Hi everyone,
I’m developing an industrial control board based on the Intel i960 NG80960JD3V66 (32-bit RISC, 66MHz, 132-QFP package). During hardware debugging, I’ve run into a few issues and would appreciate advice from anyone with experience:
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Clock Configuration
The datasheet mentions an external clock source but doesn’t clarify whether PLL multiplication is supported. My current design uses a 33MHz crystal, hoping to generate 66MHz via internal PLL:-
Is there a specific register that needs to be configured to enable the PLL?
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Are there any known clock jitter limits?
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Interrupt Controller
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Is interrupt priority fixed in the i960 JD series (e.g., IRQ0 highest)?
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In RISC mode, what’s the typical interrupt latency? The datasheet only states “≤10 cycles,” but my tests show ~15 cycles (no cache hits).
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Unused Pin Handling
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The 132-QFP package has several reserved pins (e.g.,
RSVD1-4), and the datasheet recommends “leave floating.” But in a high-noise environment, should they be pulled up/down?
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Additional Info:
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Toolchain: Green Hills MULTI 4.1.5 (legacy version with i960 support).
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Hardware: Custom 4-layer PCB, power supply noise <50mVpp.
Attempted Solutions:
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Directly connected 33MHz crystal to
CLKIN—core fails to start. -
Interrupt latency test code (based on manual examples), results are inconsistent.
Has anyone worked with this legacy MPU? Or know where to find more detailed app notes?
