Extending an 8-bit architecture

-- EDN, 2/17/2000

Waferscale Integration returns to its 8-bit microcontroller-peripheral roots with the EasyFlash PSD9XX family, which forgoes the integrated complex PLD of previous-generation PSD8XX devices but offers a simpler development- and programming-tool environment (Picture). On-chip primary-flash-memory-partition options range from 1 to 2 Mbits, and you can use a secondary 256-kbit EEPROM or flash-memory array for system boot code or in-system-reprogramming of the primary flash-memory array. A 16- or 64-kbit, battery-backed SRAM completes the embedded-memory smorgasbord.

PSD9XX chips retain sufficient programmable logic to enable you to customize them for a variety of microcontroller interfaces and to re-create I/O pins lost to address and data buses, to decode incoming accesses, and to generate external chip selects to other peripherals if necessary. The free PSDSoft Express design software, downloadable from the vendor's Web site, incorporates a point-and-click menu-based interface that requires no HDL or schematic expertise, and the $99 DK900 development kit includes an evaluation board and a JTAG programmer. Packaging options include 52- and 64-pin PLCC and 64-pin TQFP; Table 1 gives device specifications and prices.

Waferscale Integration, 1-510-656-5400.

-by Brian Dipert