Bitvis VIP SBI

Quick Access

• BFM

  • sbi_write()

  • sbi_read()

  • sbi_check()

  • sbi_poll_until()

  • init_sbi_if_signals()

• VVC

  • sbi_write()

  • sbi_read()

  • sbi_check()

  • sbi_poll_until()

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BFM

BFM functionality is implemented in sbi_bfm_pkg.vhd

Signal Record

t_sbi_if

Record element	Type
cs	std_logic
addr	unsigned
wena	std_logic
rena	std_logic
wdata	std_logic_vector
ready	std_logic
rdata	std_logic_vector

Note

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

• If using non-ready version, set ready to ‘1’ or set use_ready_signal to false.

Configuration Record

t_sbi_bfm_config

Default value for the record is C_SBI_BFM_CONFIG_DEFAULT.

Record element	Type	Default	Description
max_wait_cycles	integer	10	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
use_fixed_wait_cycles_read	boolean	false	When true, wait ‘fixed_wait_cycles_read’ after asserting rena signal, before sampling rdata
fixed_wait_cycles_read	natural	0	Number of clock cycles to wait after asserting rena signal, before sampling rdata
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.
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
use_ready_signal	boolean	true	Whether or not to use the interface ‘ready’ signal

Methods

• The record t_sbi_if can be replaced with the signals listed in said record.

• All signals are active high.

• All parameters in brackets are optional.

sbi_write()

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

1. - At 'config.clock_period'/4 before the first rising clock edge the bus lines are set:
    a. cs and wena are set to '1'
    b. rena is set to '0'
    c. addr is set to addr_value
    d. wdata is set to data_value
2a. - With ready-signalling:
    a. on the first rising edge the DUT ready signal is evaluated:
        * If ready is '1', cs and wena are set to '0' again 'config.clock_period'/4 after the last rising edge and the write
          procedure was successful.
        * If ready is '0', the procedure will wait one clock cycle and evaluate the ready signal again. This will repeat until
          ready is set to '1', or invoke an error if the process has repeated 'config.max_wait_cycles times'. A log message with ID
          'config.id_for_bfm_wait' is logged at the first wait.
2b. - Without ready-signalling:
    a. cs and wena are set to '0' again 'config.clock_period'/4 after the first rising edge

The procedure reports an alert if ready signal is not set to ‘1’ within ‘config.max_wait_cycles’ after cs and wena are set to ‘1’ (alert_level: config.max_wait_cycles_severity).

sbi_write(addr_value, data_value, msg, clk, sbi_if, [scope, [msg_id_panel, [config]]])

Object	Name	Dir.	Type	Description
constant	addr_value	in	unsigned	The address of a software accessible register
constant	data_value	in	std_logic_vector	The data value to be written to 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 SBI BFM
signal	sbi_if	inout	t_sbi_if	SBI signal interface record
constant	scope	in	string	Describes the scope from which the log/alert originates. Default value is C_BFM_SCOPE (“SBI 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_sbi_bfm_config	Configuration of BFM behavior and restrictions. Default value is C_SBI_BFM_CONFIG_DEFAULT.

-- Examples:
sbi_write(x"1000", x"55", "Write data to Peripheral 1", clk, sbi_if);
sbi_write(x"1000", x"55", "Write data to Peripheral 1", clk, sbi_if, C_SCOPE, shared_msg_id_panel, C_SBI_BFM_CONFIG_DEFAULT);

-- Suggested usage (requires local overload, see 'Local BFM overloads' section):
sbi_write(C_ADDR_UART_TX, x"40", "Set baud rate to 9600");

sbi_read()

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

1. At 'config.clock_period'/4 before the first rising clock edge the bus lines are set:
    a. cs and rena are set to '1'
    b. wena is set to '0'
    c. addr is set to addr_value
2a. With ready-signalling:
    a. On the first rising edge the DUT ready signal is evaluated:
        * If ready is '1', the data on the rdata line is returned to the reader in data_value.
        * If ready is '0', the procedure will wait one clock cycle and evaluate the ready signal again. This will repeat until
          ready is set to '1', or invoke an error if the process has repeated 'config.max_wait_cycles' times. A log message with
          ID 'config.id_for_bfm_wait' is logged at the first wait.
2b. Without ready-signalling:
    a. On the first rising edge the data on the rdata line is returned to the reader in data_value.
3. After 'config.clock_period'/4 cs and rena are set to '0' again

