On 11/16/2019 06:56 PM, W2HX via cctalk wrote:
Is the BBB not fast enough to do Qbus? Meaning, for qbus, would a FPGA be 
necessary? Or was this just the op's choice among many possible options?


The PRU on the Beagle Bone Black is pair of 200 MHz 32-bit microcontrollers which can do all sorts of I/O tasks. There is a limit on the number of direct I/O lines available, however, so that may not be so simple. I've used them for 8-bit ports, plus a few control lines, and that all worked great. There is a bit more latency if you need to use non-direct GPIO pins to the PRU, but they still are pretty fast.

The PRU has direct, 5ns access to a limited amount of shared memory, but can access the ARM CPU's memory with some additional delay. So, I think you could probably do a Q-bus, but might have to go through some contortions to get enough I/O pins and memory for larger transfers.

Jon

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