Altera Avalon Verification IP Suite - Manual (Page 134)

3–2 Chapter 3: External Memory BFM
Functional Description
Avalon Verification IP Suite User Guide May 2011 Altera Corporation
Table 3–2 lists the function of the external memory BFM and its related components.
f For more information about tristate conduit bridge, refer to “Tristate Conduit Bridge”
section in the
Qsys Interconnect chapter of the Quartus II Handbook.
For more information about tristate conduit pin sharer, refer to “Tristate Conduit Pin
Sharer” section in the
Qsys Interconnect chapter of the Quartus II Handbook.
For more information about generic tristate controller, refer to “Generic Tristate
Controller” section in the
Qsys Interconnect chapter of the Quartus II Handbook.
Initializing the Memory Content
At the beginning of the simulation, the external memory BFM loads the memory
initialization file (
INIT_FILE ) to initialize its memory content. For example, if the
memory file has a memory size of 50, the BFM fills its memory content with addresses
0–49. However, if you do not provide the memory initialization file, the memory
content of the BFM remains blank.
Reading and Writing to the Memory Content
You can read or write to the memory content through the APIs or the interface signals.
Reading from the Memory
The BFM uses cdt_data_io as a bidirectional data port. During read transfers, this
port acts as an output port and drives the corresponding address memory content
when the BFM asserts or deasserts the following signals:
■ Asserts cdt_output_enable signal
■ Asserts cdt_read signal
■ Deasserts cdt_write signal
■ Asserts cdt_chip_select signal
Otherwise, the cdt_data_io port acts as an inactive input port and is held in high
impedance state.
Table 3–1. External Memory BFM and Related Components
Component Description
External memory BFM
Represents the external RAM. The external memory BFM is a
memory model with an Avalon-TC interface. The BFM also models a
set of memories that are supported by the generic tristate controller
component.
Tristate Conduit Bridge Converts Avalon-TC signals into conduit signals.
Tristate Conduit Pin Sharer
Carries the shared address bus and data. Tristate Conduit Inverse Pin
Sharer
Generic Tristate Controller
Controls the external memory BFM. The generic tristate controller
accepts read and write requests and converts these requests into
necessary SDRAM and bank management commands.