I have a board that has VME64 core implemented in it and this board communicates with other boards via VME64 bus. All boards share the same backplane motherboard which has J1, J2 connectors on it.
If the following pins on the board are connected as follows:
BG0IN is directly connected with BG0OUT (onboard).
BG1IN is directly connected with BG1OUT (onboard).
BG2IN is directly connected with BG2OUT (onboard).
BG3IN is directly connected with BG3OUT (onboard).
BR0 to BR3: no connection.
IRQ1 to IRQ7: No connection.
I could not understand how will the bus arbitration work if the above pins connections are in place on the board? Is it some fix mode for 'Bus master' or 'Remote terminal' mode?
Best Answer
If a VME card never requests the bus, it would not need to monitor or control the bus-grant daisy-chain.
Thus in that case it can always pass BGin direct to BGout.
A card with only memory or peripherals would be such a card.