The procedure reports an alert if ready signal is not set to ‘1’ within ‘config.max_wait_cycles’ after cs and wena are set to ‘1’ (alert_level: config.max_wait_cycles_severity).

sbi_read(addr_value, data_value, msg, clk, sbi_if, [scope, [msg_id_panel, [config]]])

Object	Name	Dir.	Type	Description
constant	addr_value	in	unsigned	The address of a software accessible register
variable	data_value	out	std_logic_vector	The data value 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 SBI BFM
signal	sbi_if	inout	t_sbi_if	SBI signal interface record
constant	scope	in	string	Describes the scope from which the log/alert originates. Default value is C_BFM_SCOPE (“SBI 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_sbi_bfm_config	Configuration of BFM behavior and restrictions. Default value is C_SBI_BFM_CONFIG_DEFAULT.

-- Examples:
sbi_read(x"1000", v_data_out, "Read from Peripheral 1", clk, sbi_if);
sbi_read(x"1000", v_data_out, "Read from Peripheral 1", clk, sbi_if, C_SCOPE, shared_msg_id_panel, C_SBI_BFM_CONFIG_DEFAULT);

-- Suggested usage (requires local overload, see 'Local BFM overloads' section):
sbi_read(C_ADDR_UART_BAUD, v_data_out, "Read UART baud rate");

sbi_check()

Reads data from the DUT at the given address, using the SBI protocol described under sbi_read(). After reading data from the SBI 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 sbi_read() procedure.

sbi_check(addr_value, data_exp, msg, clk, sbi_if, [alert_level, [scope, [msg_id_panel, [config]]]])

Object	Name	Dir.	Type	Description
constant	addr_value	in	unsigned	The address of a software accessible register
constant	data_exp	in	std_logic_vector	The data value to expect when reading the addressed register. A mismatch results in an alert with severity ‘alert_level’.
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 SBI BFM
signal	sbi_if	inout	t_sbi_if	SBI 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 (“SBI 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_sbi_bfm_config	Configuration of BFM behavior and restrictions. Default value is C_SBI_BFM_CONFIG_DEFAULT.

-- Examples:
sbi_check(x"1155", x"3B", "Check data from Peripheral 1", clk, sbi_if);
sbi_check(x"1155", x"3B", "Check data from Peripheral 1", clk, sbi_if, ERROR, C_SCOPE, shared_msg_id_panel, C_SBI_BFM_CONFIG_DEFAULT);

-- Suggested usage (requires local overload, see 'Local BFM overloads' section):
sbi_check(C_ADDR_UART_RX, x"3B", "Check data from UART RX buffer");

sbi_poll_until()

Reads data from the DUT at the given address, using the SBI protocol described under sbi_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:

1. The read data matches the expected data

2. The number of read retries is equal to ‘max_polls’

3. The time between start of sbi_poll_until procedure and now is greater than ‘timeout’

4. 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 sbi_read() procedure.

sbi_poll_until(addr_value, data_exp, max_polls, timeout, msg, clk, sbi_if, terminate_loop, [alert_level, [scope, [msg_id_panel, [config]]]])

Object	Name	Dir.	Type	Description
constant	addr_value	in	unsigned	The address of a software accessible register
constant	data_exp	in	std_logic_vector	The data value to expect when reading the addressed register. A mismatch results in an alert with severity ‘alert_level’.
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	clk	in	std_logic	The clock signal used to read and write data in/out of the SBI BFM
signal	sbi_if	inout	t_sbi_if	SBI 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 (“SBI 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_sbi_bfm_config	Configuration of BFM behavior and restrictions. Default value is C_SBI_BFM_CONFIG_DEFAULT.

