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Hi,
I am trying to do memory test on all RAM memory spaces on LPC2148. Till the end of static RAM 0x40007FFF there is no problem. But when I try to access and write (Base Address=7FD00000H)USB DMA RAM getting error on console and it enters infinite loop. Data Abort: ARM Instruction at 00000070H, Memory Access at 7FD00000H
But in manual it says "While the USB DMA is the primary user of the additional 8 kB RAM, this RAM is also accessible at any time by the CPU as a general purpose RAM for data and code storage."
Thanks for answers.
Arjun
Have you powered it up?
Remember that the special memory blocks are part of peripherials, and the peripherials can be powered up/down.
By powering up did you meant connecting to DC supply ? I have connected to USB power source from laptop blinky and LCD programs ran fine.
I am using NGX Technologies blueboard.
I believe Per was talking about:
Table 31. Power Control for Peripherals register (PCONP - address 0xE01F C0C4) bit description
Bit-31 -> PUSB -> USB power/clock control bit. This bit must be set to one to access the 8 kB USB RAM at location 0x7FD0 0000 (see Figure 2).
hi,
As he said I tried to set PUSB bit in PCONP Power Control for Peripherals Register at startup.s PCONP EQU 0x801817BE.
But I read it in manual in section "Prefetch abort and data abort exceptions" here they have clearly said that system generates the appropriate bus cycle abort exception if an access is attempted for an address that is in a reserved or unassigned address region.
Is there any work around for this?
Forgive me if I am wrong. I am beginner.