Concurrent flash and programmable logic for 16/32 bit MCUs and DSPs

DSP, Micros & Memory

9 May 2001 DSP, Micros & Memory

STMicroelectronics has introduced a new family of ultra low-power programmable system devices (PSDs) that provide 100% in-system programmable concurrent flash memory, SRAM, programmable logic, and extra I/O for 16 and 32 bit microcontrollers from major vendors, such as Motorola, Intel, Hitachi, Infineon and Philips, as well as DSPs from Texas Instruments and Analog Devices. According to ST many of these 16 bit controllers have no flash memory and those that do are limited to 128 KB.

Two devices are being introduced, the PSD4135G2 and the PSD4235G2. Both have 512 KB flash, a second concurrent 32 KB flash array, 8 KB of SRAM, a built-in configurable interface for 16 bit and 32 bit MCUs or DSPs, a programmable address decoder, and a small CPLD for chip selects, combinatorial logic and configurable pin-assignments.

The PSD4235G2 also has additional sequential logic in a 3000 gate general purpose CPLD. With 82 inputs and 24 outputs, the CPLD provides enough on-chip programmable logic to implement peripheral functions, such as shift registers, mail boxes, and serial channels. The PSD4235G2 also allows JTAG chaining during in-system programming. New PSD4000 Series devices will be added soon that expand the flash memory to 8 and 16 MB, and increase the SRAM to 256 Kb and 1 Mb.

An ISP JTAG port on PSD4000 devices can be used to program the entire device including memory, CPLD, and configuration logic in as little as twenty seconds, says STMicroelectronics, using its FlashLink programmer. Other solutions including single chip MCUs and convention flash memories require boot code in the system to perform the programming sequence.

PSD4000 devices are ideal for any high-performance embedded control systems that have large code and data storage requirements, such as controllers for voice processing, high capacity tape drives, fibre-optic lasers, and framer/router background controllers. Since they are 'in-application programmable' (IAP), they can be re-programmed remotely, without affecting system operation.

EDA tools support

STMicroelectronics' free PSDsoft Express EDA tool automatically generates the HDL for the MCU/DSP interface, address decoding, paging, segmentation, chip selects, and pin assignments for PSD4000 devices. For designers who want to use the PSD4235G2 general purpose CPLD to design custom peripherals with sequential logic, ST provides its PSDsoft 2000 EDA tool.

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Concurrent flash and programmable logic for 16/32 bit MCUs and DSPs

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