-- Examples:
sbi_poll_until(x"1155", x"0D", 10, 100 ns, "Poll for data from Peripheral 1", clk, sbi_if, terminate_loop);
sbi_poll_until(x"1155", x"0D", 10, 100 ns, "Poll for data from Peripheral 1", clk, sbi_if, terminate_loop, ERROR, C_SCOPE, shared_msg_id_panel, C_SBI_BFM_CONFIG_DEFAULT);

-- Suggested usage (requires local overload, see 'Local BFM overloads' section):
sbi_poll_until(C_ADDR_UART_RX, x"0D", "Poll UART RX buffer until CR is found");
sbi_poll_until(C_ADDR_UART_RX, x"0D", C_MAX_POLLS, C_TIMEOUT, "Poll UART RX buffer until CR is found");

init_sbi_if_signals()

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

t_sbi_if := init_sbi_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:
sbi_if <= init_sbi_if_signals(sbi_if.addr'length, sbi_if.wdata'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.

sbi_write(C_ADDR_UART_BAUDRATE, C_BAUDRATE_9600, "Set Baud-rate to 9600");

rather than

sbi_write(C_ADDR_UART_BAUDRATE, C_BAUDRATE_9600, "Set Baud-rate to 9600", clk, sbi_if, C_SCOPE, shared_msg_id_panel, C_SBI_CONFIG_DEFAULT);

By defining the local overload as e.g.

procedure sbi_write(
  constant addr_value : in unsigned;
  constant data_value : in std_logic_vector;
  constant msg        : in string) is
begin
  sbi_write(addr_value,          -- Keep as is
            data_value,          -- Keep as is
            msg,                 -- Keep as is
            clk,                 -- Signal must be visible in local process scope
            sbi_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_SBI_CONFIG_LOCAL); -- Use locally defined configuration or C_SBI_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

The SBI BFM is used in the IRQC example provided with the UVVM Utility Library. Thus, you can find info under:

• Making a simple, structured and efficient VHDL testbench – Step-by-step [PPT] (located in /uvvm_util/doc/Simple_TB_step_by_step.pps)

There is also a webinar available on ‘Making a simple, structured and efficient VHDL testbench – Step-by-step’ (via Aldec [1])

SBI protocol

SBI is our name for the simplest bus interface possible, one that has been used for decades in the electronics industry. Some think of it as a simple SRAM interface, but that is not a standard, and is probably understood and used in many different ways. Thus, we have defined a name and an exact behavior, with some flexibility.

SBI is a single cycle bus with an optional ready-signalling. The protocol for SBI with and without ready-signalling is given below. (Note that ready is always high in the without case). Data is sampled on rising edge a and b.

As can be seen from the figure all required signals including data input must be ready on the rising edge of the clock. This also applies for a read access, but the actual data output is provided combinatorial as soon as the combinational logic allows. Note that an active ‘cs’, a valid ‘addr’ and an active ‘wena’ or ‘rena’ is needed on the same active clock edge to be registered as a valid read or write. (Being active on two consecutive rising clocks will result in two consecutive accesses - with or without side-effects depending on the module’s internal functional logic.) ‘rdata’ will just ripple out for the right combination of ‘cs’, ‘addr’ and ‘rena’.

With this simple version, the designer has the option to provide input and/or output registers externally to allow a higher frequency (with added latency). SBI has optional ready-signalling (you may choose to have ready always high). When ‘ready’ is used it applies to both read and write accesses. For both read and write accesses all input signals must be held until ‘ready’ is active. For a read access, the output data may not be used (sampled) until ‘ready’ is active, but must do so on the first rising edge of the clock after ‘ready’ active.

Important

• This is a simplified Bus Functional Model (BFM) for SBI.

• The given BFM complies with the basic SBI protocol and thus allows a normal access towards a SBI interface.

• This BFM is not a SBI protocol checker.

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

---

VVC

• VVC functionality is implemented in sbi_vvc.vhd

• For general information see VVC Framework - Essential Mechanisms.

