1, x"AA55", "Write data to Peripheral 1");

apb_read()

Reads data from the DUT at the given address, using the APB protocol:

1. During the setup phase:
    a. paddr is set to addr_value
    b. pprot is set to protection
    c. psel is set to '1'
    d. pwrite is set to '0'
    e. penable is set to '0'
2. During the access phase:
    a. penable is set to '1'
    b. the BFM waits for pready to be '1'
3. Before exiting the procedure:
    e. psel is set to '0'
    g. penable is set to '0'

The procedure reports an alert if pready signal is not set to ‘1’ within ‘config.max_wait_cycles’ after penable is set to ‘1’ (alert_level: config.max_wait_cycles_severity).

apb_read(addr_value, data_value, protection, msg, apb_if, [scope, [msg_id_panel, [config]]])

Object	Name	Dir.	Type	Description
constant	addr_value	in	unsigned	The memory address of the peripheral being accessed
variable	data_value	out	std_logic_vector	The data value read from the addressed register
constant	protection	in	std_logic_vector(2 downto 0)	Indicates normal, privileged or secure protection levels and whether it’s a data or instruction access
constant	msg	in	string	A custom message to be appended in the log/alert
signal	apb_if	inout	t_apb_if	APB signal interface record
constant	scope	in	string	Describes the scope from which the log/alert originates. Default value is C_BFM_SCOPE (“APB BFM”).
constant	msg_id_panel	in	t_msg_id_panel	Controls verbosity within a specified scope. Default value is shared_msg_id_panel. For more information see Scope of Verbosity Control.
constant	config	in	t_apb_bfm_config	Configuration of BFM behavior and restrictions. Default value is C_APB_BFM_CONFIG_DEFAULT.

-- Examples:
apb_read(x"1000", v_data_out, "000", "Read from Peripheral 1", apb_if);
apb_read(x"1000", v_data_out, "000", "Read from Peripheral 1", apb_if, C_SCOPE, shared_msg_id_panel, C_APB_BFM_CONFIG_DEFAULT);

-- Suggested usage (requires local overload, see 'Local BFM overloads' section):
apb_read(C_ADDR_REG_1, v_data_out, "Read from Peripheral 1");

apb_check()

Reads data from the DUT at the given address, using the APB protocol described under apb_read(). After reading data from the APB bus, the read data is compared with the expected data.

If the check was successful, and the read data matches the expected data, a log message is written with ID ‘config.id_for_bfm’.
If the read data did not match the expected data, an alert with severity ‘alert_level’ will be reported.
The procedure will also report alerts for the same conditions as the apb_read() procedure.

apb_check(addr_value, data_exp, protection, msg, apb_if, [alert_level, [scope, [msg_id_panel, [config]]]])

Object	Name	Dir.	Type	Description
constant	addr_value	in	unsigned	The memory address of the peripheral being accessed
constant	data_exp	in	std_logic_vector	The data value to be expect when reading the memory address
constant	protection	in	std_logic_vector(2 downto 0)	Indicates normal, privileged or secure protection levels and whether it’s a data or instruction access
constant	msg	in	string	A custom message to be appended in the log/alert
signal	apb_if	inout	t_apb_if	APB 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 (“APB BFM”).
constant	msg_id_panel	in	t_msg_id_panel	Controls verbosity within a specified scope. Default value is shared_msg_id_panel. For more information see Scope of Verbosity Control.
constant	config	in	t_apb_bfm_config	Configuration of BFM behavior and restrictions. Default value is C_APB_BFM_CONFIG_DEFAULT.

-- Examples:
apb_check(x"1155", x"123B", "000", "Check data from Peripheral 1", apb_if);
apb_check(x"1155", x"123B", "000", "Check data from Peripheral 1", apb_if, ERROR, C_SCOPE, shared_msg_id_panel, C_APB_BFM_CONFIG_DEFAULT);

-- Suggested usage (requires local overload, see 'Local BFM overloads' section):
apb_check(C_ADDR_REG_1, x"123B", "Check data from Peripheral 1");

apb_poll_until()

Reads data from the DUT at the given address, using the APB protocol described under apb_read(). After reading data from the DUT, the read data is compared with the expected data. If the read data does not match the expected data, the process is repeated until one or more of the following occurs:

The read data matches the expected data
The number of read retries is equal to ‘max_polls’
The time between start of apb_poll_until procedure and now is greater than ‘timeout’
The terminate_loop signal is set to ‘1’

If the procedure exits because of 2. or 3. an alert with severity ‘alert_level’ is issued. If either ‘max_polls’ or ‘timeout’ is set to 0 (ns), this constraint will be ignored and interpreted as no limit.

