Altera Mentor Verification IP Altera Edition AMBA AXI4-Lite - Manual (Page 148)

Mentor Verification IP AE AXI4-Lite User Guide, V10.3 148
VHDL API Overview
Operational Transaction Fields
April 2014
Handshake Delay
The delay between the *VALID and *READY handshake signals for each of the five protocol
channels is controlled in a BFM test program using execute_*_ready(), get_*_ready() and
get_*_cycle() procedures. The execute_*_ready() procedures place a value onto the *READY
signals, and the get_*_ready() procedures retrieve a value from the *READY signals. The
get_*_cycle() procedures wait for a *VALID signal to be asserted and are used to insert a delay
between the *VALID and *READY signals in the BFM test program.
For example, the master BFM test program code below inserts a specified delay between the
read channel RVALID and RREADY handshake signals using the execute_read_data_ready()
and get_read_data_cycle() procedures.
-- Set the RREADY signal to ‘0’.
execute_read_data_ready(0, 1, bfm_index, AXI4_PATH_6,
axi4_tr_if_6(bfm_index));
-- Wait for the RVALID signal to be asserted.
get_read_data_cycle(bfm_index, AXI4_PATH_6,
axi4_tr_if_6(bfm_index));
-- Add delay between RVALID and RREADY.
for i in 0 to 2 loop
wait_on(AXI4_CLOCK_POSEDGE, bfm_index, AXI4_PATH_6,
axi4_tr_if_6(bfm_index));
end loop;
execute_read_data_ready(1, 1, bfm_index, AXI4_PATH_6,
axi4_tr_if_6(bfm_index));
In this example, the bfm_index specifies the BFM.
*VALID Signal Delay Transaction Fields
The transaction record contains a *_valid_delay transaction field for each of the five protocol
channels to configure the delay value prior to the assertion of the *VALID signal for the
channel. The master BFM holds the delay configuration for the *VALID signals that it asserts,
and the slave BFM holds the delay configuration for the *VALID signals that it asserts.
Table 7-2 specifies which *_valid_delay fields are configured by the master and slave BFMs.
Table 7-2. Master and Slave *_valid_delay Configuration Fields
Signal Operational Transaction Field Configuration BFM
AWVALID address_valid_delay Master
WVALID data_valid_delay Master
BVALID write_response_valid_delay Slave
ARVALID address_valid_delay Master
RVALID data_valid_delay Slave