The PCMCIA standard gives a desirable interface for sharing resources between a host and co-processor. In this general purpose implementation, a Texas Instruments TMS320C51 fixed-point DSP has been interfaced to the PCMCIA bus using a TPC1280 FPGA. The DSP is able to run at 40 MIPs with zero wait-state SRAM that the host PC is also able to share and may be mapped directly into the x86 memory map using PCMCIA Card Services. The host PC may download DSP code directly into the DSP's SRAM and initiate DSP operation.
Two memory models have been imple-mented here: a slower single-data modem model and faster block-data sound card model. The two processors are also able to share some FLASH EEPROM that is used for the PCMCIA CIS or DSP boot-loading. Serial and parallel expansion give the ability for varied analog interfaces.
In this diagram, the PCMCIA connector appears on the left side of the board. The FPGA/ASIC integrates all parts of the system; it is the system traffic cop. On the right side of the FPGA/ASIC is a second bus that connects to the memories, DSP and any other peripherals that can be chosen to be placed there (such as a parallel stereo codec). There is an analog front-end board connector that has been defined and placed on the other side of the board for external serial and slow I/O interface such as modem or scanner port.
June 1996, vol. 13, no. 4
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