If the check was successful, and the read data matches the expected data, a log message is written with ID ‘config.id_for_bfm’.
If the read data did not match the expected data, an alert with severity ‘alert_level’ will be reported.
If the procedure is terminated using ‘terminate_loop’ a log message with ID ID_TERMINATE_CMD will be issued.
The procedure will also report alerts for the same conditions as the apb_read() procedure.

apb_poll_until(addr_value, data_exp, protection, max_polls, timeout, msg, apb_if, terminate_loop, [alert_level, [scope, [msg_id_panel, [config]]]])

Object	Name	Dir.	Type	Description
constant	addr_value	in	unsigned	The memory address of the peripheral being accessed
constant	data_exp	in	std_logic_vector	The data value to be expect when reading the memory address
constant	protection	in	std_logic_vector(2 downto 0)	Indicates normal, privileged or secure protection levels and whether it’s a data or instruction access
constant	max_polls	in	integer	The maximum number of polls (reads) before the expected data must be found. Exceeding this limit results in an alert with severity ‘alert_level’. Note that 0 means no limit.
constant	timeout	in	time	The maximum time to pass before the expected data must be found. Exceeding this limit results in an alert with severity ‘alert_level’. Note that 0 ns means no timeout.
constant	msg	in	string	A custom message to be appended in the log/alert
signal	apb_if	inout	t_apb_if	APB signal interface record
signal	terminate_loop	in	std_logic	External control of loop termination to e.g. stop polling prematurely
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 (“APB BFM”).
constant	msg_id_panel	in	t_msg_id_panel	Controls verbosity within a specified scope. Default value is shared_msg_id_panel. For more information see Scope of Verbosity Control.
constant	config	in	t_apb_bfm_config	Configuration of BFM behavior and restrictions. Default value is C_APB_BFM_CONFIG_DEFAULT.

-- Examples:
apb_poll_until(x"1155", x"0A5D", "000", 10, 100 ns, "Poll for data from Peripheral 1", apb_if, terminate_loop);
apb_poll_until(x"1155", x"0A5D", "000", 10, 100 ns, "Poll for data from Peripheral 1", apb_if, terminate_loop, ERROR, C_SCOPE, shared_msg_id_panel, C_APB_BFM_CONFIG_DEFAULT);

-- Suggested usage (requires local overload, see 'Local BFM overloads' section):
apb_poll_until(C_ADDR_REG_1, x"05AD", "Poll register 1 until expected data is found");
apb_poll_until(C_ADDR_REG_1, x"05AD", C_MAX_POLLS, C_TIMEOUT, "Poll register 1 until expected data is found");

init_apb_if_signals()

Initializes the APB interface. All the BFM outputs are set to ‘0’, and BFM inputs are set to ‘Z’.

t_apb_if := init_apb_if_signals(addr_width, data_width)

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

-- Examples:
apb_if <= init_apb_if_signals(apb_if.paddr'length, apb_if.pwdata'length);

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.

apb_write(C_ADDR_REG_1, x"AA55", "Write data to Peripheral 1");

rather than

apb_write(C_ADDR_REG_1, x"AA55", "1111", "000", "Write data to Peripheral 1", apb_if, C_SCOPE, shared_msg_id_panel, C_APB_BFM_CONFIG_DEFAULT);

By defining the local overload as e.g.

procedure apb_write(
  constant addr_value : in unsigned;
  constant data_value : in std_logic_vector;
  constant msg        : in string) is
  variable v_byte_enable : std_logic_vector((data_value'length / 8) - 1 downto 0) := (others => '1');
begin
  apb_write(addr_value,           -- Keep as is
            data_value,           -- Keep as is
            v_byte_enable,        -- This could also be an input if needed
            C_DEFAULT_PROTECTION, -- This could also be an input if needed
            msg,                  -- Keep as is
            apb_if,               -- Signal must be visible in local process scope
            C_SCOPE,              -- Use the default
            shared_msg_id_panel,  -- Use global, shared msg_id_panel
            C_APB_CONFIG_LOCAL);  -- Use locally defined configuration or C_APB_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 APB specification, refer to “AMBA® APB Protocol Specification” (ARM IHI 0024D), available from ARM.

