ssubrama@pyrps5.pyramid.com (R.Sankar) (04/11/90)
My friend is facing a problem with sun4/330. He is going in circles with this problem. Can anybody help him out? The problem as told by him is We have got a SUN 4/330 Sparc machine. We are trying to add a new controller (Terminal controller) card on the VME bus. We are facing a problem with the SUN VME BUS Arbiter. The problem is as follows: 1. Controller Requests for bus 2. Controller gets the bus 3. Controller does the transaction on the bus 4. CPU Requests for the bus before the last transaction is over 5. Controller Releases the bus after the last transaction 6. CPU asserts BBSY* 7. CPU negates the Bus Request after 40ns 8. But CPU Negates the BBSY* after 100ns from the time it is asserted 9. Bus Arbiter asserts BG , 100ns after BBSY* is negated 10. Controller gets BGIN* 11. Controller passes BGOUT* (because controller didn't request the bus) 12. Arbiter waits for BBSY* assertion. 13. System crashes with BUS ERROR (TIME OUT) message. Timing diagram follows. - -------------------------------------------------------- CBR* | | ---- VBR* -- -------------------------- -------------------- | | | | ---- --------- BGIN* ---- ---------------------------------------------- | | | ---- --------- BGOUT* --------------------------------------------------------- | -------- BBSY* ------- --- ----------------- | | | | ------------------------------- ---- <--Controller transactionr--> <--CPU transaction causing hang condition--> Please pass on any info to ssubrama@pyrps5.pyramid.com Thanks