Keil Logo

ULINK: Memory Access Error while using ETM Trace on LPC4300

Information in this knowledgebase article applies to:

  • MDK-ARM Version 5.x
  • ULINK Pro Debug Adapter
  • Software Pack: Keil.LPC4300_DFP


I have copied an example from Pack Installer based on LPC4300 and made it compatible for ETM Trace as per the settings but as soon as debug session has been started, I see Cannot access Memory error messages in Command Window:

Cannot access Memory (@ 0x00000050, Read, Acc Size: 4 Byte)
Cannot access Memory (@ 0x00000052, Read, Acc Size: 2 Byte)
Cannot access Memory (@ 0x00000054, Read, Acc Size: 2 Byte)
Cannot access Memory (@ 0x00000056, Read, Acc Size: 2 Byte)
Cannot access Memory (@ 0x00000058, Read, Acc Size: 4 Byte)


The examples provided in Pack Installer are not compatible for ETM Trace and reason of this error is non-synchronization between System Clock and Trace Core Clock. To make these examples compatible for ETM Trace, the System Clock has to be reduced.

In your µVision project open system_LPC43xx.c, scroll down to section Configure PLL1 and change the settings as per below:

/* PLL1 output clock: 120MHz, Fcco: 240MHz, N = 1, M = 20, P = 1              */
#define PLL1_NSEL   0           /* Range [0 -   3]: Pre-divider ratio N       */
#define PLL1_MSEL  19           /* Range [0 - 255]: Feedback-divider ratio M  */
#define PLL1_PSEL   0           /* Range [0 -   3]: Post-divider ratio P      */

#define PLL1_BYPASS 0           /* 0: Use PLL, 1: PLL is bypassed             */
#define PLL1_DIRECT 0           /* 0: Use PSEL, 1: Don't use PSEL             */
#define PLL1_FBSEL  0           /* 0: FCCO is used as PLL feedback            */



Last Reviewed: Tuesday, April 4, 2017

Did this article provide the answer you needed?
Not Sure
  Arm logo
Important information

This site uses cookies to store information on your computer. By continuing to use our site, you consent to our cookies.

Change Settings

Privacy Policy Update

Arm’s Privacy Policy has been updated. By continuing to use our site, you consent to Arm’s Privacy Policy. Please review our Privacy Policy to learn more about our collection, use and transfers
of your data.