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

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

4.3. Tri-State Components

The tri-state interface type allows you to design Platform Designer subsystems that connect to tri-state devices on your PCB. You can use tri-state components to implement pin sharing, convert between unidirectional and bidirectional signals, and create tri-state controllers for devices whose interfaces can be described using the tri-state signal types.

Tri-State Conduit System to Control Off-Chip SRAM and Flash Devices

In this example, there are two generic Tri-State Conduit Controllers. The first is customized to control a flash memory. The second is customized to control an off-chip SSRAM. The Tri-State Conduit Pin Sharer multiplexes between these two controllers, and the Tri-State Conduit Bridge converts between an on-chip encoding of tri-state signals and true bidirectional signals. By default, the Tri-State Conduit Pin Sharer and Tri-State Conduit Bridge present byte addresses. Typically, each address location contains more than one byte of data.

Figure 131. Tri-State Conduit System to Control Off-Chip SRAM and Flash Devices

Address Connections from Platform Designer System to PCB

The flash device operates on 16‑bit words and must ignore the least‑significant bit of the Avalon-MM address. The figure shows addr[0]as not connected. The SSRAM memory operates on 32-bit words and must ignore the two low-order memory bits. Because neither device requires a byte address, addr[0] is not routed on the PCB.

The flash device responds to address range 0 MB to 8 MB-1. The SSRAM responds to address range 8 MB to 10 MB-1. The PCB schematic for the PCB connects addr[21:0] to addr[18:0] of the SSRAM device because the SSRAM responds to 32‑bit word address. The 8 MB flash device accesses 16‑bit words; consequently, the schematic does not connect addr[0]. The chipselect signals select between the two devices.

Figure 132. Address Connections from Platform Designer System to PCB
Note: If you create a custom tri-state conduit master with word aligned addresses, the Tri‑state Conduit Pin Sharer does not change or align the address signals.
Figure 133. Tri-State Conduit System in Platform Designer