Entity

Generics

Name	Type	Default	Description
GC_ADDR_WIDTH	integer	8	Width of the SBI address bus
GC_DATA_WIDTH	integer	32	Width of the SBI data bus
GC_INSTANCE_IDX	natural	1	Instance number to assign the VVC
GC_SBI_CONFIG	t_sbi_bfm_config	C_SBI_BFM_CONFIG_DEFAULT	Configuration for the SBI 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	sbi_vvc_master_if	inout	t_sbi_if	SBI signal interface record

In this VVC, the interface has been encapsulated in a signal record of type t_sbi_if in order to improve readability of the code. Since the SBI 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 sbi_if : t_sbi_if(addr(C_ADDR_WIDTH - 1 downto 0),
                         wdata(C_DATA_WIDTH - 1 downto 0),
                         rdata(C_DATA_WIDTH - 1 downto 0));

Configuration Record

vvc_config accessible via shared_sbi_vvc_config

Record element	Type	Default	Description
inter_bfm_delay	t_inter_bfm_delay	C_SBI_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_sbi_bfm_config	C_SBI_BFM_CONFIG_DEFAULT	Configuration for the SBI 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_sbi_vvc_config(1).inter_bfm_delay.delay_in_time := 50 ns;
shared_sbi_vvc_config(1).bfm_config.id_for_bfm := ID_BFM;

Status Record

vvc_status accessible via shared_sbi_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.

sbi_write()

Adds a write command to the SBI VVC executor queue, which will run as soon as all preceding commands have completed. It has two variants using either just data for a basic single transaction, or num_words + randomization for a more advanced version.

When the basic write command is scheduled to run, the executor calls the BFM sbi_write() procedure.

When the more advanced randomization command is applied, the basic BFM sbi_write() transaction is executed num_words times with new random data each time – according to the given randomization profile. Current defined randomization profiles are: RANDOM: Standard uniform random. This is provided as an example.

sbi_write(VVCT, vvc_instance_idx, addr, data, msg, [scope])
sbi_write(VVCT, vvc_instance_idx, addr, num_words, randomisation, 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 a SW accessible register. Could be offset or full address depending on the DUT.
constant	data	in	std_logic_vector	The data value to be written to the addressed register
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:
sbi_write(SBI_VVCT, 0, x"1000", x"40", "Set UART baud rate to 9600", C_SCOPE);
sbi_write(SBI_VVCT, 0, x"1001", 7, RANDOM, "Write 7 random bytes to UART TX");

-- It is recommended to use constants to improve the readability of the code, e.g.:
sbi_write(SBI_VVCT, 0, C_ADDR_UART_BAUDRATE, C_BAUDRATE_9600, "Set UART baud rate to 9600");

sbi_read()

Adds a read command to the SBI 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 sbi_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 SBI VVC dedicated scoreboard where it will be checked against the expected value (provided by the testbench).

sbi_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 a SW accessible register. Could be offset or full address depending on the DUT.
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:
sbi_read(SBI_VVCT, 0, x"1000", "Read UART baud rate", C_SCOPE);
sbi_read(SBI_VVCT, 0, x"1002", TO_SB, "Read UART RX and send to Scoreboard", C_SCOPE);

-- It is recommended to use constants to improve the readability of the code, e.g.:
sbi_read(SBI_VVCT, 0, C_ADDR_UART_BAUDRATE, "Read UART baud rate");

-- 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.
...
sbi_read(SBI_VVCT, 0, C_ADDR_UART_BAUDRATE, "Read from Peripheral 1");
v_cmd_idx := get_last_received_cmd_idx(SBI_VVCT, 0);
await_completion(SBI_VVCT, 0, v_cmd_idx, 1 us, "Wait for read to finish");
fetch_result(SBI_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.

sbi_check()

Adds a check command to the SBI 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 sbi_check() procedure. The sbi_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.

sbi_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 a SW accessible register. Could be offset or full address depending on the DUT.
constant	data	in	std_logic_vector	The expected data value to be read from 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:
sbi_check(SBI_VVCT, 0, x"1155", x"3B", "Check data from UART RX");
sbi_check(SBI_VVCT, 0, x"1155", x"3B", "Check data from UART RX", TB_ERROR, C_SCOPE):

-- It is recommended to use constants to improve the readability of the code, e.g.:
sbi_check(SBI_VVCT, 0, C_ADDR_UART_RX, C_UART_START_BYTE, "Check data from UART RX");

sbi_poll_until()

Adds a poll_until command to the SBI 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 sbi_poll_until() procedure. The sbi_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.

sbi_poll_until(VVCT, vvc_instance_idx, addr, data, 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 address of a SW accessible register. Could be offset or full address depending on the DUT.
constant	data	in	std_logic_vector	The expected data value to be read from the addressed register
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.

