Hi Alexis, I am working on something extremely similar. What are you trying to do with FPGA ?
On Sun, Oct 4, 2015 at 1:56 PM, Alexis Jeandet <[email protected]> wrote: > > Hi, > On Saturday, October 3, 2015 at 1:39:55 PM UTC+2, Jon Smirl wrote: >> >> On Sat, Oct 3, 2015 at 3:53 AM, Rock Slate <[email protected]> wrote: >> > Wow, that's a really detailed response. Thanks a lot for the pointers. >> I >> > will definitely look into this and will let you know as I proceed. >> >> On other processors I have seen people attach SRAM to the LCD >> interface. That technique may be possible on Allwinner but it will >> need some investigation. >> >> I've seen the opposite, I'm interested if you have some links, it would > be a good point to link FPGA to allwinner devices. > >> >> > >> > On Sat, Oct 3, 2015 at 1:16 PM, Siarhei Siamashka >> > <[email protected]> wrote: >> >> >> >> > On Sat, Oct 3, 2015 at 12:32 PM, Rock Slate <[email protected]> >> >> > wrote: >> >> > >> >> > > Hi, >> >> > > >> >> > > Thanks for the reply. Both yes and no. The A13 comes in a nice >> >> > > friendly >> >> > > package which is easy to solder. However the FBGA on the DDR3 is >> >> > > really a >> >> > > nightmare. If not placed correctly, I would have to reball the >> chip >> >> > > and >> >> > > this is a little tough to do since I am not sure if I have the >> right >> >> > > experience for achieving this. >> >> > > >> >> > > However , I have some dedicated code which is really >> small(something >> >> > > like >> >> > > toggling a few pins) to control another interface which I would >> like >> >> > > to do >> >> > > even if the DDR does not work(signal integrity is also a problem , >> >> > > even if >> >> > > ODT is present). >> >> >> >> The DDR3 signal integrity also depends on the DRAM controller >> >> configuration. And this configuration is done by software on >> >> Allwinner A13: http://linux-sunxi.org/DDR_Calibration >> >> >> >> > > I dont want to put in another MCU just for this purpose. >> >> > > >> >> > > I was wondering if its possible to run the A13 without the DDRAM >> being >> >> > > configured. >> >> >> >> I have already answered this particular question. Yes, it is possible. >> >> Your code and data can use a small amount of the on-chip SRAM (48KiB). >> >> Moreover, that's how the bootloaders normally work. The boot ROM does >> >> not normally initialize the DRAM on ARM devices, because there are no >> >> DIMM modules with a nice standardized way to retrieve all the >> necessary >> >> DRAM settings (from SPD). Instead the bootloader code does all this >> >> board-specific configuration job on ARM devices. And bootloaders are >> >> running in SRAM memory, or at least start executing there. >> >> >> >> > > Although I havent read the cortex A8 manual , I am assuming >> >> > > that UBOOT at some level should be able to achieve what I want. >> >> >> >> Just take a look at the SPL part of U-Boot. It gets loaded into the >> >> SRAM, runs from there, takes care of initializing the DRAM and then >> >> loads the main part of U-Boot into the DRAM memory. >> >> >> >> > > It is also an interesting topic since I dont find many papers >> >> > > detailing >> >> > > how to use the ARM without external RAM apart from >> >> > > http://www.coreboot.org/images/6/6c/LBCar.pdf so that I can use >> it as >> >> > > a >> >> > > microcontroller in the initial stages of development. >> >> >> >> Is this paper really about ARM? It looks very much x86 to me. >> >> >> >> Please don't confuse the SRAM memory and CPU L1/L2 caches. You can >> >> already use SRAM easily. It is more than enough for storing your code, >> >> which is responsible for toggling a few pins. Moreover, if your DRAM >> >> happens to be broken, guess how the U-Boot bootloader is able to print >> >> an error message about this mishap on the UART serial console? >> >> >> >> As for the L2 cache, it has a much larger size than SRAM, but it is >> not >> >> normally designed to be used instead of SRAM and DRAM. There might be >> a >> >> way to configure it like this (I did not rule out this possibility >> yet), >> >> but the documentation needs to be checked (ARM Architecture Reference >> >> Manual ARMv7-A and ARMv7-R edition): >> >> >> http://infocenter.arm.com/help/topic/com.arm.doc.ddi0406c/index.html >> >> >> >> -- >> >> Best regards, >> >> Siarhei Siamashka >> > >> > >> > -- >> > You received this message because you are subscribed to the Google >> Groups >> > "linux-sunxi" group. >> > To unsubscribe from this group and stop receiving emails from it, send >> an >> > email to [email protected]. >> > For more options, visit https://groups.google.com/d/optout. >> >> >> >> -- >> Jon Smirl >> [email protected] >> > -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
