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12409 Discussions

Nios2 and external Microcontroller together access a SDRAM

Altera_Forum
Honored Contributor II
968 Views

Hi all, 

 

My system consists of a microcontroller (TI Concerto Cortex M3) 

and a FPGA (altera cyclon IV E) and a SDRAM. 

The microcontroller connects only with FPGA(Address / data / control signals). The SDRAM is connected directly with the FPGA. 

 

I plan to: 

A portion of the SDRAM is reserved for Nios2 (Data and 

Instructionmemory), the remainder of the SDRAM 

is for the Microcontroller (Concerto). 

 

My question is, how can i achieve this? 

 

In this case i have 2 Avalon MM Masters, Nios2 (higher priority) and the external Microcontroller (lower priority), both access the SDRAM over SDRAM Controller IP. Which solution is the best for me? 

 

Thanks in advance! 

Tomy
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2 Replies
Altera_Forum
Honored Contributor II
77 Views

Leave the bus arbitration for the subsystem itself - it will do it automatically. However I hope You don't need speed, since sharing a memory bus slows down the system because of many wait requests...

Altera_Forum
Honored Contributor II
77 Views

Hi Socrates, 

 

many thanks for your reply!:-) 

 

My Nios2 runs at 75Mhz, but this is not fixed. 

Is there an other solution besides the Avalon MM Master for me? Cant i tell the Qsys, let Nios2 higher priority, so that the Microcontroller must wait until ther Nios2 is done with SDR-SDRAM? 

 

thanks in advance! 

Tomy 

ps. sorry for my english!:(
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