Important

This is a simplified Bus Functional Model (BFM) for APB.
The given BFM complies with the basic APB protocol and thus allows a normal access towards an APB interface.
This BFM is not an APB protocol checker.
For a more advanced BFM please contact UVVM support at info@uvvm.org

VVC

VVC functionality is implemented in apb_vvc.vhd
For general information see VVC Mechanisms and Features.

Entity

Generics

Name	Type	Default	Description
GC_ADDR_WIDTH	integer	32	Width of the APB address bus
GC_DATA_WIDTH	integer	32	Width of the APB data bus
GC_INSTANCE_IDX	natural	0	Instance number to assign the VVC. Maximum value is defined by C_APB_VVC_MAX_INSTANCE_NUM in adaptations_pkg.
GC_APB_CONFIG	t_apb_bfm_config	C_APB_BFM_CONFIG_DEFAULT	Configuration for the APB 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

Note

Default values for the cmd/result queue generics are defined in adaptations_pkg.

Signals

Object	Name	Dir.	Type	Description
signal	apb_vvc_master_if	inout	t_apb_if	APB signal interface record

In this VVC, the interface has been encapsulated in a signal record of type t_apb_if in order to improve readability of the code. Since the APB 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 apb_if : t_apb_if(paddr(C_ADDR_WIDTH - 1 downto 0),
                         pwdata(C_DATA_WIDTH - 1 downto 0),
                         pstrobe((C_DATA_WIDTH / 8) - 1 downto 0),
                         prdata(C_DATA_WIDTH - 1 downto 0));

Configuration Record

vvc_config accessible via shared_apb_vvc_config

Record element	Type	Default	Description
inter_bfm_delay	t_inter_bfm_delay	C_APB_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_apb_bfm_config	C_APB_BFM_CONFIG_DEFAULT	Configuration for the APB 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.
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_apb_vvc_config(C_VVC_IDX).inter_bfm_delay.delay_in_time := 50 ns;
shared_apb_vvc_config(C_VVC_IDX).bfm_config.id_for_bfm := ID_BFM;

Status Record

vvc_status accessible via shared_apb_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.

Note

Some parameters in the VVC procedures are unconstrained for flexibility. However, the maximum sizes of such parameters need to be defined for the VVC framework. For this VVC, the following maximum values can be configured from adaptations_pkg:

C_APB_VVC_CMD_DATA_MAX_LENGTH

Maximum pwdata/prdata length

C_APB_VVC_CMD_ADDR_MAX_LENGTH

Maximum paddr length

C_APB_VVC_CMD_BYTE_ENABLE_MAX_LENGTH

Maximum pstrb length

C_APB_VVC_CMD_STRING_MAX_LENGTH

Maximum msg length

apb_write()

Adds a write command to the APB VVC executor queue, which will run as soon as all preceding commands have completed. When the command is scheduled to run, the executor calls the BFM apb_write() procedure.

apb_write(VVCT, vvc_instance_idx, addr, data, [byte_enable, protection,] 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 memory address of the peripheral being accessed
constant	data	in	std_logic_vector	The data value to be written to the memory address
constant	byte_enable	in	std_logic_vector	Each bit indicates which byte in data is valid
constant	protection	in	std_logic_vector(2 downto 0)	Indicates normal, privileged or secure protection levels and whether it’s a data or instruction access
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 defined in adaptations_pkg.

-- Examples:
apb_write(APB_VVCT, 0, x"1000", x"4000", "Write data to Peripheral 1", C_SCOPE);
apb_write(APB_VVCT, 0, x"1000", x"4000", "1111", "000" "Write data to Peripheral 1", C_SCOPE);

-- It is recommended to use constants to improve the readability of the code, e.g.:
apb_write(APB_VVCT, 0, C_ADDR_REG_1, x"4000", C_BYTE_ENABLE, C_NON_SECURE, "Write data to Peripheral 1");

apb_read()

Adds a read command to the APB VVC executor queue, which will run as soon as all preceding commands have completed. When the command is scheduled to run, the executor calls the BFM apb_read() procedure.

