Altera RapidIO MegaCore Function Manuale Utente Scaricare il pdf (Pagina 170)

7–8 Chapter 7: Testbenches

RapidIO MegaCore Function August 2014 Altera Corporation

User Guide

NREAD Transactions

The next set of transactions tested are

NREAD

s. The DUT sends a group of

NREAD

transactions to the sister_rio module by cycling the read burst size from 8 to

MAX_READ_BYTES

in increments of 8 bytes. For each iteration, the

rw_addr_data

task is

called. This task is defined in the bfm_io_read_master instance of the Avalon-MM

master BFM. The task performs the read request packets across the I/O Avalon-MM

Slave Read interface. The read transaction across the Avalon-MM interface is

translated into a RapidIO

NREAD

request packets. The values of the

rd_address

rd_byteenable

, and

rd_burstcount

parameters determine the values for the

rdsize

wdptr

and

xamsbs

fields in the header of the RapidIO packet.

The

NREAD

request packets are received by the DUT and are translated into

Avalon-MM read transactions that are presented across the sister_rio module‘s I/O

master Avalon-MM interface. An instance of avalon_bfm_slave, the BFM for an

Avalon-MM slave, is driven by this interface. The read operations are checked and

data is returned by calling the task,

write_readdata

. This task drives the

data

and

read

datavalid

control signals on the Avalon-MM master read port of the DUT.

The returned data is expected at the DUT’s I/O Avalon-MM slave interface. The

rw_data

task is called and it captures the read data. This task is defined inside the

instance of bfm_io_read_master. The read data and the expected value are then

compared to ensure that they are equal.

Doorbell Transactions

To test

DOORBELL

messages, the

doorbell

interrupts must be enabled. To enable

interrupts, the testbench sets the lower three bits in the

Doorbell

Interrupt

Enable

0x0000_0020

. The test also programs the DUT to store all of

the successful and unsuccessful

DOORBELL

messages in the Tx Completion FIFO.

For more information, refer to Table 6–65 on page 6–29.

Next, the test pushes eight

DOORBELL

messages to the transmit

DOORBELL

Message FIFO

of the DUT. The test increments the message payload for each transaction, which

occurs when the

rw_addr_data

task (defined in the bfm_drbell_s_master instance) is

invoked with a

‘WRITE

operation to the

doorbell

0x0000_000C

This action programs the 16-bit message, an incrementing payload in this example, as

well as the

DESTINATION_ID

—

0x55

for an 8-bit device ID or

0x5555

for a 16-bit device

ID—which is used in the

DOORBELL

transaction packet.

To verify that the

DOORBELL

request packets have been sent, the test waits for the

drbell_s_irq

signal to be asserted. The test then reads the

Doorbell

Completion

DOORBELL

messages that have been added to the Tx Completion FIFO. Eight successfully

completed

DOORBELL

messages should appear in that FIFO and each one should be

accessible by reading the

Tx Doorbell

Completion

To perform this verification, the test invokes the

rw_data

task defined in the instance

bfm_drbell_s_master.

If you created the DUT with Doorbell Rx enable turned on and with Doorbell Tx

enable turned off, the doorbell test programs the sister_rio module to send eight

DOORBELL

messages to the DUT. The test verifies that all eight

DOORBELL

messages were

received by the DUT. The test calls the

rw_addr_data

task defined in the instance

sister_bfm_drbell_s_master. The task performs a write to the

Doorbell

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