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