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 APB VVC dedicated scoreboard where it will be checked against the expected value (provided by the testbench).

apb_read(VVCT, vvc_instance_idx, addr, [protection,] [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 memory address of the peripheral being accessed
constant	protection	in	std_logic_vector(2 downto 0)	Indicates normal, privileged or secure protection levels and whether it’s a data or instruction access
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 defined in adaptations_pkg.

-- Examples:
apb_read(APB_VVCT, 0, x"1000", "Read from Peripheral 1", C_SCOPE);
apb_read(APB_VVCT, 0, x"1002", TO_SB, "Read from Peripheral 1 and send to Scoreboard", C_SCOPE);

-- It is recommended to use constants to improve the readability of the code, e.g.:
apb_read(APB_VVCT, 0, C_ADDR_REG_1, "Read from Peripheral 1");

-- 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.
...
apb_read(APB_VVCT, 0, C_ADDR_REG_1, "Read from Peripheral 1";
v_cmd_idx := get_last_received_cmd_idx(APB_VVCT, 0);
await_completion(APB_VVCT, 0, v_cmd_idx, 1 us, "Wait for read to finish");
fetch_result(APB_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.

apb_check()

Adds a check command to the APB VVC executor queue, which will run as soon as all preceding commands have completed. When the command is scheduled to run, the executor calls the BFM apb_check() procedure. The apb_check() procedure will perform a read operation, then check if the read data is equal to the expected data in the data parameter. If the read data is not equal to the expected data parameter, an alert with severity ‘alert_level’ will be issued. The read data will not be stored in this procedure.

apb_check(VVCT, vvc_instance_idx, addr, data, [protection,] 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 memory address of the peripheral being accessed
constant	data	in	std_logic_vector	The expected data value to be read from the addressed register
constant	protection	in	std_logic_vector(2 downto 0)	Indicates normal, privileged or secure protection levels and whether it’s a data or instruction access
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 defined in adaptations_pkg.

-- Examples:
apb_check(APB_VVCT, 0, x"1155", x"123B", "Check data from Peripheral 1");
apb_check(APB_VVCT, 0, x"1155", x"123B", "000", "Check data from Peripheral 1", TB_ERROR, C_SCOPE):

-- It is recommended to use constants to improve the readability of the code, e.g.:
apb_check(APB_VVCT, 0, C_ADDR_REG_1, x"4000", C_NON_SECURE, "Check data from Peripheral 1");

apb_poll_until()

Adds a poll_until command to the APB VVC executor queue, which will run as soon as all preceding commands have completed. When the command is scheduled to run, the executor calls the BFM apb_poll_until() procedure. The apb_poll_until() procedure will perform a read operation, then check if the read data is equal to the data in the data parameter. If the read data is not equal to the expected data parameter, the process will be repeated until the read data is equal to the expected data, or the procedure is terminated by either a terminate command, a timeout or the poll limit set in max_polls. The read data will not be stored by this procedure.

apb_poll_until(VVCT, vvc_instance_idx, addr, data, [protection,] msg, [max_polls, [timeout, [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 memory address of the peripheral being accessed
constant	data	in	std_logic_vector	The expected data value to be read from the addressed register
constant	protection	in	std_logic_vector(2 downto 0)	Indicates normal, privileged or secure protection levels and whether it’s a data or instruction access
constant	msg	in	string	A custom message to be appended in the log/alert
constant	max_polls	in	integer	The maximum number of polls (reads) before the expected data must be found. Exceeding this limit results in an alert with severity ‘alert_level’. Note that 0 means no limit. Default value is 100.
constant	timeout	in	time	The maximum time to pass before the expected data must be found. Exceeding this limit results in an alert with severity ‘alert_level’. Note that 0 ns means no timeout. Default value is 1 us.
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 defined in adaptations_pkg.

