Modules Deliver Smart Memory

Flash memory is the dominant non-volatile storage for embedded applications. Often, though, it's simply a bank of memory that requires a custom interface providing only storage support. PQI and M-Systems offer two very different intelligent modules that bring NAND flash functionality to embedded systems using standard interfaces.

The PQI DiskOnModule is part of a line of flash-memory products that encapsulate flash memory into an intelligent device. In this case, it looks like a standard 40-pin ATA drive interface. Figure 1 shows a version that plugs directly onto a header like that found on most motherboards and single-board computers (SBCs). I was able to program a DiskOnModule using a standard PC motherboard and then move it to an SBC for development.

The DiskOnModule comes in sizes up to 1 Gbyte. It consumes under 28 mA when writing and only 0.3 mA during sleep mode. It has a read transfer rate of 4.1 Mbytes/s. Prices start at under $100, and a variety of other form factors are also available.

The DiskOnChip modules from M-Systems can be found on a wide range of standard SBCs and embedded products. The latest incarnation, the mDiskOnChip G3, targets mobile devices like cell phones, small cameras, and multimedia devices.

The mDiskOnChip G3 employs the company's x2 technology along with error detection and correction support (Fig. 2). The chip supports eXecute In Place (XIP) boot block, which mirrors flash in on-chip SRAM. Versions are available with up to 128 Mbytes of flash. Pricing for 64 Mbytes is $25.