Intel® Quartus® Prime Standard Edition User Guide: Platform Designer

ID 683364
Date 12/15/2018
Public
Document Table of Contents

3.1.10. Waitrequest Allowance Adapter

The Waitrequest Allowance Adapter allows a connection between a master and a slave interface with different waitrequestAllowance properties.

The Waitrequest Allowance adapter provides the following features:

  • The adapter is used in the memory-mapped domain and operates with signals on the memory-mapped interface.
  • Signal widths and all properties other than waitrequestAllowance are identical on master and slave interfaces.
  • The adapter does not modify any command properties such as data width, burst type, or burst count.
  • The adapter is inserted by the Platform Designer interconnect software when a master and slave with different waitrequestAllowance property are connected.

When the slave has a waitrequestAllowance = n the master must deassert read or write signals after <n> transfers when waitrequest is asserted.

Table 28.  Interconnect Scenarios Requiring waitrequestAllowance
Master (m) / Slave (n) waitrequestAllowance Adaptation Required Description Adapter Function
m = n No

The master waitrequestAllowance is equal to the slave's waitrequestAllowance.

All signals are passed through.

m = 0; n > 0 Yes

The master cannot send when waitrequest=1, but holds the value on the bus. This would result in the slave receiving multiple copies.

Requires adaptation to prevent.

The adapter deasserts valid when input waitrequest is asserted.
m < n; m != 0 No

The master can send <m> transfers after waitrequest is asserted. The slave receives fewer than <n> transfers, which is acceptable.

All signals are passed through.
m > n; n = 0 Yes

The slave cannot accept transfers when waitrequest is asserted. Transfers sent when waitrequest=1 can be lost.

Prevention requires adaptation in the form of transfer buffering.

If the input waitrequest is asserted, the adapter buffers the input data.
m > n; n > 0 Yes

The slave cannot accept more than <n> transfers after waitrequest is asserted, however the master can send up to <m> transfers.

Transfers ( <m><n>) can be lost.

Prevention requires adaptation in the form of transfer buffering.

The adapter buffers the input data.