LPC43xx running from (external) SDRAM

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Mark

• April 13, 2014 17:59

Hi All,

From what I read in the user manuals and package info, all I need to do to get code downloading to, and running from, SDRAM is change the section placement in the project option to SDRAM.

If I create a new project from any of the LPC43XXX that support external SDRAM, change the section placement to SDRAM, the project fails to build, with an UNPLACED_SECTIONS error.

All the crossworks examples in the LPC4300 and embest LPC4357 fail to link with an overflow of the UNPLACED_SECTIONS, when I change the placement to SDRAM.

The Reset script and section placement files change in the project, so its doing something

What am I missing here?

 

thanks

Mark

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• 

  Bryan Audiffred

  • February 19, 2016 19:43

  I know this is old, but in the interest of posterity...you're missing more than section placement.   You also need to configure pins, clocks, and the EMC peripheral via the debugger.  I use a custom reset script for an SDRAM only build.  

  You probably want to think twice about running from SDRAM on this part.  Bus arbitration is almost non-existent as is cache.  There is a simply priority scheme per the manual.  A while(1) in your idle task will almost entirely consume the bus, blocking other transfers you'd want to occur, like ethernet DMA transfers.

   

  function SDRAMReset(core)
  {
  TargetInterface.pokeWord(0xE000EDF0, 0xA05F0003); // set C_HALT and C_DEBUGEN in DHCSR
  TargetInterface.waitForDebugState(1000);

  // Bit 17 of CREG is reserved. No idea what they are doing here.
  TargetInterface.pokeWord(0x4004312C, TargetInterface.peekWord(0x4004312C)|(1<<17)); // Power up RNG
  // Configure memory map to point to SDRAM
  TargetInterface.pokeWord(0x40043100, 0x28000000); // set M4MEMMAP to SDRAM

  TargetInterface.pokeWord(0xE000EDFC, 0x1); // set VC_CORERESET in DEMCR
  // Chip ERRATA - this will not reset the peripherals as they should
  TargetInterface.pokeWord(0xE000ED0C, 0x05FA0004); // set SYSRESETREQ in AIRCR
  TargetInterface.waitForDebugState(1000);

  SDRAMConfigureEMCPins();
  SDRAMConfigureClocks();
  SDRAMConfigureEMC();
  SDRAMConfigureSPIFIPins();
  }

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