Does the A7’s SDRAM Controller Support any 32-bit-wide (x32) SDRAM Devices?

The following information is based on customer reports.  This information is preliminary and has not been fully verified by Triscend in an actual system.  Consequently, this solution may contain errors.  Use this information at your own risk.

The embedded SDRAM controller on the Triscend A7S20 device supports 8-bit, 16-bit, or 32-bit SDRAM memory subsystems, built using 8-bit (x8) or 16-bit (x16) SDRAM devices.  It was not designed to support 32-bit (x32) SDRAM devices.

However, as luck would have it, some Triscend A7 customers have reported success using the 64Mbit, 32-bit wide SDRAM devices from Micron Technology, part number MT48LC2M32.  Typically, x32 SDRAM devices tend to be more expensive than their x8 or x16 cousins.  However, because these x32 devices represent a single-chip SDRAM subsystem, they use less board space, which is more important than cost in some systems.

The following steps describe how to connect the A7S20 to a Micron MT48LC2M32 x32 SDRAM device.

Connect the A7S20 to a MT48LC2M32B2 SDRAM

Figure 1.  Connections between a A7S20 and MT48LC2M32 SDRAM.

Figure 1 shows the connections between a Triscend A7S20 and a Micron Technology MT48LC2M32BS SDRAM device.  The A7’s Memory Sub-System Interface Unit (MSSIU) supports both SDRAM and Flash.  The connections to Flash are not shown here, for clarity’s sake.

The SDRAM row and column addressing appears on the A7’s A[17:8] address lines.  Other SDRAM control signals such as RAS#, CAS#, and bank select appear on the A7’s A[6:0] address lines.

Configure the A7’s MSSIU SDRAM Settings in FastChip

Choose Constraints à I/O Editor from the FastChip menu to launch the I/O Editor.  Click MIU in the I/O Editor tool bar.

Configure SDRAM Controller for Single 2Mx32 Device

Click the SDRAM Memory tab.  Choose 1 external SDRAM bank.  Select a 2Mx32 SDRAM memory subsystem.  The Micron 64Mbit, x32 device is effectively an entire 2Mx32 memory subsystem, implemented in a single SDRAM component.

Click OK.

Bind the A7S20 Design

Click Bind in the FastChip tool bar.

Copy the Memory Registry File

Before creating a configuration image, FastChip must know about this new Micron 64Mbit, x32 SDRAM.

Extract the sdram_micron_MT48LC2M32.zip file attached to this article into the following FastChip directory.  The directory path assumes that FastChip was installed in the default location.

C:\Triscend\FastChip\Data\MemoryRegistry

Create a Configuration Image

Once Bind successfully completes, create a new configuration image. Click Device Link in the FastChip tool bar to invoke FastChip Device Link (FDL).  Once FDL appears on the screen, click Configuration.

Select the Desired SDRAM Part

Configure the SDRAM settings for the desired Micron 64Mbit, x32 SDRAM device.  In the Configuration dialog box, select the dropdown arrow to reveal the supported SDRAM part.  Select one of the supported MT48LC2M32 devices from the list, including the SDRAM speed grade.

After selecting all your Configuration options, click OK.

FastChip Version: 2.3.0

This solution may or may not apply to other versions of the FastChip development system.

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