The 0x4000 bytes of ethernet ram @ 0x7FD00000 can be used for the LCD frame
buffer (if it is enough). There is no need to enable the ethernet to access this
ram.
I have not been able to use the 0x4000 bytes of AHB1 ram @ 0x7FE00000 for the
LCD frame buffer. I can read and write to it from the debugger, but the LCD is a
no go. It does not seem to matter if the USB is enabled or not. I thought I saw
a post describing this. Has this been done?
LPC247x - using USB or Ethernet ram as LCD frame buffer
Started by ●August 29, 2009
Reply by ●August 29, 20092009-08-29
I don't know how to awnser you question, but, did you changed the .ld
file
to match your new RAM config ?
2009/8/29 tclarke1
> The 0x4000 bytes of ethernet ram @ 0x7FD00000 can be used for the LCD frame
> buffer (if it is enough). There is no need to enable the ethernet to access
> this ram.
>
> I have not been able to use the 0x4000 bytes of AHB1 ram @ 0x7FE00000 for
> the LCD frame buffer. I can read and write to it from the debugger, but the
> LCD is a no go. It does not seem to matter if the USB is enabled or not. I
> thought I saw a post describing this. Has this been done?
>
>
>
to match your new RAM config ?
2009/8/29 tclarke1
> The 0x4000 bytes of ethernet ram @ 0x7FD00000 can be used for the LCD frame
> buffer (if it is enough). There is no need to enable the ethernet to access
> this ram.
>
> I have not been able to use the 0x4000 bytes of AHB1 ram @ 0x7FE00000 for
> the LCD frame buffer. I can read and write to it from the debugger, but the
> LCD is a no go. It does not seem to matter if the USB is enabled or not. I
> thought I saw a post describing this. Has this been done?
>
>
>
Reply by ●August 29, 20092009-08-29
I had addresses confused.
The USB ram on AHB1 (0x7FD00000) works fine as a LCD frame buffer and there is no need to enable the USB.
The ethernet ram on AHB2 (0x7FE00000) does not work as a LCD frame buffer regardless of if the ethernet is enabled or not.
The UM states in 6.1 that the LCD controller and its DMA can only use external memory or AHB1 memory. The ethernet memory can be used for other things such as general code and data, just not for the LCD.
In my case, the frame buffer is not defined by any data structure. Its just a region of memory pointed to by a register, and accessed via pointers. On real HW, the linker does not really need to know about it. The simulator on the other hand, does need to be told that that region is valid.
--- In l..., Felipe de Andrade Neves Lavratti wrote:
>
> I don't know how to awnser you question, but, did you changed the .ld file
> to match your new RAM config ?
>
> 2009/8/29 tclarke1 >
> >
> > The 0x4000 bytes of ethernet ram @ 0x7FD00000 can be used for the LCD frame
> > buffer (if it is enough). There is no need to enable the ethernet to access
> > this ram.
> >
> > I have not been able to use the 0x4000 bytes of AHB1 ram @ 0x7FE00000 for
> > the LCD frame buffer. I can read and write to it from the debugger, but the
> > LCD is a no go. It does not seem to matter if the USB is enabled or not. I
> > thought I saw a post describing this. Has this been done?
> >
> >
> >
>
>
The USB ram on AHB1 (0x7FD00000) works fine as a LCD frame buffer and there is no need to enable the USB.
The ethernet ram on AHB2 (0x7FE00000) does not work as a LCD frame buffer regardless of if the ethernet is enabled or not.
The UM states in 6.1 that the LCD controller and its DMA can only use external memory or AHB1 memory. The ethernet memory can be used for other things such as general code and data, just not for the LCD.
In my case, the frame buffer is not defined by any data structure. Its just a region of memory pointed to by a register, and accessed via pointers. On real HW, the linker does not really need to know about it. The simulator on the other hand, does need to be told that that region is valid.
--- In l..., Felipe de Andrade Neves Lavratti wrote:
>
> I don't know how to awnser you question, but, did you changed the .ld file
> to match your new RAM config ?
>
> 2009/8/29 tclarke1 >
> >
> > The 0x4000 bytes of ethernet ram @ 0x7FD00000 can be used for the LCD frame
> > buffer (if it is enough). There is no need to enable the ethernet to access
> > this ram.
> >
> > I have not been able to use the 0x4000 bytes of AHB1 ram @ 0x7FE00000 for
> > the LCD frame buffer. I can read and write to it from the debugger, but the
> > LCD is a no go. It does not seem to matter if the USB is enabled or not. I
> > thought I saw a post describing this. Has this been done?
> >
> >
> >
>
>