-- Examples:
apb_poll_until(APB_VVCT, 0, x"1155", x"0ABD", "Poll for data from Peripheral 1");
apb_poll_until(APB_VVCT, 0, x"1155", x"0ABD", "000", "Poll for data from Peripheral 1", 5, 0 ns, TB_WARNING, C_SCOPE);

-- It is recommended to use constants to improve the readability of the code, e.g.:
apb_poll_until(APB_VVCT, 0, C_ADDR_REG_1, x"0ABD", "Poll for data from Peripheral 1 until expected data is found");

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.

APB transaction info record fields. Transaction Type: t_base_transaction (BT) - accessible via **shared_apb_vvc_transaction_info.bt**
Info field	Type	Default	Description
operation	t_operation	NO_OPERATION	Current VVC operation, e.g. INSERT_DELAY, POLL_UNTIL, READ, WRITE
address	unsigned(31 downto 0)	0x0	Address of the APB read or write transaction
data	std_logic_vector(31 downto 0)	0x0	Data for APB 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

APB transaction info record fields. Transaction type: t_compound_transaction (CT) - accessible via **shared_apb_vvc_transaction_info.ct**
Info field	Type	Default	Description
operation	t_operation	NO_OPERATION	Current VVC operation, e.g. INSERT_DELAY, POLL_UNTIL, READ, WRITE
address	unsigned(31 downto 0)	0x0	Address of the APB read or write transaction
data	std_logic_vector(31 downto 0)	0x0	Data for APB read or write transaction
max_polls	integer	1	Maximum number of polls allowed in the apb_poll_until() procedure. 0 means no limit.
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. apb_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 APB scoreboard is accessible from the testbench as a shared variable apb_vvc_sb, located in the vvc_methods_pkg.vhd, e.g.

apb_vvc_sb.add_expected(C_APB_VVC_IDX, pad_apb_sb(v_expected), "Adding expected");

The APB scoreboard is per default a 32 bits wide standard logic vector. When sending expected data to the scoreboard, where the data width is smaller than the default scoreboard width, we recommend zero-padding the data with the pad_apb_sb() function, e.g.

apb_vvc_sb.add_expected(<APB VVC instance number>, pad_apb_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 APB VVC scoreboard using the apb_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_apb_vvc_config(C_VVC_INDEX).unwanted_activity_severity := NO_ALERT;

Note that the pready signal is not monitored in this VVC. The pready signal is allowed to toggle whenever penable is low, and there is no method to differentiate between the unwanted activity and intended activity. See the APB protocol specification for more information on the pready signal.

For APB VVC, the unwanted activity detection is enabled by default with severity ERROR.

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

Compilation

The APB 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

APB BFM

Before compiling the APB 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 APB VVC
Compile to library	File	Comment
external_vip_apb	apb_bfm_pkg.vhd	APB BFM
external_vip_apb	transaction_pkg.vhd	APB transaction package with DTT types, constants, etc.
external_vip_apb	vvc_cmd_pkg.vhd	APB VVC command types and operations
external_vip_apb	../uvvm_vvc_framework/src_target_dependent/td_target_support_pkg.vhd	UVVM VVC target support package, compiled into this VVC library
external_vip_apb	../uvvm_vvc_framework/src_target_dependent/td_vvc_framework_common_methods_pkg.vhd	Common UVVM framework methods compiled into the this VVC library
external_vip_apb	vvc_sb_pkg.vhd	APB VVC scoreboard
external_vip_apb	vvc_methods_pkg.vhd	APB VVC methods
external_vip_apb	../uvvm_vvc_framework/src_target_dependent/td_queue_pkg.vhd	UVVM queue package for this VVC
external_vip_apb	../uvvm_vvc_framework/src_target_dependent/td_vvc_entity_support_pkg.vhd	UVVM VVC entity support compiled into this VVC library
external_vip_apb	apb_vvc.vhd	APB VVC
external_vip_apb	vvc_context.vhd	APB 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 APB specification, refer to “AMBA® APB Protocol Specification” (ARM IHI 0024D), available from ARM.

Important

This is a simplified Verification IP (VIP) for APB.
The given VIP complies with the basic APB protocol and thus allows a normal access towards an APB interface.
This VIP is not an APB 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.