-- Examples:
sbi_poll_until(SBI_VVCT, 0, x"1155", x"0D", "Read UART RX until CR is found");
sbi_poll_until(SBI_VVCT, 0, x"1155", x"0D", "Read UART RX until CR is found", 5, 0 ns, TB_WARNING, C_SCOPE);

-- It is recommended to use constants to improve the readability of the code, e.g.:
sbi_poll_until(SBI_VVCT, 0, C_ADDR_UART_RX, C_CR_BYTE, "Read UART RX until CR 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.

SBI transaction info record fields. Transaction Type: t_base_transaction (BT) - accessible via shared_sbi_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 SBI read or write transaction
data	std_logic_vector(31 downto 0)	0x0	Data for SBI 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

SBI transaction info record fields. Transaction type: t_compound_transaction (CT) - accessible via shared_sbi_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 SBI read or write transaction
data	std_logic_vector(31 downto 0)	0x0	Data for SBI read or write transaction
randomisation	t_randomisation	NA	sbi_write() will generate random data when set to RANDOM
num_words	natural	1	Use with randomization to write a number of random words using a single sbi_write() command
max_polls	integer	1	Maximum number of polls allowed in the sbi_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. sbi_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 SBI scoreboard is accessible from the testbench as a shared variable SBI_VVC_SB, located in the vvc_methods_pkg.vhd, e.g.

SBI_VVC_SB.add_expected(C_SBI_VVC_IDX, pad_sbi_sb(v_expected), "Adding expected");

The SBI 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_sbi_sb() function, e.g.

SBI_VVC_SB.add_expected(<SBI VVC instance number>, pad_sbi_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 SBI VVC scoreboard using the SBI_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_sbi_vvc_config(C_VVC_INDEX).unwanted_activity_severity := NO_ALERT;

Note that the ready signal is not monitored in this VVC. When the ready signal is in use, i.e. sbi_bfm_config.use_ready_signal := true, the ready signal is allowed to be set independently of the enable signal (wena, rena), and there is no method to differentiate between the unwanted activity and intended activity. When the ready signal is not in use, i.e. sbi_bfm_config.use_ready_signal := false, the ready signal holds its level high. See SBI protocol for more information on the ready signal.

For SBI 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 SBI 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

• SBI BFM

Before compiling the SBI 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 SBI VVC

Compile to library	File	Comment
bitvis_vip_sbi	sbi_bfm_pkg.vhd	SBI BFM
bitvis_vip_sbi	transaction_pkg.vhd	SBI transaction package with DTT types, constants, etc.
bitvis_vip_sbi	vvc_cmd_pkg.vhd	SBI VVC command types and operations
bitvis_vip_sbi	../uvvm_vvc_framework/src_target_dependent/td_target_support_pkg.vhd	UVVM VVC target support package, compiled into this VVC library
bitvis_vip_sbi	../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_sbi	vvc_sb_pkg.vhd	SBI VVC scoreboard
bitvis_vip_sbi	vvc_methods_pkg.vhd	SBI VVC methods
bitvis_vip_sbi	../uvvm_vvc_framework/src_target_dependent/td_queue_pkg.vhd	UVVM queue package for this VVC
bitvis_vip_sbi	../uvvm_vvc_framework/src_target_dependent/td_vvc_entity_support_pkg.vhd	UVVM VVC entity support compiled into this VVC library
bitvis_vip_sbi	sbi_vvc.vhd	SBI VVC
bitvis_vip_sbi	vvc_context.vhd	SBI 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 additional documentation on the SBI protocol, please see SBI protocol.

Important

• This is a simplified Verification IP (VIP) for SBI.

• The given VIP complies with the basic SBI protocol and thus allows a normal access towards a SBI interface.

• This VIP is not a SBI 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.

Footnotes

[1]

https://www.aldec.com/en/support/resources/multimedia/webinars/1673