hi all shared memory querry
Started by ●March 28, 2005
Hi all,
I am working on the ADSP-21160 board, I have one PCIDSP board in which 3 ADSP-21160 are embedded,there is host communication to this processors via a PCI bus, so my input is comming through the PCI bus and is stored in the internal memory.
I have a memory SDRAM of 64MB.
1. My question is how i can make this external memory 64MB as a shared memory to all the 3 processors,presently this SDRAM memory is mapped to 0x1800000 address.
2. IS there any best method so that i can transfer my input the external memory. easilly becouse i have the data of 60MB to operate.
Please help me in this regards,
Thanks
Harsha S
Reply by ●March 28, 20052005-03-28
On Sun, 28 Mar 2005, harsha sb sb wrote:
> I am working on the ADSP-21160 board, I have one PCIDSP board in which 3 ADSP-21160 are embedded,there is host communication to this processors via a PCI bus, so my input is comming through the PCI bus and is stored in the internal memory.
> I have a memory SDRAM of 64MB.
> 1. My question is how i can make this external memory 64MB as a shared memory to all the 3 processors,presently this SDRAM memory is mapped to 0x1800000 address.
> 2. IS there any best method so that i can transfer my input the external memory. easilly becouse i have the data of 60MB to operate.
Hello Harsha,
The problem with allowing all processors access to the same memory is bus
contention. You have to ensure that only one processor has the bus at a
time. You can do that by using the built in br (bus request) lines. You
can do it with a CPLD that prevents bus access by multiple devices using
the ack line to insert wait states. You could get really fancy and use
dual ported ram and an fpga so each processor doesn't see the sdram as a
bottle neck too, but that gets really expensive and time consuming.
Look at the system architecture chapter in the 21160 manual. It will give
you lots of good ideas.
Patience, persistence, truth,
Dr. mike
> I am working on the ADSP-21160 board, I have one PCIDSP board in which 3 ADSP-21160 are embedded,there is host communication to this processors via a PCI bus, so my input is comming through the PCI bus and is stored in the internal memory.
> I have a memory SDRAM of 64MB.
> 1. My question is how i can make this external memory 64MB as a shared memory to all the 3 processors,presently this SDRAM memory is mapped to 0x1800000 address.
> 2. IS there any best method so that i can transfer my input the external memory. easilly becouse i have the data of 60MB to operate.
Hello Harsha,
The problem with allowing all processors access to the same memory is bus
contention. You have to ensure that only one processor has the bus at a
time. You can do that by using the built in br (bus request) lines. You
can do it with a CPLD that prevents bus access by multiple devices using
the ack line to insert wait states. You could get really fancy and use
dual ported ram and an fpga so each processor doesn't see the sdram as a
bottle neck too, but that gets really expensive and time consuming.
Look at the system architecture chapter in the 21160 manual. It will give
you lots of good ideas.
Patience, persistence, truth,
Dr. mike
