I am told to design a generic microprocessor interface for a ASIC chip. Since I am not familiar with what types/modes of microprocessor are most popular, I don't know how generic I can reach.
I am aware of there are synchronous/asychronous modes, separate or mux address/data modes. But I notice there are so many different families and series. Would somebody point me some typical families of Microprocessor or even its datasheet?
Thanks,
Most embedded processors will interface to peripherals that look like old-style asynchronous generic RAM like the 6164 or 6264 (I'm dating myself here).
Chip select, active low. Read, active low. Write, active low. Separate address and data buses -- as many bits as you need.
Write to the chip happens on the trailing (positive) edge of the write pulse or the CS pulse, whichever goes away first. Read from the chip happens for as long as read and CS are low.
Anything more specific should be preceded by a thorough survey of the microprocessors you intend to interface to.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com
How fast? Most microprocessors and microcontrollers have an SPI interface. Where I used to work we used SPI to interface to our ASIC, and an FPGA.
Leon
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I think you need to decide on the width of the bus. Is it 8 bit, 16 bit and/or 32 bit.
Address Data Chip Select
For 8 bit data /RD Read Strobe /WR Write strobe
For 16 bit buses, you have typically have two options
1) Byte Lane Enables /RD /WR /BHE Byte High Enable /BLE Byte Low EnableThe latter two determine if the upper and/or lower byte is affected by the access.
2) Word Read/Byte Write /RD Read /WRH Write High Byte Lane /WRL Write Low Byte LaneFor 32 bit buses, the byte lane method is most common.
Sometime you want to add waitstates, and the wait signal needs to be either active low or active high.
The MC68000 is a pretty strange beast, but it is more or less obsolete. Maybe the Coldfire has the same, never checked.
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